GB5508 Rebuild - Soma's Project

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soma said:
I'm not convinced that this is the winning solution, this may be an area we revisit, but for now we have "Plan A".
Fixed it for you.

Nice work Soma. Rational clear thinking, and looking outside the box. Interesting example of how looking at using non-marine or non yacht hardware is as good or better, and saves a "wheelbarrow" full of cash. The fact that the owner (who lets face it, will push that button whether that foil is loaded or unloaded......) is bought in...... makes this the best plan.

Fair winds to you all for the completion of this project. I still believe that the Irens hull lines for this era of Gunboats is/was some of the prettiest yet potent lines ever drawn. Supermodel meets racehorse vibe. (Just need to to pretty up that Longeron.......)

 

randii

Member
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Sacramento area
Ah - below decks and inside makes a lot of sense. Keep them out of the salt spray and they might last for a good long time (and if they do start rusting you won't see them!)Heck, I'd carry a spare winch if it wasn't so heavy. 104 lbs! Yikes.
I've used similar winches in pretty nasty environments on a 4x4. Installing some sort of 'drip leg' (fairlead/pulley?) downhill of the winch and its attachment point on the board should help keep seawater off the winch some... especially if the line pivots under load, which would make a heck of a squeegee. Some means of freshwater rinse is probably worth adding to the maintenance checklist, though rinsing things inside the hull has its own complexities.

As for weight -- this winch is rate for 16.5k, and Warn is not known for skimping on ratings or safety factors. If you can feed the winch with sufficient power (fat cables), the failure modes are likely to be motor or contactors. The motor (https://www.amazon.com/Warn-68773-WARN-Winch-Motor/dp/B002DTYBWO is 16 pounds separate, and the miscellaneous electric bits will be even lighter. Pack a few spare bits and put a full spare winch in the sailbox on the trailer during sea trails. :p That'd be some trailer!

Randii

 

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soma said:
Hmmmm...what don't you like? We are going in a totally different direction than the stock 55 with our longeron but I'm curious what your objection is. 

We are doing a well for the furler to get the solent tack right down to the "deck". It'll also be similar to the Lorima style longeron with a big triangular cross section. If you've seen the MC2-60 or Fujin you know what I'm talking about. See below. 

View attachment 282079

View attachment 282080
Soma, I recognise the substantial loads, and the need to structurally tame them, both vertically and horizontally.

There are many pretty sailboats out there with dodgy Rhinoplasty up front.

And yes your proposal is an improvement on earlier generations......I like the sound of the endplate - for peformance gains - will this be soild structure or a 3Di soultion? I hope (but think unlikely) that the furler drums can be sunk into the beam to truly clean up the airflow.

It's just the cantilevered section out front - just screams I-Beam/RSJ or precast at me, and somewhat an afterthought, or moment when the budget got reined in...... particuarly when viewed in context against those svelte hulls.

In fantasy boatyard world, I would go for slimmer section that is stayed 3 ways - I know this has knock ons for the anchor storage just behind the front beam - but for that I would have such a heavy item stowed further aft (nearer to overall COG - poking out the front face of the main beam/nacelle) and a Y-bridle system to bring its effective deployment back to the front beam. Save a bucket load of weight in that Longeron, add anchoring complexity (but hey, the amount of anchoring that these beauties do, is not extreme) but restore or regain some of those supermodel aesthetics.

Not trying to offend or stir anyone up. Will still follow this project with more than a liitle envy.

Fairwinds.

 

DDW

Super Anarchist
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Soma, looks good! You'll be wanting my new Grand Prix version of the Anomaly Headboard for that one. Saves 4+ lbs. 5 with the titanium block. 

 

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soma said:
Man, forgive the typos above. Sail, not sale. Effort used twice in one sentence. That "edit" option disappears quickly!
Thanks for the update Soma - keep em coming. Nice progress

Can you repost the two photos from #68 that refuse to load?

 

MDRMark

New member
soma said:
Man, forgive the typos above. Sail, not sale. Effort used twice in one sentence. That "edit" option disappears quickly!
Thanks for the update.

I'm curious what you are doing for vibration isolation on the fisher pandas.   As more and more folks move toward electric backed by gennies, I think we need much better vibration isolation.   Should be much easier with constant rpm generators that don't require a mechanical coupling to a drivetrain.  Theoretically, there is no reason the generators shouldn't be near silent other than a slight output of acoustic noise from the exhaust with negligable vibration transmitted to the hull.  

 

Zonker

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It's very easy to isolate little generators like that so you only hear the splash of the wet exhaust. I did the following on a 20 kW Kohler and you could only tell it was running by the indicator lights. Fisher Pandas - ugh.

- put them on soft mounts inside a sound absorbing box

- have a sound absorbing box that is reasonably air tight with an intake baffle

- put the box on a second set of soft mounts, the softer the better

- exhaust right at the waterline

Is that big carbon beam in the first picture built in a right / left C shaped mold and then taped along top and bottom flange?

 

Zonker

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Airbus has a new term I learned the other day. The CEO likes to say deliveries are "backloaded". That means late.

I shall have to save it for my project management reports.

 

Sailabout

Super Anarchist
It's very easy to isolate little generators like that so you only hear the splash of the wet exhaust. I did the following on a 20 kW Kohler and you could only tell it was running by the indicator lights. Fisher Pandas - ugh.

- put them on soft mounts inside a sound absorbing box

- have a sound absorbing box that is reasonably air tight with an intake baffle

- put the box on a second set of soft mounts, the softer the better

- exhaust right at the waterline

Is that big carbon beam in the first picture built in a right / left C shaped mold and then taped along top and bottom flange?
water stripping muffler is the go, will make any size gen set silent.

Water  blowing out the exhaust is so 80's

 
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Zonker

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Well in my defense that project was in 1991 and water separating mufflers were not in common use then!

 

mrybas

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soma said:
Overall, the project is going well. 

-We got heat set up in the tent this week. It's not below freezing yet but it's getting cold.

-The plan is to wrap up all major boatbuilding by Xmas. There'll be a lot of mop-up but (hopefully) the big stuff is over by then.

-The painters are doing great. We should have all exterior surfaces to finish primer by Thanksgiving. Then we move into the salon/galley, then head down below sometime in the new year.

-We've managed to hang onto the target of 7-9 guys aboard each day. Newport is crazy busy with boats trying to get south, but somehow we still had 7 guys aboard today. (Too many guys and everyone is tripping over themselves, too few and the project drags on too long and you end up with 20 guys on the boat at the end. Get on the throttle early and stay on it). 

-At this point, I am still saying that we are on target for a May launch. With that said, I know it's really easy to just backload the schedule and say "voila, we are on schedule!". When that fails, you just reschedule the launch and say, again, "Voila, we are on schedule". So for now (knowing that I live in a glass house) I'll stick with May. 

-The next big decision is whether to go for laminated glass ($$$), tempered glass ($$), or acrylic ($). Interestingly, the Gunboat fleet has chosen the heavy and expensive laminated glass route. It's not often that you opt for the heavy and expensive option. Usually, you pay a premium for the light option. I equate it to buying $5 sunglasses at 7-11 vs Maui Jims. 

-The Harken 65's @ 48v spit the line out at 2m/sec. That's sick. That's faster than the hydraulic 990's.

Stop by anytime. I'm there most days.
Made any decisions on type of glass or Acrylic?

What about coatings that reduce heat transmission to the interior of the boat?

http://v-kool-usa.com/

Or

https://www.huperoptikusa.com/marine/

These guys do lamy tempered glass with IR interlay but it costs an arm and a leg:

https://www.bentglassdesign.com/

 

Zonker

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soma said:
No one wants to install acrylic
Huh? It's not hard at all. Remove paper in bond area. Prep sand with 120, paint with some black super plastic paint to hide the bonding area. (Krylon spray paint actually works well). Use Sika's guide to size bond size (thickness is absolutely key to success). Use small rubber spacers to ensure it doesn't get compressed during curing. Use Sika 295 for plastic, Dow Corning 795, GE Silpruf 2000. Sika 296 for mineral glass.  How to guide: http://www.westernmarine.com/acrobat/sik application guide.pdf  Use black foam rubber weatherstripping stuck to outside perimeter of the opening as a dam so you get a neater edge rather than smearing caulking everywhere.

We had 1m x 2m x 10mm thick front windows on our cat. The bridgedeck cabin was built very light so I suspect it was slightly flexy. Never had any leak for years. Replaced only after crazing after years in the tropics. Did it all myself and while competent, all I did was read Sika's guide.

Small commercial shipyards do it all the time themselves. They don't use a specialist firm. But they do use glass because class rules don't really understand plastic.

Acrylic is SOOO much lighter. Use a pretty dark tint - you'll see nav lights through them. 

You can get pretty nice marine roller blinds that work on angled windows:  https://www.solasolv.com/

The big tradeoff is lifespan versus weight. Plastic lasts maybe 6 years in the tropics uncovered. Glass lasts decades but the bond may need to be replaced in 10 years. Glass looks great forever, plastic, not so much.

 

mrybas

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soma said:
Yeah, I've installed acrylic windows before, too. It's not that hard. It's just...no one in Newport is willing to. There are folks in Florida, but by the time you pay for their travel to template, then again their travel to install, etc you end up bumping up to the range of the cost for glass. 
What are you figuring the weight savings is with Acrylic vs glass?

 

Foiling Optimist

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I'd be fascinated to hear what you're considering for thicknesses of glass vs plastic. Looks like window glass has a specific gravity of 2.5 where acrylic is 1.18, but my feeling is laminated glass is a lot stronger. I might be wrong though? I note Wikipedia suggests glass has a tensile strength range from 1000 psi to 2,500,000 psi vs acrylic's 10,000 psi but it can't be directionally isotropic for glass so this is a tricky question. I love acrylic for its amazing clarity but it's not chemically robust and does scratch way faster than glass.

 

Zonker

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Thickness depends on the span of the shortest panel. For offshore use, 10mm acrylic for 900 mm span is acceptable to me. If it was plain glass, probably 13-14mm would be required. If it's tempered glass, the strength is similar to acrylic.

For Class approved smaller ships, a short span of 1100-1200mm means a glass thickness of 19mm. And they still break on occasion even then. Class doesn't like tempered glass typically and doesn't give credit for the higher strength usually.

Weight savings - a 4'x8'x3/8" (10mm) acrylic sheet weighs 75 lbs. Glass is roughly double that as pointed out above. You'll probably use the equivalent of 2 sheets or more for all those big windows, so weight savings in the hundreds of pounds. I can put up with a few scratches for a few hundred pounds weight savings.

 

trackday

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Regardless of whether you choose Acrylic, glass or polycarbonate as your window material, you should comply with the rules for thickness calculations provided by ABS HSC or ISO/ CE.  Failure to comply with the established rules for thickness places you at risk of a rejected insurance claim should a window failure occur.  If you compete in a race where your vessel must be ABS or CE compliant, you could be prevented from racing if your windows do not meet the required S.F.

Once you establish the required thickness for the material of your choice, you may calculate the weight deltas

M

 

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