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Forestay fitting on small foiling trimaran


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I am preparing an A-class hull (GRP with carbon reinforcemants) to be used as centerhull on a small foiling trimaran, 5.5x6m,  sub 100kg, SA 14sqm (incl. 160mm mast section).

Was first into adding a second chainplate together with a short bridle but hesitated due to the one hand work inside, as the inspection port is only 125mm diameter and 40cm rear of the forestay. Removed foam and injected West Six-10 on the starbord side before changing my mind.

Will instead bolt an eyebolt directly in the fore deck with reinforcements under the laminate, eventually adding an alu bar lengthwise. The deck has a fatter, harder and carbon fiber reinforced(on inside layer) laminate than the hull sides. With 2 layers of epoxy glued 1mm G10 and an oblong alu plate plus an optional alu bar, to spread the load over a bigger area, this will work in my world. I have guesstimated load to be max 200kg. Will experiment with a stayed wishbone rig in order to lessen the forestay load on the hull.

Any other suggestions on fitting the forestay to the hull?

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däckskena.jpg

öglebult.jpg

detaljchainplate9.png

 

 

Windkniferigg.jpg

 

SEGELCOE_resultat.png

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Instead of the alu bar mentioned above a 80cm long 30x30x3mm square tube would save substantial weight. But probably only a squre plate as n the sketch above is enough?

detaljchainplate10.png

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I think you may pull a big hole in the foredeck.

To be safe I would be trying to transfer the load to the sides of the hull.

A carbon chainplate attached to a b/h and b/h laminated to each side , even if only half height would be what I'd be doing.

Make the chainplate so a fore and aft pin takes the forestay when the forestay thimble  fits into a slot cut in the chainplate. 

 

 

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24 minutes ago, The Mad Hatter said:

I think you may pull a big hole in the foredeck.

To be safe I would be trying to transfer the load to the sides of the hull.

A carbon chainplate attached to a b/h and b/h laminated to each side , even if only half height would be what I'd be doing.

Make the chainplate so a fore and aft pin takes the forestay when the forestay thimble  fits into a slot cut in the chainplate. 

 

 

^^ what he said

1. Pre-make a foam sandwich bulkhead with a carbon chainplate (carbon uni wrapped over stainless or titanium thimble).

2. Carefully cut away a square foot of deck centred on where you want the chainplate.

3. Glass in bulkhead tabbing front and back to side and bottom with bulkhead sloped aft in line with proposed forestay.

4. create bonding flanges to cutout edges

4. Replace deck inspection panel.

5. glass edges and fair.

 

 

  

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1 hour ago, revintage said:

 

Windkniferigg.jpg

 

 

draw out your COE and CLR vectors on this view not on the profile view (actually you need to use a combination of both).  The lateral separation of the contributing components means traditional COE/CLR lead ratios want work.

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I first was all into the double chainplate at first. Then remembered the solution made on the sister hull (also trimaran) with a sheet track above and another under the deck. He didn’t even add the 2mm G10 that I suggests. It is rigged with 20sqm SA.

I am open to all suggestions. Actually made a few suggestions in Fix it, but it was probably the wrong place as noone dared to answer:rolleyes:.

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11 minutes ago, SCARECROW said:

draw out your COE and CLR vectors on this view not on the profile view (actually you need to use a combination of both).  The lateral separation of the contributing components means traditional COE/CLR lead ratios want work.

The sketch with COE is only preliminary, will be determined later. But empirical tests has shown that the concept is not that critical, ref. Doug Halsey’s Broomstick.

F47BDB10-773C-4F6B-B28B-8CA4DC750E15.jpeg

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Thanks for the very serious advices. It is of course that way it should be done. 

If we look at it from another view, a 800mm long  30x30x3 would give a load of ca 1kg/cm2 to the deck if we hypothetically assumes 200kg on the forestay and no bending of the square tube(going up to a 30x60x3 would have miniscule bend). With 800x 100mm 2mm G10 epoxied to the underside of the deck,  the load will be even further spread. The question is then if the whole foredeck will be ripped off the hull?

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Thanks for the very serious advices. It is of course that way it should be done. 

If we look at it from another view, a 800mm long  30x30x3 would give a load of ca 1kg/cm2 to the deck if we hypothetically assumes 200kg on the forestay and no bending of the square tube(going up to a 30x60x3 would have miniscule bend). With 800x 100mm 2mm G10 epoxied to the underside of the deck,  the load will be even further spread. The question is then if the whole foredeck will be ripped off the hull?

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Not quite sure I would put so much localised pressure on the deck. Far better to cut a hole in the side of the boat and insert a proper bulkhead, the cutting of a decently large panel in the side is far easier to repair and you will know that you have a nice light weight bulkhead in there spreading the load right across the whole structure.

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3 hours ago, Waynemarlow said:

Not quite sure I would put so much localised pressure on the deck. Far better to cut a hole in the side of the boat and insert a proper bulkhead, the cutting of a decently large panel in the side is far easier to repair and you will know that you have a nice light weight bulkhead in there spreading the load right across the whole structure.

Spreading the load over 80x10cm 2mm G10 and then 80x3cm alu square tube shouldn’t be so “localised”. What might happen is that the whole deck rips off.

Anyway, will not insert a bulkhead or cut more holes. Will add the reinforcements through the present 140mm port.

Check the link to “Fix it” above: The present chainplate is capable of taking half of the upward load, obviously a similary built up reinforcement for a chainplate on the other side of the hull will take the same. The added compression force from each side will be taken up by the proposed alu rod.

Want to keeping it simple.

The sketch is one of the proposed solutions based on using the chainplate fittings in combination with some load on the reinforced deck.

 

 

detaljchainplate5.png

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For this to work you will have to have minimal to no gaps at the ends and to the section up to the deck, are you sure you can locate and set the whole sytem through the cutout with minimal tolerances. Any compression of the deck and side panels as you screw the locating bolts in tight will probably weaken or possibly damage the surrounding joins and materials. 

From experiance this would be far easier as a bonded in bulkhead. 

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I am aware of this. My idea was to make the horizontal rod adjustable to close any gaps. The vertical is easier as you can use a threaded M8 with nuts to set the tension.

You could skip the vertical coupling to the deck and only rely on the horizontal bar for taking the upward load. My guesstimate is that a 150mm long 25x25mm solid 6082 alu bar would take it even with a 8mm hole in the middle. The deck would then only need to take the for-aft force from an eventually misaligned eyebolt.

Below is an low weigth idea using a dyneema bridle through the hull keeping the outside chanínplates.

detaljchainplate2.png

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39 minutes ago, The Mad Hatter said:

A bit  like fitting truck tyres to a Ferrari.

Heavy, ugly and slow.

 

Interesting, please explain heavy, ugly and slow:rolleyes:! Instead of making snotty remarks, why not show how you did it, when building your lightweight trimaran?

Have you even done a weight calculation, FYI the alu rod would be 253 gm, can live with that. 

The easiest solution would be to add a chainplate opposite to the present and leave the compression rod out. Then add a 45 degree bridle to the chainplates above deck and let the deck take the horisontal compression. Vertical load will actually be a close to the same as on the A-class

detaljchainplate3.png

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I suppose the closest solution that I have built for this particular application would be the side stay fittings on my F85SR.

The forestay on the F85  is different because it is part of the carbon socket that takes the carbon spinnaker pole.  Building that that was a more interesting  because I made a collapse able mandrel to make the carbon socket. I may have picks of that too but  it is not really applicable for what you are trying to do.

When I get a chance, maybe later this evening,  I will see if I can find relevant picks , I think I backed them up before my  old laptop died..

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TMH, pls see my edit above. F85 is another creature made for open sea. Remember we are talking 14sqm and 100kg for flat inlake speedsailing instead of 42sqm and 800kg at sea.

Would anyway be interesting to see your picks if you find them.

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The guys telling you to resin in load spreading material to the sides of the hulls are spot on, from experience with mucking around with a light A Class that I broke a hull in half at the main beam I can tell you the existing deck was never designed to handle any load leading directly up. The hull you have is designed to use the side of the hull as the point where half the fore mast load is taken. As the others have said if you resin in carbon layers down the sides of the hulls, across the underside of the deck making it all one piece you will ensure your fitting stays in the hull, 14 sq metres of sail doesn't sound like much but when you bury that bow into a small wave there is a lot of pressure on that hull that in its entirety probably only weighs 25kg. Anyway good luck with your project and hope you understand I'm not being a hater 

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3 hours ago, revintage said:

TMH, pls see my edit above. F85 is another creature made for open sea. Remember we are talking 14sqm and 100kg for flat inlake speedsailing instead of 42sqm and 800kg at sea.

Would anyway be interesting to see your picks if you find them.

I agree,  but a scaled down version both in size and laminate would be the a really neat solution.  The Mad Hatter  was my 16nth boat build and I promised the misses it would be my last so I took thousands of pics. If I find a backup  I should have something on it.  

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I had a look at your edit and it is better because the compression load on the deck could be managed in the height selection of the bridle and the load will be transferred to the side of the hull where it needs to be. It is also light weight.  However bolts in an area of hull had has not been planned to have bolts can be an issue because they can crush the lightweight foam.  Also they often find a way of leaking. Any attempt to tighten them to minimise leaking will also crush the foam it not already and the leaking will just get worse. I have also built small Off The Beach cats  and it used to be a challenge until I gave up on that type of  bridle fitting and went to building them into the bulkhead.. .  The neatest solution is a simple composite chainplate type fitting on a part bulkhead.  Given the size of your project it could probably  be done with just 450gm double bias glass. Some uni carbon in the chainplate would be nice but you could probably get away without it. If you can't source  corecell foam you could use 4mm gaboon ply as the part bulkhead core as it will be only a small section and it would allow a reduction in  the glass laminate. Probably drop down to 200gm glass instead of 450gm. Foam just would be better.

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As a rule of thumb uni carbon has the same tensile strength as stainless steel for a given cross sectional area but 1/7 of the weight.

You could use that to help scale the F85 chainplate down  for your application and unlike the F85 fit it to the part bulkhead  before installation. 

See pics below. The chainplate fits into the slot in the B/H and angle for a straight pull to the hounds and laminate in with 450gm double bias.

I was sure that I took pics from the inside after fitting but cant find them.


The last pics shows it fitted during the fairing and painting stage.  (Pencil showing hollows that need to be fixed. ) 

Chainplate bulkhead.jpg

chainplate in hand.jpg

chainplate with peel ply and tape.jpg

painting 008.jpg

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On 7/3/2019 at 4:33 AM, The Mad Hatter said:

However bolts in an area of hull had has not been planned to have bolts can be an issue because they can crush the lightweight foam.  

Have dumped the idea of a deck forestay fitting. When using a 45 degree bridle as in the sketch with the assumed 200kg load you will have a 100kg vertical load on each hull side, together with a horizontal component of the same magnitude from both sides. Lots of compression at the deck level!  Not sure how high I can go with the bridle yet, as the jib tack can not be placed to high.

If you take another look at the right hand side chainplate you will see that I have (carefully) removed the foam in the actual hull area and injected West epoxy in the cavity. This was the first thing I did when I started the chainplate project, before getting the deck idea. There is also a 2mm G10 plate on the inside to build some thickness. To complete the buildup my idea is to add three layers of 5cm wide strips of 220gm carbon fiber together with West 105/205. Maybe adding carbon fiber all the way to the left is a good idea. See attached and modified sketch. 

Would this be sufficient?

 

detaljchainplate11.png

carbon.jpg

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On 7/3/2019 at 1:55 AM, ziper1221 said:

What make is that hull? It looks nice

No idea. The A-cat donor was with bolted cf beams and cf mast. Seems quite dated though.

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When keeping a structure in column to resist compressive forces making it thicker is the best way.

 One layer of 6mm foam and a layer of carbon would add around 6.2mm which would work far better.

Much better still would be if the layer of foam was on its edge and wrapped in carbon.

When I started building the Mad Hatter I already had enough 8mm core cell foam for the hulls but 10mm was specified. I worked out the hulls would be twice as stiff with the 10mm. It is not a linear  relationship between stiffness and thickness so I bought the 10mm foam.

If you want to keep it in column make it stiffer by making it thicker.

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Random idea here, create a 2nd chain plate and then have a split forestry from say 2m up from the deck. Create a fixed tube from that point down to the deck to take the jib, some of the early F16’s had their jib this way and it worked well.

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looking at your last drawings, if you estimate the total load is 200kg vertical it will be 170kg on each side with the 90° angle. is that a big improvement? 

and the total load on your mast will be 14 x 80 kg= 1040 kg on the mast at 25 kn wind You should at least double that number for safety reason.

we are not even talking of that time when you will drop speed from 20kn to almost nothing when falling from foiling....

Epoxy-Carbon a 100 mm high layer of foam or plywood on the edge as Mad Hatter told you and go for a center chainplate for the jib. 

you could go for another place to hold the mast at the front of hull with a hole  with carbon also. 

look at the photos for the ring fitting (thank you VMG) and for the hole to hold the mast

all these things could be done quite quickly if you go for it

and good on you for that project 

IMG_0072.JPG

IMG_0071.JPG

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7 hours ago, Waynemarlow said:

Random idea here, create a 2nd chain plate and then have a split forestry from say 2m up from the deck. Create a fixed tube from that point down to the deck to take the jib, some of the early F16’s had their jib this way and it worked well.

Wayne,

Good point.  Now ain't that a blast from the past. The jib could go down to the spinnaker pole with a 10mm compression strut up to the bridle.  If that concept was applied here minus the strut  the deck fitting would be only  taking the tension in the luff of the jib  while the bridle takes the full  load of the rig. Not a bad solution but if it was my boat I would still go the carbon chainplate &  b/h route. Just too neat to pass up.

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8 hours ago, Waynemarlow said:

Random idea here, create a 2nd chain plate and then have a split forestry from say 2m up from the deck. Create a fixed tube from that point down to the deck to take the jib, some of the early F16’s had their jib this way and it worked well.

Wayne,

Nice and simple solution, following the KISS principle.

I use this on my  3m wide Nacra 5.5 catamaran with F18 jib and spi pole. 

Did some rough ballpark calculations of the horizontal total compression:

90 degree bridle with 18cm hull width, is at 9cm height and compression 200kg.

20cm height, 95kg compression

25cm heigth, 75kg compression

30cm height,  60kg compression

200cm height, 10kg compression

Probably the tube will not even be needed, as the jib tack should be attached a little higher, hopefully in the bridle split, to get the correct angle for the sheeting car&track mounted at the front of the beam.

My guesstimate is that 75kg compression, half from each side, will not harm the deck, even without reinforcements.

Will do a provisional set up with beams and mast in a few weeks to find out actual jib tack height. 

 

 

 

detaljchainplate12.png

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I haven't got much pics of the build but you can look at the" new trimaran under 20" thread for photos 

My motto in boat building:don't pray the Lord, spray the load

Please put pics of your build as it goes as I don't facebook

 

 

 

 

 

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1 hour ago, RV64 said:

I haven't got much pics of the build but you can look at the" new trimaran under 20" thread for photos 

My motto in boat building:don't pray the Lord, spray the load

Please put pics of your build as it goes as I don't facebook

 

 

 

 

 

What is your nick on BD?

I actually have a build thread on BD that I am updating once in a while.

https://www.boatdesign.net/threads/windknife-trifoiler-build.61518/

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On 7/5/2019 at 1:14 AM, Waynemarlow said:

Random idea here, create a 2nd chain plate and then have a split forestry from say 2m up from the deck. Create a fixed tube from that point down to the deck to take the jib, some of the early F16’s had their jib this way and it worked well.

Wayne,

I initally forgot to check the angle of an original A-cat forestay. Calculated the horizontal force vector and it should be on par with the force from one side of a 20cm high bridle.  

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I would check that, as a 20cm bridle would be a lot tighter angle than the conventional two stay set up. A lot of the two stay setups was not only convenience of design but designed to stiffen up the structure of the boat and prevent twist of the hulls.  A simple calculated loading is not going to take into account of the pressure exerted by the twist of Hull once one hull is out of the water, but also that of 95kgs of fat lardy arsed skipper out on the trapeze + some 45kgs of pull on 10:1 main setup.

Mmmmm don’t want to really say this openly here on SA but a certain poster with the initials DL had a calculation that could be used to give approx. loading for the wire sizes, perhaps you could PM him as it would be pretty close to what you will see on the loading point.

I run my present AClass with a split stay about 3 metres up to a single stay as I run a spiny as the conventional stay position would prevent the spinny folding through the gap on gibe. That would make the loading even higher than conventional. So far I haven’t broken it, touch wood.

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Hi Wayne,

Recalculated and the bridle of an A-class with 230cm between chainplates and the split to single  at 300cm as on your cat, equals the angles of a 18cm wide and 23cm high bridle.

With the A-class forestays going all the way up to the hounds, the 18cm wide bridle has equal angles with something like 50cm height.

 

 

 

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On 7/1/2019 at 12:02 PM, The Mad Hatter said:

I think you may pull a big hole in the foredeck.

To be safe I would be trying to transfer the load to the sides of the hull.

A carbon chainplate attached to a b/h and b/h laminated to each side , even if only half height would be what I'd be doing.

Make the chainplate so a fore and aft pin takes the forestay when the forestay thimble  fits into a slot cut in the chainplate. 

 

 

 

Have spent some time to find out how to add a bulkhead from the 140mm dia inspection port, placed ca 30cm behind the bulkhead.

As this is a Frankenfoil build I want to use as much inhouse material as possible.

So I invented my stash for things to use:

5m 50mm wide woven 220gr carbon fiber strip unfortynately not uni or diagonal.

4mm high density PVC foam

30x30x2mm alu L-bar

8x1mm SS tube

West G-Flex

West Six-Ten

West 105/205

USB-camera with LED light

 

1 As the rear of the bulkhead isn´t reachable through the 140mm port hole when in place, alu L-bars can be  glued to the hullsides with G-Flex using the old chainplate holes as guides. The alu must of course be isolated from contact with carbon fiber.

2 First make a template and cover the bulkhead with carbon.

3 The chainplate can be made by triple-folding two 50mm carbon fiber strips over the short 8x1 stainless tube and then unfolding them and spreading them out on both sides of the bulkhead. Will use two shackles outside of each other on the same pin, one for the  forestay and the other for the downhaul and tack arrangement. 

4 Take up a  hole in the deck of ca 15x20mm to let the chainplate out and at the same time remove the foam from the deck laminate around this area.

5 The bulkhead will then be glued in place against the L bars and carbon strips be added as bonding flanges at the reachable side.

Wonder how many layers of 220gr strips are needed on the bulkhead and as bonding flanges?

Should the bulkhead also be with bonded flanges up against the deck, RED line, in that case it will only be doable from the rear side?

Max height of the bulkhead with chainplate is just below 140mm to get it through the port, will leave a slot down to the horizontal bulkhead below, though.

You might think that this seems elaborate but this is a working method that I will feel comfortable with.

Hope the simple sketches are understandable.

bh2.png

bh.png

bh4.png

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Also thought of using only one triple folded carbon strip, unfolded stright down on each side of the bulkhead, glued under the bulkhead carbon fiber?

bh3.png

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I would coat the al angle with packing tape and use it as a mould to make the forward flanges.

I have bonded to aluminium before by sanding "wet and dry" with neat epoxy and 80 grit paper and it does stick but I've never been entirely happy with it. 

If you use the aluminium  just as a mould then you wont have to worry about corrosion  and get a better bond.The shiny  packing tape just ensures the carbon angle will release from the mould.  2 or 3 layers of carbon will make a very stiff angle once the resin has fully cured. I've made a lot of carbon tubes and they are always a bit floppy at first but rock solid several days later. So you may want to make the angle a little in advance.

When glueing in place make sure you sand well and do not touch the sanded surfaces with bare hands. The oil from your hands can undermine the bond.  I use Nitrite gloves because unlike latex gloves the resin will not penetrate.

The other point is the SS tube will make  rust stains if left in contact with the carbon. If you have any glass wrap it in glass first to  minimise the chance of rust stains on your deck. If my boat I would coat a SS or alloy tube in candle wax , wrap a dozen layers of 200gm glass, compress the layup by spinning in a drill and applying pressure as it spins with free hand to make a glass tube and use that instead of the SS tube.

I like the idea of unfolding the carbon or using another method to increase bonding surface area. A good reason to also stagger the carbon taping to the sides of the hull.

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Good idea, as I have 50mm wide CF strips, I can make 25x25 mm carbon L-bars with the 30x30 alu bar inner corner as mould. Will then  use the old chainplate bolts to fix them at the right place and angle. This will move the new chainplate 20mm to the rear, but this is no problem as I see it.

Still not sure how many layers of 200g CF I should use for the bulkhead sides, but my guess is that two will do. Will lay front and rear of the bulkhead at the same time, wrapping the cloth around the bottom end. Will buy some more and wider cloth for this and use the 50mm strips for the chainplate and as bonding flanges.

 

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IMG_0181.JPG.2c06941798b81a7e7a10f60763f9bd8b.JPGi was going to write the same as Mad Hatter...

i also thought that you could reuse the one off cut of the hole to stiffen you deck  like this (sorry for the rough sketch not to scale) 

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5 hours ago, RV64 said:

i was going to write the same as Mad Hatter...

i also thought that you could reuse the one off cut of the hole to stiffen you deck  like this (sorry for the rough sketch not to scale) 

Great minds think alike ;-) . Anyway the cut out from the hole is also a foam laminate, but the idea is good, will instead use two layers of 1mm G10 in the area.

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On 7/1/2019 at 8:02 PM, The Mad Hatter said:

I think you may pull a big hole in the foredeck.

To be safe I would be trying to transfer the load to the sides of the hull.

A carbon chainplate attached to a b/h and b/h laminated to each side , even if only half height would be what I'd be doing.

Make the chainplate so a fore and aft pin takes the forestay when the forestay thimble  fits into a slot cut in the chainplate. 

 

 

Agreed

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Cleaned up the inside where the bulkhead will be placed. No easy task to work with the Dremel from a small hole 35cm back, not seeing what you do. Still waiting for the web camera that will lift me out of blindness. Will be no problem to sand the areas to be glued anyway.

As the hull/deck corner for some reason is very weak, I will add some CF before fitting the bulkhead and also add a G10 plate on the right side and to the deck to build up thickness.

 

IMG_4135.jpeg

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You may be disappointed with the web camera.  I had some really difficult tasks inside the floats on my build and bought one to help me see while working.

It didn't.  

Without being able to see while working, getting it right  just took up a lot of time. I ended up  replacing the camera with  very slow hardener and a lot of patience.

Hopefully you will be lucky and get a much better camera.

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This is how I laminated made front bulkhead by making a temporary mold for making a glue flange.

http://f32thriller.blogspot.com/2015/05/glued-front-bulkhead-half-in-place.html

I did use a mirror to look around the corners and sometimes I just did it on feeling and did take a picture later to see if I missed something.

Stay from the metals and bold's is my opinion.

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Working in that confined space would it help to run two temporary parallel dowels from side to side through the hull at the location of the proposed bulkhead. This would provide a consistent position to work with and rest your template and final bulkhead against and once the bulkhead is tacked or taped in place the dowels are removed and the holes sealed. It’s tough to work by feel.

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14 hours ago, revintage said:

Cleaned up the inside where the bulkhead will be placed. No easy task to work with the Dremel from a small hole 35cm back, not seeing what you do. Still waiting for the web camera that will lift me out of blindness. Will be no problem to sand the areas to be glued anyway.

As the hull/deck corner for some reason is very weak, I will add some CF before fitting the bulkhead and also add a G10 plate on the right side and to the deck to build up thickness.

 

IMG_4135.jpeg

Take the deck off first

 

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On 7/12/2019 at 1:26 PM, cyclone said:

Working in that confined space would it help to run two temporary parallel dowels from side to side through the hull at the location of the proposed bulkhead. This would provide a consistent position to work with and rest your template and final bulkhead against and once the bulkhead is tacked or taped in place the dowels are removed and the holes sealed. It’s tough to work by feel.

That was actually my plan! By running a pair of M6 threaded rods covereed with brown tape through the old holes for the chainplate at the left and drilling corresponding holes at the other side I will get the support needed.

Didn´t get the camera yesterday so decided to go blind and do the reinforcements on the right side, where I about a week ago injected epoxy in the sandwich after having removed foam.

First a plate af 1mm G10 and upon that two 5cm wide carbon fiber strips. 

Don´t worry about the dust, I carefully sanded the actual area with 80 grit paper and cleaned with acetone.

Have also laid a plastic bag upon and compressed the pieces by hand to get everything as flat as possible.

Have also built the a sandwich for the bulkhead from things I had in the workshop. On each side of 10mm Divinycell I glued a sheet of 1mm G10. Weigths a little more than CF but will probably be light enough.

 

 

G10.png

CF.png

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Some peel ply over that would make it a little easier to be certain of a good bond later.

I still sand once the peel ply is removed but there is no amine blush to content with as it is on the peel ply which is removed.

The peel ply tends to keep the fabric below the upper surface of the resin and not much sanding is needed, so you don't cut into the fabric when you sand.

I first used it on some 32ft cedar strip catamaran hulls I built in the late 80s and loved it. 

I used peel ply on every part on my F85. In many cases applying the peel ply properly was the hardest part, but well worth it.

There are lots of claimed ways of removing amine blush and over the years  I've tried them all. In my view peel ply is the best because it avoids the problem all together.

 

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Mmmm not great, there’s a technique called New Zealand prepreg, that of making all your layers up on a bench on top of a piece of plastic bag or such like. Top layer ( peelply ) on the plastic first and then build up your layers wetting them out carefully but not excessively as working on a flat hard surface you can use a plastic scraper ( go to an auto body materials shop and they are a few pence each) to really compress the layers and ensure minimum resin. Once you have all the layers wetted out, lift the plastic off the bench and cut with a pair of scissors exactly the size of patch you need.

Now you have say 4 or 5 layers all very neat and tidy wetted out cloth ready to go onto the surface. Now roll the patch over the plastic, put a pencil in the middle, you can now lift and move the whole patch through the cutout easily. Position it on the prepared and wetted out surface you want the patch to be on from a corner. Roll it out along the surface and you are pretty much done in less than a few minutes.Remember to put a bit of silica or micro fibres into the resin on the inner hull surface to prevent slumping of the resin and fill the weave voids to gain maximum adhesion. You can remove the plastic at this point leaving the peel ply to retain the cloth shape. Now lightly run the plastic scrapper along the patch to ensure adhesion just once, anymore and you end up disturbing the layers of cloth. 

You might need to experiment a bit but I’m not sure you will have enough strength in such a confined area to dislodge the peel ply once the resin has gone off, if it is a problem then just use the plastic and peel that off whilst wet.

Job done.

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On 7/12/2019 at 10:01 AM, mowgli said:

This is how I laminated made front bulkhead by making a temporary mold for making a glue flange.

http://f32thriller.blogspot.com/2015/05/glued-front-bulkhead-half-in-place.html

I did use a mirror to look around the corners and sometimes I just did it on feeling and did take a picture later to see if I missed something.

Stay from the metals and bold's is my opinion.

I am not really sure I got this, but are you making glue flanges externally and  then glue them and the bulkhead in place? If so, this must be less messy than using wetted cloth in many layers inside the hull. 

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Added a pair of wooden dowels through the old chainplates holes to be used as guides for the rear glue flanges and the bulkhead, see sketch . Also cut the  bulkhead to size after having made a cardboard template. Cut a hole in the deck for the new chainplate to protrude. Waiting for the chainplate core(tube/Divinycell/epoxyG10) glued to the bulkheadto cure, will be covered with 6 layers of carbon fiber tomorrow.

6dowel.jpg

8bh.JPG

recthhole.jpg

chcore.png

bhfl.png

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4 hours ago, Waynemarlow said:

Mmmm not great, there’s a technique called New Zealand prepreg, that of making all your layers up on a bench on top of a piece of plastic bag or such like. Top layer ( peelply ) on the plastic first and then build up your layers wetting them out carefully but not excessively as working on a flat hard surface you can use a plastic scraper ( go to an auto body materials shop and they are a few pence each) to really compress the layers and ensure minimum resin. Once you have all the layers wetted out, lift the plastic off the bench and cut with a pair of scissors exactly the size of patch you need.

Now you have say 4 or 5 layers all very neat and tidy wetted out cloth ready to go onto the surface. Now roll the patch over the plastic, put a pencil in the middle, you can now lift and move the whole patch through the cutout easily. Position it on the prepared and wetted out surface you want the patch to be on from a corner. Roll it out along the surface and you are pretty much done in less than a few minutes.Remember to put a bit of silica or micro fibres into the resin on the inner hull surface to prevent slumping of the resin and fill the weave voids to gain maximum adhesion. You can remove the plastic at this point leaving the peel ply to retain the cloth shape. Now lightly run the plastic scrapper along the patch to ensure adhesion just once, anymore and you end up disturbing the layers of cloth. 

You might need to experiment a bit but I’m not sure you will have enough strength in such a confined area to dislodge the peel ply once the resin has gone off, if it is a problem then just use the plastic and peel that off whilst wet.

Job done.

Will do this in a less sophisticated way using three layers of the 50mm carbon strips, after having glued the front glue flanges and the bulkhead in place. One 14cm length on each side from hull to bulkhead and one 15cm length from deck to bulkhead. As it is rather tight I can only work with one hand without seeing anything, but the pieces are small and the epoxy is curing slow. 

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If it was my boat I'd wrap  plenty of carbon over that fitting.

Much more than would be required to take the load while sailing. 

I'd be concerned about  knocking the fitting while moving the boat around onshore. While you will no doubt be very careful you can not control the action of others.

I'd want 2 to 3mm of carbon. I may even   build the deck up a little around it with a lightweight filler to reduce the chance of a direct blow.

 

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9 hours ago, The Mad Hatter said:

If it was my boat I'd wrap  plenty of carbon over that fitting.

Much more than would be required to take the load while sailing. 

I'd be concerned about  knocking the fitting while moving the boat around onshore. While you will no doubt be very careful you can not control the action of others.

I'd want 2 to 3mm of carbon. I may even   build the deck up a little around it with a lightweight filler to reduce the chance of a direct blow.

 

As I have 50mm wide 220gr carbon, I intend to triple fold two strips over the fitting and then unfold and spread the 50mm strips diagonally over both sides of the bulkhead. This would build something like 1,5mm. I could add a triple folded final layer with the strip unfolded and spread out straight down the bulkhead, thus adding 0,75mm. The fitting tube is 19mm wide. I will also remove the foam around the hole in the deck and fill with epoxy. Will of course build up with filler. 

I am not sure how to do then:

First option is to narrow the fitting tube to 16mm and use a shackle, on which the the 4mm Liros Static Pro forestay is  fitted with a Brummel eye splice.

The other option is to cut a ca 6mm wide slot through the tube and carbon,  in the middle of the 19mm wide fitting and line the eye splice with a stainless thimble to protect the line from shafing against the slot sides.

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When you look at how much weight would be added versus what a pain it would be to repair I would ad the final layer  for sure.

I would also use a thimble on the forestay.  Dyneema looses strength when it goes around a tight radius.  I know this from experience. 

The fitting is probably more robust 16mm wide than 2 x 6.5mm.  

 

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Got an unorthodox idea. After having made the third carbon strip to build up the chainplate to 9 layers, one could just drill a 5.5mm hole just under the tube and round off the hole upwards. It will then be place for a piece of Liros XTR slide protect and the 4mm Static Pro. This together with an adjustable loop like on the image I stole from Colligo would be a really low weight alternative. I use these loops with 5mm Dux on my widened Nacra 5.5 with F18 rig and the other dinghies I have. 

bh4loop.png

loop.PNG

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Be a little careful with the adjustable loops in Dyneema, they are really excellent if there is a constant tension on the splice, if there is any sort of slackening and jiggling of tension, the adjustable section will slip through the splice ( all my boats are now fully soft splices in dyneema and ropes apart from the diamonds on the masts ), the forestay is a classic " jiggler ". What I now have is a Brummel lock splice with an eye using a SS wire thimble and then use a multiple pass of a small diameter rope around the eye and in your case the SS tube, it allows easy disassembly and easy alteration of length with a simple hitch knot and then lock the tail off by passing it through between the passes of rope AKA Aussie style.

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Have never experienced  any jiggling, but warning taken. Have also used multiple pass small diameter together with a Brummel with  thimble on the shroud/forestay. If using XTR Protect(to avoid the risk of of chafing against carbon) inside a 5.5mm hole 4x2mm dyneema is possible but 3x2mm probably will probably work better and will have about the same breaking load as a single 4mm. About " then lock the tail off by passing it through between the passes of rope AKA Aussie style", I am not familiar with the expression. Image?

Have you ever tried dyneema for the diamonds? Have not either, but will try 4mm Liros Static Pro on my small cut down 10,5 sqm A-class main rig.

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On 7/14/2019 at 6:07 PM, revintage said:

I am not really sure I got this, but are you making glue flanges externally and  then glue them and the bulkhead in place? If so, this must be less messy than using wetted cloth in many layers inside the hull. 

No I make them internal with a temporary bulkhead with a big hole in the middel so I can reach the other side of the bulkhead and laminate against it. When this is dry you remove the temporary bulkhead and glue the real one in place and laminate the other side.

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10 hours ago, mowgli said:

No I make them internal with a temporary bulkhead with a big hole in the middel so I can reach the other side of the bulkhead and laminate against it. When this is dry you remove the temporary bulkhead and glue the real one in place and laminate the other side.

I was thinking along the same lines. I would have a layer of plastic over the temp b/h wrapping around it and secured with packing tape on the aft side. (The one you have easy access to.)  Tape  strips of plastic  down each fwd edge but back from the edge so when the plastic strips are  folded out they are in the place of the required carbon taping. Then I would lay up the carbon taping on the plastic strips attached to the temp B/H. Before putting in place I'd coat the area of the hull that was going to take the taping with a thin layer of resin and microfibre ( ie glue mix). (Think Wayne also mentioned this.) to help ensure no air gaps as vision not be great even if I could get a mirror in there.  What ever means to hold the B/H in place would be on the aft side, of course, so not in the way. Once the B/H was in place and secured I'd put my hand through the hole and fold out the plastic strips delivering the carbon taping just where it needed to be and then go over the plastic strips with a dry brush to remove any air and ensure a good bond. Once the resin is cured I'd undo the packing tape strip on the aft side of the temp B/H and remove it. Then I would peel the plastic that wrapped the Temp b/h  and the plastic strips on top of the carbon taping at the same time. I would have used and extra layer or two of carbon taping so it remains stiff enough to sand to ensure a good bond to the real b/h when it goes in. 

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  • 2 weeks later...

Looks like great fun. Lots of new ideas here.  My 1971 Cal Fuller wooden plywood A-cat with aluminum SP foils never broke yet.  I guess Cal's epoxy plywood was pretty tough.  (RIP Cal).  OOps 18 years ago.

 

See the thumbnail on foils...

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