GB5508 Rebuild - Soma's Project

ProaSailor

dreaming my life away...
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Does the aft face of the cockpit/aft beam just sort of terminate into the side of the hull? I'm sure if Dirk was involved he would have some sort of load path for it.
This may sound naive and is certainly tangential thread drift but...  Yeah, how does that aft crossbeam work?  (structurally)

Same question for the GB 68 and other big cats that appear to avoid the deck-level bulkhead on the aft beam, so commonly found at the forward beam connection?

What I need for a big proa is two aft crossbeams like this...  I have sketches but would love to see how it's done on a GB?

View attachment 281164

 

Rasputin22

Rasputin22
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I think you forgot your sarcasm font...

In case you didn´t: 
Oh, I thought that maybe you meant that there were three unfinished boats awaiting new owners to complete like at Gunboat. First one looked great but things have gone very quiet since its launch. Shouldn't things go faster with repetition?

 

sail(plane)

Anarchist
688
106
Oh, I thought that maybe you meant that there were three unfinished boats awaiting new owners to complete like at Gunboat. First one looked great but things have gone very quiet since its launch. Shouldn't things go faster with repetition?
I meant that this thread is as interesting as the inside view of the Four Carbon Cutters. The photos, the trade-offs, the explanations

 

Monkey

Super Anarchist
10,897
2,521
soma said:
FWIW, there are 2 more unfinished hulls in NC. One is trash, but the other is in a great state of completion for completing. The tooling is also still down there.
Just curious, but why is one trash?

 

Rasputin22

Rasputin22
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Thanks Soma, so do the boards float up or can you rig that WARN winch to pull the board up under load as well as push down? Have you ever seen the SIG 45 system of using ANTAL line drivers on an endless system to do the same thing? Harken has line drivers similar to the ANTAL and I've been considering using them but way pricier than the WARN system. I'm going to the Newport Show to hopefully see the Rope Eye constrictors that I have been bugging the guy in Estonia about but can't seem to get a straight answer from him. Neither can Harken. Maybe you saw his answer to me on his Facebook page on the subject, 'Hot out of the oven!' He has been saying that a year now...

 

Rasputin22

Rasputin22
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Soma 

   Yeah, when I spoke with Harken yesterday, they mentioned that they now have a larger capacity line driver but I bet you could buy both the WARNs for the price of one Harken. Hope I can buy you a beer in Newport during the show. I'm bringing my client for a 50 cat and having him fill out his wish list on hardware for his next boat. Also going to visit our sparmaker while in town. I'll send you a PM.

 

Rasputin22

Rasputin22
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Tent! What tent? I'll find it for sure. Look forward to finally meeting you. How is your spar search going for SOMA?

 

bushsailor

Anarchist
693
193
QLD Australia
excellent thread. Thanks Soma.

Only comment I have is The open transom thing is dangerous.

It needs a door or step at least. A wave hitting someone at 20kn can punch them straight out the back.

Keep us updated about the warn system, very interesting.

 

PIL66 - XL2

Super Anarchist
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Stralya
soma said:
Fair point. I've put washboards on 2 of the 55's already. We haven't committed to them yet on this project yet, though. One reason is we should be sitting about 8" higher aft. Another reason we don't have washboards is we don't have engine rooms in back like the other boats. We still have the central, inside helm, so if things get sporty you can retreat to the wheel. But we may add washboards yet. 
A couple of removable nets for those days would work

 

Zonker

Super Anarchist
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I think that those Warn winches will last about 2 years in tropics before the powercoat flakes off and it starts rusting (steel) or corroding (aluminum casting?)

The IP 68 rating is better than any windlass however. Hope I'm wrong.

 

SCANAS

Super Anarchist
6,727
448
Brisbane
I think you’re underestimating the Warn’s. They have been known to provide 20yrs service bolted to the front of cars & trucks that live on the beach ( not coastal, driving on the beach everyday ) or worse, in coal mines. 

Carry some spare solenoids, make sure the drain location is facing down & repack it with marine grease. 

 

Sailabout

Super Anarchist
I think that those Warn winches will last about 2 years in tropics before the powercoat flakes off and it starts rusting (steel) or corroding (aluminum casting?)

The IP 68 rating is better than any windlass however. Hope I'm wrong.
thats why hydraulics get used, the cylinder can deal with a harsh environment in air or underwater and easy to custom design and make

Nice if we could do that with linear electric actuators easily...

 
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Zonker

Super Anarchist
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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.

Are you needing the high capacity load to drive the board up/down when loaded? That of course drives the loads up very high. The owners just want to push a button and the boards move, no matter what? 

On my 40' cat it was manual 2:1 - I lifted it up. Board was only about 100 lbs and buoyant so I just waited for the right moment as it unloaded off a wave and jerked it up a foot at a time. Not quite pushbutton sailing.

 

Kenny Dumas

Super Anarchist
1,651
12
Oregon
Interesting question Zonker:  I wonder if it would make sense to have some spring / stored energy you could apply that would do a similar function.  Put it under tension to lift a foot or whatever and let the natural wave loading move it when its easy.

 

Sailabout

Super Anarchist
soma said:
We tried to make hydraulics work. The difficulty was the 2.3m stroke and 9 tons pull, 2 tons push. At 1:1 it was a 5+m ram, so the buckling load was significant. At 1:2 our ram length got shorter, but 18 tons of load got tricky and we were still left with a 2.5m ram (which was hard to hide inside the boat). 3:1 and 4:1 got crazy with loads. Magic Trim etc couldn't get us there. One feature I really liked was to use the board's lift as recycled energy, ie like a canting mast. You could drive one board down with the lift from the other side. That way you could avoid HUGE power packs and the needed ampacity. In the end, though, there was a simplicity to a big electric winch that was hard to ignore. $2000 from Amazon Prime is nice, too.

I'm not convinced that this is the winning solution, this may be an area we revisit, but for now we have a plan.
yes long rams get ugly from an engineering perspective

 

Zonker

Super Anarchist
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Interesting question Zonker:  I wonder if it would make sense to have some spring / stored energy you could apply that would do a similar function.  Put it under tension to lift a foot or whatever and let the natural wave loading move it when its easy.
I know of some people who load the board uphaul on a winch and tension them. They "pop" the board up in exactly that way when they unload on a wave.

 




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