Itsabimmerthing

Smoother, Lighter, Faster

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Boat is getting some TLC at the yard and several jobs have already been done.

 

-Hull faired and painted with high build modified epoxy (Durepox)

-All hull thrus converted to flush type from the old mushroom type, Total 7 pcs

-Volvo Rubber fairing replaced with GRP plate, faired into the hull, minimal opening around the saildrive leg

-Keel and Rudder trailing edge converted from 45 degree "offset" to a knife sharp edge

 

Hull was in good shape, not great, never sanded or faired. Can not to see how much the boat has improved.

 

Now, among other things, I am thinking about replacing some of the plywood in inside structure with sandwich composite/Carbon plate or something else that does the job and is light. Has anyone done that? What would be a good source for such plates that can be cut to shape to replace, we say plywood under the fwd. berth mattresses and similar plates that can be easily changed. Part of the idea is to change as much as possible of the plating that is not visible.

 

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Lightening up, Francis:

 

Dunno how your interior is covered, but my ceiling and wall panels were/are (haven't finished the whole boat) thin ply with batting and vinyl stapled to it. I got directed to PVC sheet as a replacement and it's far lighter and is easy to work with (molds with a heat gun). Or sand and paint, or glue in some sort of thin cloth.

 

For what you're doing, I'm using foam sheet and laminating it myself. Prefabbed sheet is quite spendy, not that the foam is cheap either ($200 per 4x8' sheet IIRC). I've replaced access panels, flooring, bunk bottoms, and some structural stuff. In my salon, I replaced plywood/laminate flooring with a mat.

 

Consider textile rigging and lifelines.

 

Thinner foam for mattresses and cushions. Cloth instead of vinyl for covering same.

 

If you really want to go nuts with it, tighten down all bolts and then cut off any excess threads. I laughed when my friend told me about doing that to our ex-F27GS, but then they showed me the bucket of cutoffs and we're talking 50-100lb.

 

Up till recently, I was coastal-cruising. So everything that isn't attached to the boat/necessary lives in tote bags. Keeping stuff in bags makes it easier to take things on/off the boat and to keep an eye on extraneous crap weight.

 

I used to think 'small shit, who cares?' but small shit adds up to big weight cumulatively, it's surprising.

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Durepox is NOT a hi build epoxy UC. A high build would build at DFT's above 300 microns percoat. Durepox will neve do that.

 

The 45 bevel on rudder tailing edge msy have been put there to stop cavitation issues. Be interested if you have any now.

 

Buy a sheet of poly foam (divynicell, Klegicell) and " bag" some carbon cloth on. Then cut to shape.

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The 45 bevel on rudder tailing edge msy have been put there to stop cavitation issues. Be interested if you have any now.

 

I know what you meant, but It is to stop vibration (humming) due to vortice shedding. Cavitation at the trailing edge would result in destruction of the trailing edge. IIRC studies suggest a 30 degree bevel is considered optimal.

 

In a similar vein, with regards to the rudder, many people confuse ventilation with cavitation. Although both relate to pressure, they are completely different phenomena.

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My rudder has a blunt trailing edge nearly an inch wide and I've been thinking about re-profiling it at my next haulout. Do you have a reference on that optimal bevel study?

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I've always understood that the trailing edges of keels & rudders should be slightly squared off, not tapered to a knife edge. Supposedly it promotes cleaner separation.

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The 45 bevel on rudder tailing edge msy have been put there to stop cavitation issues. Be interested if you have any now.

 

I know what you meant, but It is to stop vibration (humming) due to vortice shedding. Cavitation at the trailing edge would result in destruction of the trailing edge. IIRC studies suggest a 30 degree bevel is considered optimal.

 

In a similar vein, with regards to the rudder, many people confuse ventilation with cavitation. Although both relate to pressure, they are completely different phenomena.

Absolutely Correct... caffine intake was required today.... doh!

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I've always understood that the trailing edges of keels & rudders should be slightly squared off, not tapered to a knife edge. Supposedly it promotes cleaner separation.

Interesting stuff Sloopy J. I have played with all three concepts for differing reasons as 12metre outlined above, until a mate,who is a highly regarded hydrodynamics guru said...

 

"Forget all the bullshit and detailed data and testing results i can provide you and just " follow the money"!...

 

... meaning - look at the AC and high end race dudes, who spend the bucks on testing and development, and see what they use!.... they have done all the hard work for you!"

 

He is 100% right.

 

Just look at the rudder design and tailing edges of AC boats ( from 12 m - Cats) over the years!

 

Foil Shapes and tailing edges all relate to boat speed and rudder placement v straght line speed and control/ turning compromises

 

A match racer rudder will be lot different to a one direction/ tack/ reach/ speed machine.

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My rudder has a blunt trailing edge nearly an inch wide and I've been thinking about re-profiling it at my next haulout. Do you have a reference on that optimal bevel study?

With a tailing edge that thick i would forget any studies and just get it down to 3-5 mm.

 

Getting to detailed on a non "top end race boat" is a complete waste of time unless you have controll or rudder vibrtion etc issues.... or you are in a one design fleet and getting pasted everyrace by a dude with a different rudder!

 

Some boats do not benefit greatly from rudder refinement beyound original design. Some boats will never be fast ( for their LOA) and only exceed maximum hull speed when put on a road trailer and moved to another town. Or dropped from a great hieght.

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For me it's not about fast, it's more about performance in light air. Between that fat, blunt trailing edge on the rudder and the lack of any leading or trailing edge fairing on my thruster tunnel, I figure I can get some decent gains with minimal glass work.

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Thruster tunnel needs chaos that work

Like a sort of feathering prop set

They should lie perfectly faired into the hull at rest

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I've always understood that the trailing edges of keels & rudders should be slightly squared off, not tapered to a knife edge. Supposedly it promotes cleaner separation.

 

It was along that line of thinking that lead to Brit Chance developing the fastback stern on Mariner....lol

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My rudder has a blunt trailing edge nearly an inch wide and I've been thinking about re-profiling it at my next haulout. Do you have a reference on that optimal bevel study?

 

IIRC, it was in PYD by Elliasson(sp?) Certainly an inch is too much no matter the section.

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I've always understood that the trailing edges of keels & rudders should be slightly squared off, not tapered to a knife edge. Supposedly it promotes cleaner separation.

 

It was along that line of thinking that lead to Brit Chance developing the fastback stern on Mariner....lol

 

 

Note I said slightly squared off - not big flats and facets. It was test tank scaling problems that caused Mariner.

 

What does Bob have to say about it?

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For the replacing plywood with lighter stuff... I think the only reasonable way is to make them myself. Hard to buy big enough sheets off the shelf. mainly looking to do the bunk bottoms first, 3 cabins. I've been trying to calculate how much weight would come off by doing this...

 

Some say the the trailing edge should be less than 2mm to avoid vibration. Least drag you can get by as sharp as possible trailing edge. Saw a study where "normal" 40 ft productio C/R keel trailing edge of 13-15mm created the same amount of drag as smooth, sanded bottom vs. well rolled on bottom paint.

keel-rudder.gif

PrinciplesOfYachtDesign6.34.jpg

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I've always understood that the trailing edges of keels & rudders should be slightly squared off, not tapered to a knife edge. Supposedly it promotes cleaner separation.

 

It was along that line of thinking that lead to Brit Chance developing the fastback stern on Mariner....lol

 

 

Note I said slightly squared off - not big flats and facets. It was test tank scaling problems that caused Mariner.

 

What does Bob have to say about it?

 

 

Yeah, I was just having some fun - it's just that whenever I see the terms squared off and smooth separation, I have visuals of Mariner's stern. It was an interesting concept nonetheless.

 

One good thing to come about from the Mariner debacle was that by 1977 some syndicates were using 1/3 scale models - but I don't believe there were any tanks large enough to tow models that size at the time, so IIRC they were essentially testing them as live "4mR" yachts.

 

Mariner was based on a 4 ft model, which I believe was the limit of the Stevens tank.

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My rudder has a blunt trailing edge nearly an inch wide and I've been thinking about re-profiling it at my next haulout. Do you have a reference on that optimal bevel study?

IIRC, it was in PYD by Elliasson(sp?) Certainly an inch is too much no matter the section.

Thanks, just downloaded it.

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As to weight of foam versus ply, this should help:

 

http://www.westsystem.com/ss/comparing-cost-and-weight-of-flat-panels/

Thanks.

 

Looking at the weight I should be able to shave off weight equivalent of the (cruising) anchor at its roller, maybe not quite but almost. just by replacing some of the bunk structure with carbon fiber sandwich panels.

 

Now I just need to learn how to laminate things. For making the panel under the mattresses would i need several layers of CF cloth or could it be done just with one?

 

Just finished with the rudder (I got help from a boatshop), sharpish trailing edge and hull/rudder gap filled to minimal clearance :)

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Mattress panels:

 

Unless you just have CF cloth laying around, it's not worth it unless you have a vacuum frame to do this with, in which case you probably wouldn't be asking the question, ;)

 

Your layups depend on the spans involved.

 

I am using 6oz fibreglass cloth over 3/4 in. Divinycell foam with another layer of 6oz cloth on under side. This should be good for span no more than about 2x2 feet. ergo cutouts for bunk access or similar. Not daily walk-on stuff.

 

For larger areas, or heavy traffic, you could laminate two layers of foam with single layer glass over, or you could use 3/4 foam with a couple layers of CF or glass on the bottom and then a single layer of glass/cf on the top.

 

Of course ideally if you have a vacuum setup to lay it with, CF cloth is the lightest option. That said, I'm not doing too badly with my hand-laid-up fibreglass, certainly lighter than the plywood which I am replacing

 

The bigger the area, the less weight you'll save in foam UNLESS you have a vacuum frame to minimise resin use. Never mind the price, ply is far cheaper

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Re: mattress panels:

 

If you're talking about the hatch covers, a good deal of weight can be saved in those alone. I have about 10 of varying area made of 1/2" ply. Total wt is about 50 lbs

 

I've made up a few panels out of Home Depot type 1/2" XPS foam (2 lb/cu ft) and glass cloth. I did some rudimentary "stomp" tests with my 200 lb body and the top compression side failed rather easily with only only 1 lam of 6 oz but was fine with 2 lams. The bottom tension side was fine with just 1 lam of 6 0z. In real life the loading would be less since I was testing in 2 point suspension (or rather 2 edge). As a hatch cover it would be 4 edge, so less loading and stiffer. Carbon absolutely not necessary here . If I had some, I would save it for other applications. Using Divinycell gets pricey, but XPS foam and E-glass, likely cheaper than ply. I wouldn't use XPS for structural pieces, but for things like berth hatch covers, I don't see why not, and about 1/3 the weight of Divinycell.

 

However, with Divinycell, you may only need 1 lam of 6 oz on the top side, rather than 2 (which i think would be required if you used XPS foam instead)

 

I reckon the total weight of all 10 panels will be 10 lbs, so perhaps 40 lbs weight saving there.

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Boat is getting some TLC at the yard and several jobs have already been done.

 

-Hull faired and painted with high build modified epoxy (Durepox)

-All hull thrus converted to flush type from the old mushroom type, Total 7 pcs

-Volvo Rubber fairing replaced with GRP plate, faired into the hull, minimal opening around the saildrive leg

-Keel and Rudder trailing edge converted from 45 degree "offset" to a knife sharp edge

 

Hull was in good shape, not great, never sanded or faired. Can not to see how much the boat has improved.

 

Now, among other things, I am thinking about replacing some of the plywood in inside structure with sandwich composite/Carbon plate or something else that does the job and is light. Has anyone done that? What would be a good source for such plates that can be cut to shape to replace, we say plywood under the fwd. berth mattresses and similar plates that can be easily changed. Part of the idea is to change as much as possible of the plating that is not visible.

 

 

 

let's see, your boat weighs how much? how much weight are you going to save? not worth the effort, time, & money.. if something is rotten, yeah..

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Boat is getting some TLC at the yard and several jobs have already been done.

 

-Hull faired and painted with high build modified epoxy (Durepox)

-All hull thrus converted to flush type from the old mushroom type, Total 7 pcs

-Volvo Rubber fairing replaced with GRP plate, faired into the hull, minimal opening around the saildrive leg

-Keel and Rudder trailing edge converted from 45 degree "offset" to a knife sharp edge

 

Hull was in good shape, not great, never sanded or faired. Can not to see how much the boat has improved.

 

Now, among other things, I am thinking about replacing some of the plywood in inside structure with sandwich composite/Carbon plate or something else that does the job and is light. Has anyone done that? What would be a good source for such plates that can be cut to shape to replace, we say plywood under the fwd. berth mattresses and similar plates that can be easily changed. Part of the idea is to change as much as possible of the plating that is not visible.

 

 

 

let's see, your boat weighs how much? how much weight are you going to save? not worth the effort, time, & money.. if something is rotten, yeah..

 

 

For you this may be true.

 

For others, a lot of little savings can add up to a lot and is worth the effort time and money.

 

Here is a list of small (individually inconsequential) savings I expect to realize from the mods on my 6000 lb boat. That is about a 4% reduction in displacement:

 

ITEM NET

Berth hatches -38

Companionway hatch -12

Cabin Sole -37

Bulkhead -36

Liner -60

Aft Stays and blocks -15

Runner winches -20

Blocks - 2

Chainplates -10

TOTAL: -230

 

My numbers may be a bit generous, but not too far off I think - maybe 200 lbs.

 

Mind you, I'm also building more of a cruising interior, so there will likely be an overall gain in the end, but it will be 200 lbs less than it would have been.

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Boat is getting some TLC at the yard and several jobs have already been done.

 

-Hull faired and painted with high build modified epoxy (Durepox)

-All hull thrus converted to flush type from the old mushroom type, Total 7 pcs

-Volvo Rubber fairing replaced with GRP plate, faired into the hull, minimal opening around the saildrive leg

-Keel and Rudder trailing edge converted from 45 degree "offset" to a knife sharp edge

 

Hull was in good shape, not great, never sanded or faired. Can not to see how much the boat has improved.

 

Now, among other things, I am thinking about replacing some of the plywood in inside structure with sandwich composite/Carbon plate or something else that does the job and is light. Has anyone done that? What would be a good source for such plates that can be cut to shape to replace, we say plywood under the fwd. berth mattresses and similar plates that can be easily changed. Part of the idea is to change as much as possible of the plating that is not visible.

 

 

 

let's see, your boat weighs how much? how much weight are you going to save? not worth the effort, time, & money.. if something is rotten, yeah..

 

Sorry dreaded, not my mentality. I like working on my boat, that's big part of the hobby.

 

And any weight of the bow/stern will help, a lot. Yes, my boat is C/R so the displacement is somewhat high, even it is pretty light boat, but weight on the bow/stern is just wrong on any boat.

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Boat is getting some TLC at the yard and several jobs have already been done.

 

-Hull faired and painted with high build modified epoxy (Durepox)

-All hull thrus converted to flush type from the old mushroom type, Total 7 pcs

-Volvo Rubber fairing replaced with GRP plate, faired into the hull, minimal opening around the saildrive leg

-Keel and Rudder trailing edge converted from 45 degree "offset" to a knife sharp edge

 

Hull was in good shape, not great, never sanded or faired. Can not to see how much the boat has improved.

 

Now, among other things, I am thinking about replacing some of the plywood in inside structure with sandwich composite/Carbon plate or something else that does the job and is light. Has anyone done that? What would be a good source for such plates that can be cut to shape to replace, we say plywood under the fwd. berth mattresses and similar plates that can be easily changed. Part of the idea is to change as much as possible of the plating that is not visible.

 

 

 

let's see, your boat weighs how much? how much weight are you going to save? not worth the effort, time, & money.. if something is rotten, yeah..

 

Sorry dreaded, not my mentality. I like working on my boat, that's big part of the hobby.

 

And any weight of the bow/stern will help, a lot. Yes, my boat is C/R so the displacement is somewhat high, even it is pretty light boat, but weight on the bow/stern is just wrong on any boat.

 

 

so 200lbs on an 8000lb boat, that's like 2.5%.. have you considered you and your crew going on a diet, you might save additional weight there.. hell I could lose 40lbs, that'd be 1.5% on my boat..

 

 

you're better off concentrating on sail trim, sailing technique, winning starts, tactics, strategy, reducing weather helm, & cleaning the bottom to win races.. or buy a faster boat

 

yeah, if something needs to be fixed, fix it , but to do all this work for little gain, I'd rather get on the water and practice, that's where you'll make the most gains.. one bad tack and all that work becomes useless

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Boat is getting some TLC at the yard and several jobs have already been done.

 

-Hull faired and painted with high build modified epoxy (Durepox)

-All hull thrus converted to flush type from the old mushroom type, Total 7 pcs

-Volvo Rubber fairing replaced with GRP plate, faired into the hull, minimal opening around the saildrive leg

-Keel and Rudder trailing edge converted from 45 degree "offset" to a knife sharp edge

 

Hull was in good shape, not great, never sanded or faired. Can not to see how much the boat has improved.

 

Now, among other things, I am thinking about replacing some of the plywood in inside structure with sandwich composite/Carbon plate or something else that does the job and is light. Has anyone done that? What would be a good source for such plates that can be cut to shape to replace, we say plywood under the fwd. berth mattresses and similar plates that can be easily changed. Part of the idea is to change as much as possible of the plating that is not visible.

 

 

 

let's see, your boat weighs how much? how much weight are you going to save? not worth the effort, time, & money.. if something is rotten, yeah..

 

Sorry dreaded, not my mentality. I like working on my boat, that's big part of the hobby.

 

And any weight of the bow/stern will help, a lot. Yes, my boat is C/R so the displacement is somewhat high, even it is pretty light boat, but weight on the bow/stern is just wrong on any boat.

 

 

so 200lbs on an 8000lb boat, that's like 2.5%.. have you considered you and your crew going on a diet, you might save additional weight there.. hell I could lose 40lbs, that'd be 1.5% on my boat..

 

 

you're better off concentrating on sail trim, sailing technique, winning starts, tactics, strategy, reducing weather helm, & cleaning the bottom to win races.. or buy a faster boat

 

yeah, if something needs to be fixed, fix it , but to do all this work for little gain, I'd rather get on the water and practice, that's where you'll make the most gains.. one bad tack and all that work becomes useless

 

 

While you are correct - you don't seem to get it. There are people like Bimmer and myself that actually like doing these sort of projects. It is almost like an addiction. Whether it actually makes the boat any faster is pretty much irrelevant.

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I've always understood that the trailing edges of keels & rudders should be slightly squared off, not tapered to a knife edge. Supposedly it promotes cleaner separation.

Laminar flow

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Saving weight is always benificial in a yacht as every Kg saved is a kg less pressure required on your sail area to provide the same downwind speed.

 

The figure is less upwind

 

But...

 

Say you took a 30 footer full out race yacht that sailed on it designed waterline @ say 1500 kg displacement and some how reduced its eight to 100 kg it would be slow upwind because can it would sail on a reduced WL. But of course we would take that lost weight and put it into the keel and get a upwind stiffness benefit.... but be slower downwind.

 

So ...Any weight in the wrong place is SLOW!!!

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Boat is getting some TLC at the yard and several jobs have already been done.

 

-Hull faired and painted with high build modified epoxy (Durepox)

-All hull thrus converted to flush type from the old mushroom type, Total 7 pcs

-Volvo Rubber fairing replaced with GRP plate, faired into the hull, minimal opening around the saildrive leg

-Keel and Rudder trailing edge converted from 45 degree "offset" to a knife sharp edge

 

Hull was in good shape, not great, never sanded or faired. Can not to see how much the boat has improved.

 

Now, among other things, I am thinking about replacing some of the plywood in inside structure with sandwich composite/Carbon plate or something else that does the job and is light. Has anyone done that? What would be a good source for such plates that can be cut to shape to replace, we say plywood under the fwd. berth mattresses and similar plates that can be easily changed. Part of the idea is to change as much as possible of the plating that is not visible.

 

 

 

let's see, your boat weighs how much? how much weight are you going to save? not worth the effort, time, & money.. if something is rotten, yeah..

 

 

For you this may be true.

 

For others, a lot of little savings can add up to a lot and is worth the effort time and money.

 

Here is a list of small (individually inconsequential) savings I expect to realize from the mods on my 6000 lb boat. That is about a 4% reduction in displacement:

 

ITEM NET

Berth hatches -38

Companionway hatch -12

Cabin Sole -37

Bulkhead -36

Liner -60

Aft Stays and blocks -15

Runner winches -20

Blocks - 2

Chainplates -10

TOTAL: -230

 

My numbers may be a bit generous, but not too far off I think - maybe 200 lbs.

 

Mind you, I'm also building more of a cruising interior, so there will likely be an overall gain in the end, but it will be 200 lbs less than it would have been.

 

Oh dear. Better delete this post. The raters will think you are definitely as fast as AK. :)

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So ...Any weight in the wrong place is SLOW!!!

 

 

true , but it's not as slow as one bad tack or dragging the rudder through the water..

Well? Maybe it is...

 

There are contollables and uncontrollables. Weight is something you drag around with you every race, tack, hour, or minute!... it is somethng you can eliminate physically ...and mentally. Cumulatively it is worse over a seasonthan a few bad tacks

 

Bad tacks you can improve on and everybody has one. and unfortunately you need a rudder, so make it the fastest shape

 

I always want my boat light and then its just time on the water tuning speed and angles and getting crew work correct.

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Boat is getting some TLC at the yard and several jobs have already been done.

 

-Hull faired and painted with high build modified epoxy (Durepox)

-All hull thrus converted to flush type from the old mushroom type, Total 7 pcs

-Volvo Rubber fairing replaced with GRP plate, faired into the hull, minimal opening around the saildrive leg

-Keel and Rudder trailing edge converted from 45 degree "offset" to a knife sharp edge

 

Hull was in good shape, not great, never sanded or faired. Can not to see how much the boat has improved.

 

Now, among other things, I am thinking about replacing some of the plywood in inside structure with sandwich composite/Carbon plate or something else that does the job and is light. Has anyone done that? What would be a good source for such plates that can be cut to shape to replace, we say plywood under the fwd. berth mattresses and similar plates that can be easily changed. Part of the idea is to change as much as possible of the plating that is not visible.

 

 

 

let's see, your boat weighs how much? how much weight are you going to save? not worth the effort, time, & money.. if something is rotten, yeah..

 

 

For you this may be true.

 

For others, a lot of little savings can add up to a lot and is worth the effort time and money.

 

Here is a list of small (individually inconsequential) savings I expect to realize from the mods on my 6000 lb boat. That is about a 4% reduction in displacement:

 

ITEM NET

Berth hatches -38

Companionway hatch -12

Cabin Sole -37

Bulkhead -36

Liner -60

Aft Stays and blocks -15

Runner winches -20

Blocks - 2

Chainplates -10

TOTAL: -230

 

My numbers may be a bit generous, but not too far off I think - maybe 200 lbs.

 

Mind you, I'm also building more of a cruising interior, so there will likely be an overall gain in the end, but it will be 200 lbs less than it would have been.

 

Oh dear. Better delete this post. The raters will think you are definitely as fast as AK. :)

 

 

Even if it were, I doubt I could sail at the same level as AK

 

I'm not overly concerned about what PHRF does. If I bother to race, it will most likely be single or short handed. i'm really tired of dealing with crew issues these days. I just want to putt around the bay or along the coast - as fast as i can.

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I believe all these small jobs (all not so small) add up and will result in better performance, plus they are fun projects for off-season . I list them again for reference, with estimated reduction in drag, drags numbers are gathered from articles around the internet so have no idea of their accuracy.

 

-Good quality hull, not faired -> Faired and longboarded carefully (-30N)

-Rolled on AF -> Glossy smooth epoxy bottom (-40N)

-7 mushroom hull thrus -> Flush hull thrus (-4N)

-Saildrive rubber removed -> GRP plate made and sunk/faired around the leg, minimal clearance (-2N)

-Keel/Rudder trailing edges from 12mm (before the bevel) -> Profile extended to achieve as sharp trailing edge as possible. (-30+25N)

-Rudder-Hull Gap closed completely, minimal clearance (-3N)

 

Total: 134N less drag, Not a specialist in this stuff but I am hoping for noticeable difference in light airs/pointing.

 

Next project is removing weigh from the bow/stern to minimize pitching. Thanks all for the advice on that. Also making some storage for all the heavy item near the top of the keel. Thinking about weight minimizing above the Center of Gravity and moving as much of it close to the top of the keel.

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Maybe I missed it but regarding your rudder trailing edge, did you notice any change in rudder effort when you extended it?

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Boat has not been in the water yet... So all the jobs, and their possible effects, will come at once. The area is very little changed, so I doubt there will be much change...

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Has anyone done that? What would be a good source for such plates that can be cut to shape to replace..

 

 

www.fibrefusion.com in Falmouth UK do composite flat panels. They'll also water jet cut them to accurate shapes if you have the cad files/whatever. Haven't used them myself, but I know people who have.

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It's always a trade-off in picking ways to lighten a boat.

I've found it useful to decide, at the outset, what was the value of a pound eliminated.

Ask yourself how much the value of the boat would be increased/decreased by losing/gaining a pound or a thousand pounds. Then apply that threshhold to alternative methods/materials.

For my own boat, I figured that $50/lb. was in the ballpark (YMMV), so composite cored panels were worth doing.

Vacuum bagging panels on a table is dead easy.

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I think atleast in the "extremes" all weight should be minimized and will be of benefit, such as forward island-bed structure, quite easy to remove several kg's/Lbs there.

 

Now my Batteries are on both sides of the engine, will take alook if I could move them forward closer to the keel, maybe under the U-sofa. (might not be a good/necessary idea as that space is now dedicated for anchor, tools, extra water, etc...

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moving batteries... some thoughts

 

consider the possibility of off-gassing and the area to which you contemplate moving them

Thicker and longer cabling?

Batts are cooler being away from hot engine room, so helps longevity

carbon-foam? LFP?

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Re flat panels:

Set up a table using melamine/formica faced mdf, saw horses and 4" x 1" straight edges (wood, alloy or steel) and you will not have to fair the panels. If it is bigger than one sheet, glue and seal the joins. Buy a $150 vac pump from ebay and bag or infuse the panels and you will save about 50% of the resin in the job and ensure a much better bond and finish. And you won't get sticky.

Cut your foam to shape before you glass it as it is easier to trim raw foam to get the shape rather than glass/foam.

Cut a rebate around the edge on the non table side of your panels and fold the glass around the edge and you will have no trimming at all and a better bond to the hull and/or no edge finishing..

Use peel ply against the mould and you won't need to sand the panels pre paint. Use thin plastic (not mylar) against the mould and you won't need to polish it.

 

If you infuse, you can laminate both sides at once, plus any cut outs, rebates, solids, hatches, doors, etc all in one step. Plus, it is the coolest boat building operation you will ever see or do.

 

see http://harryproa.com/?page_id=1327 for more info on infusing

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Re flat panels:

Set up a table using melamine/formica faced mdf, saw horses and 4" x 1" straight edges (wood, alloy or steel) and you will not have to fair the panels. If it is bigger than one sheet, glue and seal the joins. Buy a $150 vac pump from ebay and bag or infuse the panels and you will save about 50% of the resin in the job and ensure a much better bond and finish. And you won't get sticky.

Cut your foam to shape before you glass it as it is easier to trim raw foam to get the shape rather than glass/foam.

Cut a rebate around the edge on the non table side of your panels and fold the glass around the edge and you will have no trimming at all and a better bond to the hull and/or no edge finishing..

Use peel ply against the mould and you won't need to sand the panels pre paint. Use thin plastic (not mylar) against the mould and you won't need to polish it.

 

If you infuse, you can laminate both sides at once, plus any cut outs, rebates, solids, hatches, doors, etc all in one step. Plus, it is the coolest boat building operation you will ever see or do.

 

see http://harryproa.com/?page_id=1327 for more info on infusing

Except in a autoclave.

 

Mind you NONA ( no Autoclave No Oven) or OA OO ( Out of Autoclave. Out of Oven) methods are producing amazing componants and panels faster and with equal weight/ strength. The French are bigtime into it.

 

Unduction heating of the Fibre, and double mold presses make vacum bagging look average... but while its cheaper than Autoclaves etc its still expensive.

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moving batteries... some thoughts

 

consider the possibility of off-gassing and the area to which you contemplate moving them

Thicker and longer cabling?

Batts are cooler being away from hot engine room, so helps longevity

carbon-foam? LFP?

Batteries are in both aft cabins under the bunks, so not really a problem with heat... Checked the distance that the batteries could be brought forward, around 2m/10ft. And the current battery space would need to be used for other heavy items, so not really a possibility.

 

However, will need to look at switching to Lithium or possibly Lithium + a fuel cell. I guess with lithium you can come down quite a lot on the capacity on the AGM's? Say from 300Ah to 200Ah or something like that. (Will need to read that other thread going on on the case) With added Fuelcell, EFOY for example, you could for sure come down on the capacity. There would be some seriuos weight savings, with price though...

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Re flat panels:

Set up a table using melamine/formica faced mdf, saw horses and 4" x 1" straight edges (wood, alloy or steel) and you will not have to fair the panels. If it is bigger than one sheet, glue and seal the joins. Buy a $150 vac pump from ebay and bag or infuse the panels and you will save about 50% of the resin in the job and ensure a much better bond and finish. And you won't get sticky.

Cut your foam to shape before you glass it as it is easier to trim raw foam to get the shape rather than glass/foam.

Cut a rebate around the edge on the non table side of your panels and fold the glass around the edge and you will have no trimming at all and a better bond to the hull and/or no edge finishing..

Use peel ply against the mould and you won't need to sand the panels pre paint. Use thin plastic (not mylar) against the mould and you won't need to polish it.

 

If you infuse, you can laminate both sides at once, plus any cut outs, rebates, solids, hatches, doors, etc all in one step. Plus, it is the coolest boat building operation you will ever see or do.

 

see http://harryproa.com/?page_id=1327 for more info on infusing

Except in a autoclave.

 

Mind you NONA ( no Autoclave No Oven) or OA OO ( Out of Autoclave. Out of Oven) methods are producing amazing componants and panels faster and with equal weight/ strength. The French are bigtime into it.

 

Unduction heating of the Fibre, and double mold presses make vacum bagging look average... but while its cheaper than Autoclaves etc its still expensive.

 

An autoclave will give slightly better weight than infusion, but is no where near as cool, particularly for anyone who has ever hand laminated.

 

Double mould presses are great for flat panels (once you have learnt the lessons regarding outgassing and air entrapment), or if the production run is big enough to justify matching moulds. But for one off panels with rebates, cutouts or different thickness laminates or core, they are not the answer. For what the OP wants, Intelligent Infusion will be a lot of fun.

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Has anyone done or knows about a C/R that has been "upgraded" from standard to as good as possible bottom, weight reduction where possible etc..? What sort of gains have you noticed? Speed/pointing etc...

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Faster Boats = LIGHTER, STIFFER, FAIRER, AERO/HYDRO DYNAMIC = MONEY + TIME.

 

Faster crews = compatible, committed, focussed, + TIME + MONEY.

 

THAT COVERS IT.

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A friend of mine was doing an extensive rebuild on an open 40. Owner decided he absolutely HAD to have a CF prop shaft strut. It wasn't included in the original estimate, so it was a time and materials add-on. Now understand, the motor was amidships. Shaft, strut, and prop were several feet behind keel...nowhere near the end of the boat, and below the hull. An unmeasurable speed difference. The CF strut, fabricated and installed, was $4000. Some people got more money and ego than brains.

Jesus...it's like the assclown who bought titanium external tangs for the mast of his 50 year-old Morgan 34 several years ago, and then filed suit. There's several things that could wake up the performance of a vintage CCA boat, but titanium tangs are so far down the list it's pure foolishness to even consider.

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Has anyone done or knows about a C/R that has been "upgraded" from standard to as good as possible bottom, weight reduction where possible etc..? What sort of gains have you noticed? Speed/pointing etc...

You can spend $100K and go a couple tenths faster. Your money...thanks for supporting the marine industry.

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Has anyone done or knows about a C/R that has been "upgraded" from standard to as good as possible bottom, weight reduction where possible etc..? What sort of gains have you noticed? Speed/pointing etc...

 

I don't have any examples, but it is easy enough to test for the weight. Put a couple of weighed bodies on board and motor at a given speed and/or revs on a calm day. Also check how long it takes to accelerate from a set speed to a higher one. Then remove the bodies and repeat the tests. Won't give you any exact numbers, but will give you a feel for the performance gains. If you enjoy messing about with boats, the work and cost will certainly be worth it from a satisfaction and enjoyment pov.

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On my boat, a 45' C/R about 10.000 Kgs, the possibilities to reduce weight are limited but it is possible to place it more prudently ie. minimize pitching and also get the desired trim by crew position on the rail (We race with crew of 10). At least that's the way I see it.

 

For the bottom job I am excpecting most gains from the hull fairing and durepox bottom.

Second most effective improvement i believe to be the modification of keel/rudder trailing edges from chamfer to "knife" edge and filling the hull/ruddr gap.

Third most effect should come from making everything under the hull flush: Hull thrus, Saildrive rubber replaced with a grp plate.

 

In addition we are upgrading the rudder bearings and re organizing some control lines. Have 170cm dia S/S wheel now, thinking about changing that to carbon.

 

Sails are all new, 3DL860, Next one up for a change is Medium/Heavy jib, Code Zero and S2 & S4 are still ok but at some point those will need to go for permanent vacation.

 

Boat sailed well as it was, now I hope to see improvements in light to medium airs and acceleration out of tacks.

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Weight on the mast is 7 more important than weight in the hull therefore try removing all the unnecessary shit from the mast. Strip halyards, change all the rigging to synthetic.

 

Then mast is as light as you can afford ho through the deck. Remove all unnecessary winches, fittings etc.

 

Carbon wheel is a waste of money, but carbon rudder could give you exceptional results.

 

Inside the boat, some weight might be saved by making composite floorboards. Also look into your headliner if it is made from plywood panels or other heavy stuff go for foam covered with vinyl or similar lightweight solution. Remove all the doors that are hinged, remove salon table. Afterwards go sailing and look which items are necessary for you and which you can live without. You will be surprised to see how many shit is not required.

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Mast is about about as light as it can be without buying a carbon stick. Backstay is fiber, rest of the standing rigging is dyform. When time comes to change them I will look at the options.

 

Removing doors/tabletops is not really an option as my aim is to have "Wolf in sheeps clothing" - everything looks standard but isn't.

 

Need to figure out a way to start making or find someone who can make custom panels (and structures) for reasonable price. I would like learn to do it myself as it would be a nice off-season job to replace parts here and there... Biggest problem is that I do not have a space for laminating works..

 

Carbon wheel would be partly for looks, my current S/S wheel is damaged so I use that as an excuse to get a new one :), might opt for a cheaper composite wheel instead of carbon, still less than half the weight of S/S.

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Power developed from sails has to push weight and friction.

 

Refining every componant that adds friction ( in Air and water) is as important as weight. Some say mor important.

 

It never fails to astound me when dudes spend hours of faring their rig, hull, rudder, and Keel then put crew on board in clothes that have the aerodynamics of a brick!

 

Then they have a cabin from the same designer of the said brick. Yet the cabin is a big area that travels thru the air at the same speed as the sails you have spent thousands on to get perfect!

 

THey then sail with a hull shape from the design board of benny hill. Yet simple refinement can produce gains.

 

The funniest thing is the dude that spends hours to sand smooth the botton with 1000 grit in random directions when a 400 sand in the direction of the water flow is faster..... then... they sail with the "unsmooth" topsides in water all day.

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Some pictures of the work in progress...

 

Sailed last season without the Saildrive rubber fairing, now it is glassed flush as in the picture (Pic from saildrive is after 3 months idle in the med, therefore the growth...)

 

Rudder and keel will hopefully add some performance.

 

Hullthrus from mushroom to flush, total 7 of them.

 

Paint job in general was ok Cruising standard now we go for a fair and smooth Durepox+Clear bottom

 

Hopefully these add up...

post-112133-0-06778800-1473317488_thumb.jpg

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post-112133-0-23810800-1473317688_thumb.jpg

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post-112133-0-77786500-1473317775_thumb.jpg

post-112133-0-07229900-1473322715_thumb.jpg

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Seven hull thrus?...

 

If it was me i would have rationalised down to one with clever plumbing and valves.... and that one could have gone via the transom.

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Yeah, that's the ticket. Bubski is on out again. The weight savings from combining the shit outlet with the engine intake and putting them both above the waterline is a little known technique.

 

You should thank him profusely. No one else here was going to give that one up for free ...

 

If you're really lucky, he'll explain how to save weight aloft by removing one cap shroud and tacking the other.

 

Shhhh ...

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Yeah, that's the ticket. Bubski is on out again. The weight savings from combining the shit outlet with the engine intake and putting them both above the waterline is a little known technique.

You should thank him profusely. No one else here was going to give that one up for free ...

If you're really lucky, he'll explain how to save weight aloft by removing one cap shroud and tacking the other.

Shhhh ...

ha ha. Im talking outlets to outlets and friction savings from all those hull skin fittings sucking water all day.

 

I have seen above water inlets with carbon drop down pipes!... so it can be done with one and tgphe weight of running these depends on how you do it. You can have a race mode with most tubes removed, which is lighter than existing setups..

 

Just gotta think inside the square.

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Have you used the boat since you faired the SD opening solid like that?

I have saildrives, and I used a rubber boot for fairing. Partially because there's enough movement in the SD that it needs something flexible up against the leg.

 

Don't be surprised if the fairing either develops cracks or it rubs on the drive, or both. And where your fairing chafes on the drive, it'll eat whatever coating you have on the SD leg, which then means you'll be open for galvanic action, never mind fouling.

 

My SD fairing is rubber of some flavor. it was a conveyor belt at one time. I went to the local plastics shop and asked "what's going to stick to my hull, will be fine underwater, and won't mind paint on it?"

 

Boot glued to the hull with the plastics shop's suggested adhesive. I then faired along the boot's outboard edges which: they're... fair, and the fairing also keeps the edge from peeling up, helps the seal. Been since 2013, so it works.

 

YMMV...

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We looked at option of combining some of the outlets and also Flowtech valves before we started with the hull thrus..

 

Combining was not practical and there was not enough clearance for Flowtech Valves.

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Haven

 

Have you used the boat since you faired the SD opening solid like that?

I have saildrives, and I used a rubber boot for fairing. Partially because there's enough movement in the SD that it needs something flexible up against the leg.

 

Don't be surprised if the fairing either develops cracks or it rubs on the drive, or both. And where your fairing chafes on the drive, it'll eat whatever coating you have on the SD leg, which then means you'll be open for galvanic action, never mind fouling.

 

My SD fairing is rubber of some flavor. it was a conveyor belt at one time. I went to the local plastics shop and asked "what's going to stick to my hull, will be fine underwater, and won't mind paint on it?"

 

Boot glued to the hull with the plastics shop's suggested adhesive. I then faired along the boot's outboard edges which: they're... fair, and the fairing also keeps the edge from peeling up, helps the seal. Been since 2013, so it works.

 

YMMV...

Haven't used the boat with the new SD fairing yet. Clearance should be fine, tested on other boats with S-120/S-130. X-yachts etc... We will see.

 

Without the rubber it was for sure not good for light airs, rubber slightly better, this plate should be as good as possible drag wise?

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Durepox is NOT a hi build epoxy UC. A high build would build at DFT's above 300 microns percoat. Durepox will neve do that.

 

The 45 bevel on rudder tailing edge msy have been put there to stop cavitation issues. Be interested if you have any now.

 

Buy a sheet of poly foam (divynicell, Klegicell) and " bag" some carbon cloth on. Then cut to shape.

I think that's called the Van Lammerer effect. A trailing edge will actually generate less vortex turbulence if it is beveled as opposed to knife edged although how thick is OK was not found in a search of my intracranial database. :wacko:

 

Have had good luck with cheapo lightweight bunk panels made from two sheets of exterior grade, 1/8" plywood doorskin sandwiched around 3/8" R 9 closed cell foam insulation sheets, all from Home Depot. Peel the foil off the foam, roll West epoxy onto the mating surfaces of the ply and weight the whole thing down with 3/4" sheet of ply topped with some cinder bocks and my daugther's blow up wading pool filled with water. Wait for it to cure and presto, cut to fit and done! Got the idea watching Dennis Choate build teak faced furniture panels for one of his boats.

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Durepox is NOT a hi build epoxy UC. A high build would build at DFT's above 300 microns percoat. Durepox will neve do that.

The 45 bevel on rudder tailing edge msy have been put there to stop cavitation issues. Be interested if you have any now.

Buy a sheet of poly foam (divynicell, Klegicell) and " bag" some carbon cloth on. Then cut to shape.

 

I think that's called the Van Lammerer effect. A trailing edge will actually generate less vortex turbulence if it is beveled as opposed to knife edged although how thick is OK was not found in a search of my intracranial database. :wacko:

 

Have had good luck with cheapo lightweight bunk panels made from two sheets of exterior grade, 1/8" plywood doorskin sandwiched around 3/8" R 9 closed cell foam insulation sheets, all from Home Depot. Peel the foil off the foam, roll West epoxy onto the mating surfaces of the ply and weight the whole thing down with 3/4" sheet of ply topped with some cinder bocks and my daugther's blow up wading pool filled with water. Wait for it to cure and presto, cut to fit and done! Got the idea watching Dennis Choate build teak faced furniture panels for one of his boats.

Yip!... kinardly argue with that.

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Durepox is NOT a hi build epoxy UC. A high build would build at DFT's above 300 microns percoat. Durepox will neve do that.

 

The 45 bevel on rudder tailing edge msy have been put there to stop cavitation issues. Be interested if you have any now.

 

Buy a sheet of poly foam (divynicell, Klegicell) and " bag" some carbon cloth on. Then cut to shape.

I think that's called the Van Lammerer effect. A trailing edge will actually generate less vortex turbulence if it is beveled as opposed to knife edged although how thick is OK was not found in a search of my intracranial database. :wacko:

 

Have had good luck with cheapo lightweight bunk panels made from two sheets of exterior grade, 1/8" plywood doorskin sandwiched around 3/8" R 9 closed cell foam insulation sheets, all from Home Depot. Peel the foil off the foam, roll West epoxy onto the mating surfaces of the ply and weight the whole thing down with 3/4" sheet of ply topped with some cinder bocks and my daugther's blow up wading pool filled with water. Wait for it to cure and presto, cut to fit and done! Got the idea watching Dennis Choate build teak faced furniture panels for one of his boats.

 

 

I've thought about doing that for panels & partitions. How much weight saving is there compared to solid ply?

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Couldn't say but I figured I got the equivalent of 3/8" ply for rigidity for the weight of not much more than 1/4" ply. Hey, other foams I'm sure are better but I was boat broke and wanted to try something. Also have to say birch faced ply is pretty with a coat of varnish.

 

Dennis was showing me the interior options for one of his 40s and I asked him about weight savings. He responded by dragging me down into the saloon where one of his guys was building an interior. He grabbed a built up foam/teak doorskin panel that was maybe two feet by four feet and waving it around like an envelope. "See, it doesn't weigh anything".

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I've thought about it and if I was going to make it into actual furniture, I would plan the panels, draw the outlines including drawer enclosures, door edges and so on and place 1/2" timber along those edges so that when I cut the final panel there would be a good strong edge for wear resistance or edge glueing or rabbeting or whatever. I do't think I'd rely on the core material to hold up at those loations. Does that make sense?

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Was inside my 1983 J/29 and almost every corner of the under bunk areas (straight 3/8" plywood) has a little rot in every outboard corner, which in turn has rotted out the bottom of the vernier on the aft of the bulkhead

The vertical walls holding the berth upright had 5/16 plywood with a vernier over it and was rotten in the lower corners, looks like the vernier sucked the water that might have on the floor and left it in the ply?? The Vernier was the only thing holding the ply in place

it's all out!

 

http://www.fiberlay.com/prod-core-materials.php?cat=Thermoplastic%20Core&subclass=406025-4066150&startrow=0

 

now just where to find 1/8" door skins (ala Dennis Choate) that aren't already on a door. There's a cabinet shop next door to my wife's business..hopefully,

then give a shot at some vacuum bagging the panels together with a glass wrap around the edges and over the facing vernier...water will never get into there again!

Anybody know how to make any resin I put over the exterior facing to be dull, rather than shinny?

Shinny is OK but it would just get scuffed from feet or sail bags hitting it.

I'll take look at my West Systems book...could always give it a light sanding with maybe 400?

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You can get 1/8" ply at plywood specialty shops - Windsor Ply is good and pretty widespread I think. They sell nice 1/8" teak faced ply pretty cheap - $50 or $60 a sheet IIRC.

 

To kill gloss on resin I'd use bronze wool if working on the boat - steel wool if you're doing it at home. 400 grit will give you a very dull "sanded" looking surface whereas the wool will just cut the gloss.

 

I'd actually put some "rubbed effect" or semi gloss varnish down rather than leaving the resin as the topcoat and then rubbing it down - a lot less work for a similar result.

 

I don't see the need to wrap glass over the edges - just brush on a good coat of epoxy and they'll be sealed up. Less work, less expense and a better finish on the edges compared to trying to wrap fabric over a sharp corner.

 

For making up flat panels, if you aren't already equipped for bagging, just putting a sheet of 3/4" MDF on top of the glued up panel and then stacking some cinder blocks or similar weights on top of that will give you all the clamping pressure you need.

 

Note: all these comments are in regard to berth flats, partitions and so forth, not structural bulkheads.

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You can get 1/8" ply at plywood specialty shops - Windsor Ply is good and pretty widespread I think. They sell nice 1/8" teak faced ply pretty cheap - $50 or $60 a sheet IIRC.

 

To kill gloss on resin I'd use bronze wool if working on the boat - steel wool if you're doing it at home. 400 grit will give you a very dull "sanded" looking surface whereas the wool will just cut the gloss.

 

I'd actually put some "rubbed effect" or semi gloss varnish down rather than leaving the resin as the topcoat and then rubbing it down - a lot less work for a similar result.

 

I don't see the need to wrap glass over the edges - just brush on a good coat of epoxy and they'll be sealed up. Less work, less expense and a better finish on the edges compared to trying to wrap fabric over a sharp corner.

 

For making up flat panels, if you aren't already equipped for bagging, just putting a sheet of 3/4" MDF on top of the glued up panel and then stacking some cinder blocks or similar weights on top of that will give you all the clamping pressure you need.

 

Note: all these comments are in regard to berth flats, partitions and so forth, not structural bulkheads.

Got it, nothing structural in my project...YET!

Thanks for the advice on dull finishes, I'll try some both ways.

I'm going to give vacuum bagging a try, have a few other projects down the line.

Want a wood look with the wood totally enclosed in glass/resin so I'll wrap it around

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You can get 1/8" ply at plywood specialty shops - Windsor Ply is good and pretty widespread I think. They sell nice 1/8" teak faced ply pretty cheap - $50 or $60 a sheet IIRC.

 

To kill gloss on resin I'd use bronze wool if working on the boat - steel wool if you're doing it at home. 400 grit will give you a very dull "sanded" looking surface whereas the wool will just cut the gloss.

 

I'd actually put some "rubbed effect" or semi gloss varnish down rather than leaving the resin as the topcoat and then rubbing it down - a lot less work for a similar result.

 

I don't see the need to wrap glass over the edges - just brush on a good coat of epoxy and they'll be sealed up. Less work, less expense and a better finish on the edges compared to trying to wrap fabric over a sharp corner.

 

For making up flat panels, if you aren't already equipped for bagging, just putting a sheet of 3/4" MDF on top of the glued up panel and then stacking some cinder blocks or similar weights on top of that will give you all the clamping pressure you need.

 

Note: all these comments are in regard to berth flats, partitions and so forth, not structural bulkheads.

Got it, nothing structural in my project...YET!

Thanks for the advice on dull finishes, I'll try some both ways.

I'm going to give vacuum bagging a try, have a few other projects down the line.

Want a wood look with the wood totally enclosed in glass/resin so I'll wrap it around

 

 

If you are bagging sheets of ply onto foam or balsa, make sure there is a route for the air to escape. Either gaps in the core or holes in the skin, with a bleeder cloth on top.

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If the plywood bunk tops and other structural components are in good condition (no rot or delamination, etc), you can cut them away 2-3 inches from the glassed-in edges, and then use your foam core panels to fill in the removed area. This will avoid a lot of sanding, grinding and laminating, while achieving your weight-removing goal and preserving the present structural integrity of your boat.

 

I would first remove weight from the bow of the boat and move aft, since weight in the ends of the boat contributes substantially to the pitching moment of the boat. Before beginning this project, you might also consider changing to lightweight batteries, etc, and removing the anchor and anchor rode to the bilges above the keel, if they are not already there. If you have a fixed bow roller, consider changing it for a removable roller that can be stowed with the anchor and anchor rode when it is not in use.

 

Before doing much interior renovation, I would make certain that the underwater surface of the hull is well-sanded to 320 all over, and 600 on the keel, rudder and forward 40% of the hull. Ultimately, you could fair the appendages and hull, using longboards, etc. This is a laborious process, but provides a major performance improvement.

 

Some previously mentioned getting the crew to lose weight. Probably not a bad idea on a personal level, but experience in one design keel boats suggests that high crew weight is probably faster, provided that everyone is mindful of their weight placement.

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As you constantly demonstrate.

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If the plywood bunk tops and other structural components are in good condition (no rot or delamination, etc), you can cut them away 2-3 inches from the glassed-in edges, and then use your foam core panels to fill in the removed area. This will avoid a lot of sanding, grinding and laminating, while achieving your weight-removing goal and preserving the present structural integrity of your boat.

 

I would first remove weight from the bow of the boat and move aft, since weight in the ends of the boat contributes substantially to the pitching moment of the boat. Before beginning this project, you might also consider changing to lightweight batteries, etc, and removing the anchor and anchor rode to the bilges above the keel, if they are not already there. If you have a fixed bow roller, consider changing it for a removable roller that can be stowed with the anchor and anchor rode when it is not in use.

 

Before doing much interior renovation, I would make certain that the underwater surface of the hull is well-sanded to 320 all over, and 600 on the keel, rudder and forward 40% of the hull. Ultimately, you could fair the appendages and hull, using longboards, etc. This is a laborious process, but provides a major performance improvement.

 

Some previously mentioned getting the crew to lose weight. Probably not a bad idea on a personal level, but experience in one design keel boats suggests that high crew weight is probably faster, provided that everyone is mindful of their weight placement.

For me this changing the plywoods to remove weight is more of an extra task, something to fiddle with during off season... Maybe not so much effect on performance but should not hurt either..

 

Anchors are stored just aft of the keel. Bow roller, which is unbelievably heavy btw, is off the boat most of the time. Have to look at what to do with batteries...

 

Bottom/keel/rudder is faired and sanded smooth, paint system will be Durepox and final coat Durepox Clear (for easy cleaning). Polished finish on everything.

 

Could you be more specific on "major performance improvement" ? Just would like to get an idea what to excpect, especially that it will be months until I can splash the boat. Need to have some ideas to dry-sail with... :)

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Another pretty obvious improvemt for weight saving that I have been thinking about is changing the wire lifelines to, say, 6mm dyneema. Just need to figure out a best way to tension them. Lashing the other end would be easiest but I do not like the looks so propably will need to get some sort of turnbuckle that will be long enough to tighten the 40' long dyneema line.

 

Something like this:

606340.jpg

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My 40' floor boards are infused closed cell foam with an anti skid surface. If I take them all up and stack them in a pile my 13yr old can carry them, they're nuts light.

Put me down in the vacuum bagged infused foam fan club, I find it fascinating.

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Another pretty obvious improvemt for weight saving that I have been thinking about is changing the wire lifelines to, say, 6mm dyneema.

Yes it's a great way if you lose the turnbuckles ! Yuour so many years late to the game that most offshore regs have or are going back to uncoated stainless if your doing any racing otherwise go for it.. You tension then with an eye on one end and a lashing, simple.

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My rudder has a blunt trailing edge nearly an inch wide and I've been thinking about re-profiling it at my next haulout. Do you have a reference on that optimal bevel study?

 

This stuff goes way back. NASA technical note 2074, 1950, covered it pretty well.

 

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930082748.pdf

 

I had a similar situation and faired the keel, written up here:

 

http://www.practical-sailor.com/issues/37_67/features/Fairing-the-Keels_12039-1.html

 

Note that it also had the effect of lengthening the keel about 10 inches. With that blunt an edge there WILL be a change in balance. In my case, since there was a pre-existing balance problem and a slight shortage of lateral plane (sails had been enlarged), so this was very beneficial. Perhaps the best $$/speed project I have ever done. Great project.

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Another pretty obvious improvemt for weight saving that I have been thinking about is changing the wire lifelines to, say, 6mm dyneema.

Yes it's a great way if you lose the turnbuckles ! Yuour so many years late to the game that most offshore regs have or are going back to uncoated stainless if your doing any racing otherwise go for it.. You tension then with an eye on one end and a lashing, simple.

 

Thanks for heads up, I had missed that one. I was sure dyneema lifelines were still ok. Most of the races we do are OSR Cat 2 or Cat. 3 w/ Liferaft...

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My rudder has a blunt trailing edge nearly an inch wide and I've been thinking about re-profiling it at my next haulout. Do you have a reference on that optimal bevel study?

This stuff goes way back. NASA technical note 2074, 1950, covered it pretty well.

 

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930082748.pdf

 

I had a similar situation and faired the keel, written up here:

 

http://www.practical-sailor.com/issues/37_67/features/Fairing-the-Keels_12039-1.html

 

Note that it also had the effect of lengthening the keel about 10 inches. With that blunt an edge there WILL be a change in balance. In my case, since there was a pre-existing balance problem and a slight shortage of lateral plane (sails had been enlarged), so this was very beneficial. Perhaps the best $$/speed project I have ever done. Great project.

Thanks, Drew.

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I had a similar situation and faired the keel, written up here:

 

http://www.practical-sailor.com/issues/37_67/features/Fairing-the-Keels_12039-1.html

 

Note that it also had the effect of lengthening the keel about 10 inches. With that blunt an edge there WILL be a change in balance.

 

I read that article when it was published and found it very useful. Thanks!

 

I worried about the cantilever that was formed, particularly at the bottom of the keel -- 10 inches longitudinal on 1 inch athwartships. Apparently the inch-wide bond is sufficient since your new trailing edge hasn't broken off to leeward.

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Another pretty obvious improvemt for weight saving that I have been thinking about is changing the wire lifelines to, say, 6mm dyneema.

Yes it's a great way if you lose the turnbuckles ! Yuour so many years late to the game that most offshore regs have or are going back to uncoated stainless if your doing any racing otherwise go for it.. You tension then with an eye on one end and a lashing, simple.

 

Thanks for heads up, I had missed that one. I was sure dyneema lifelines were still ok. Most of the races we do are OSR Cat 2 or Cat. 3 w/ Liferaft...

 

then skip the dyneema.

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I had a similar situation and faired the keel, written up here:

 

http://www.practical-sailor.com/issues/37_67/features/Fairing-the-Keels_12039-1.html

 

Note that it also had the effect of lengthening the keel about 10 inches. With that blunt an edge there WILL be a change in balance.

 

I read that article when it was published and found it very useful. Thanks!

 

I worried about the cantilever that was formed, particularly at the bottom of the keel -- 10 inches longitudinal on 1 inch athwartships. Apparently the inch-wide bond is sufficient since your new trailing edge hasn't broken off to leeward.

 

 

1. The keels are not very deep, only about 16 inches.

2. It is NOT just a 1-inch bond. I tapered it 12:1 and glassed it in with 3-4 layers of 17 oz. triax on all sides. It should be nearly as strong as the rest of the keel. Heck, I've put it in the mud a few times. I doubt I could budge it with a sledge hammer.

 

So long as you taper and glass it like any large area repair, it should be VERY strong. If you just glue it on, not so much. Really, the hydraulic load is very small, it is only grounding you worry about.

 

These are transom extension I added a few years ago (also a speed boost). 4-inch tapers inside and out. It is the taper/scarf that gives the dependable strength.

 

Transom+after+trim+and+joint+grind.jpg

 

Transom+ready+for+paint.jpg

 

 

http://sail-delmarva.blogspot.com/2013/08/extended-transoms-process.html

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2. It is NOT just a 1-inch bond. I tapered it 12:1 and glassed it in with 3-4 layers of 17 oz. triax on all sides.

 

Well, that was not described in the article.

 

But yes, I did incorrectly think in terms of a deep keel as on a monohull.

 

I didn't intend my post to be an insult. Sorry about that.

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2. It is NOT just a 1-inch bond. I tapered it 12:1 and glassed it in with 3-4 layers of 17 oz. triax on all sides.

 

Well, that was not described in the article.

 

But yes, I did incorrectly think in terms of a deep keel as on a monohull.

 

I didn't intend my post to be an insult. Sorry about that.

 

 

No, I'm sorry, I didn't take anything as an insult. The "NOT" was only for emphasis. I didn't mean for it to seem as though I was yelling. No problem.

 

Yeah, articles get cut for length, often brutally.

 

---

 

Other than performance designs, it's common to see blunt edges, because they are easier to build, and to the eye of some buyers, more durable. The first is a lame excuse, particularly on a boat like the PDQ that really can be quite fast if kept light. It's actaully fairly weatherly now. The second is simply untrue IMO.

 

Forums posts are funny that way.