GB5508 Rebuild - Soma's Project

Zonker

Super Anarchist
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Canada
Failure to comply with the established rules for thickness places you at risk of a rejected insurance claim should a window failure occur
Hmm, maybe in a rule bound country (Australia or Europe?) I'd be rather surprised if an insurance underwriter has a surveyor capable enough to even do the calculations...! Maybe for a big claim?  Does the ABS HSC rule even apply to sailboats? (Never checked actually). So much of the HSC rules require one to define the wave conditions and vessel speed in those conditions. But sometimes on offshore races you don't have the choice to seek shelter so how do you pick loads :)

Also, ABS Offshore Rule (now obsolete) gives very high pressure heads for deck structure. GL (Germanisher Lloyd) Yacht Rule gives much more realistic heads. Guess which one I used for designing the bridgedeck cabin for my catamaran? :)   Same story for windows I'm guessing. I didn't do the calcs...

 

Zonker

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That Servoprop could be an interesting asymmetric propulsion system.

Have a (bigger) diesel in one hull for open water propulsion. Have Oceanvolt in the other hull.

Use both to get off the dock.

Use the Oceanvolt to drive around a harbor for daysails, short term propulsion, and power generation in open water.

Nice light weight solution... but nobody likes asymmetry except the proa people!

 

Raz'r

Super Anarchist
62,385
5,538
De Nile
That Servoprop could be an interesting asymmetric propulsion system.

Have a (bigger) diesel in one hull for open water propulsion. Have Oceanvolt in the other hull.

Use both to get off the dock.

Use the Oceanvolt to drive around a harbor for daysails, short term propulsion, and power generation in open water.

Nice light weight solution... but nobody likes asymmetry except the proa people!
hmm, 2 OceanVolts/Servoprops, Li battery bank in one hull, diesel generator in the other?

 

Zonker

Super Anarchist
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Canada
So if the battery bank is near dead - you only have < 6 kW / side for propulsion. Assuming 95% efficiency (and that is being really generous - line losses, VFD losses, electric propulsion motor losses). That's 7.5 HP / side.

I guess the generators auto-start so that the bank is never depleted too much. But even still, imagine if  you're trying to motor into 40 knots of wind in a narrow body of water. I think you'd go backwards... 

 

Geese

Member
I know very little about this, except to say that  the power cat used to get out to buck island in STX built by Gold Coast can get a huge payload up on a plane with the generator running and then go at trawling speeds quietly on electric only in and out of harbor. I imagine he battery bank is much larger than on a sailing cat.

 

Solarbri

Member
364
67
Wyoming
So if the battery bank is near dead - you only have < 6 kW / side for propulsion. Assuming 95% efficiency (and that is being really generous - line losses, VFD losses, electric propulsion motor losses). That's 7.5 HP / side.

I guess the generators auto-start so that the bank is never depleted too much. But even still, imagine if  you're trying to motor into 40 knots of wind in a narrow body of water. I think you'd go backwards... 
I think I’d choose to go backwards...   

just sayin’ :ph34r:

 

mrybas

Member
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85
soma said:
-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. 
Have you decided on Maui Jim's or 7-11 shades?

I'm going to have to make the same decision soon for a cat I'm refitting.  I've flip flopped back and forth about a half dozen times in the glass vs acrylic debate.  Now I'm thinking about glass in the openings that get used while navigating for optical clarity and scratch resistance. I'll use a transparent window film that cuts down on solar heating of the cabin.  The other windows I'll use acrylic to save weight.

 

Boink

Super Anarchist
1,589
779
Nice one Soma - can you reveal the expected overall gross mass for the boat in sailing trim? 

Can you spare the time to describe the foil skimming methodology? 2/3 or even 4 legged and the load proportions that each foil will carry?

 

HotCarNut

Member
57
16
Denver, CO
soma said:
Project is going well. The interior has been fully painted. Systems are going in, electricians got started this week, generators are going in this week as well.  

-Hybrid drive system starts to go in next week.

-Exterior paint has begun, we plan to shoot the deck gloss and coachroof this week.

-Rudder design has been finalized.

-We weighed last week and we are still on track. The trend line is going down...not into the 9.something area...more like 10.4t. That's about 4 tons lighter than a standard 55. 

May isn't going to happen, likely in the water in June, certainly by July. Luckily we don't have a deadline...

As for skimming, we have targeted 8 tons of vertical lift on the leeward daggerboard at 25 knots of boatspeed (at stall). The T rudders will be set to a 0 degree AOA, and the windward board will normally be up and set to -2 degree AOA. With that said, there will be lots of playing with different modes. We have a +/-2 degree AOA on the rudder and +5/-2 degree AOA on the daggerboard T. Maybe there's a deep downwind mode with both boards half down and raked aft. Or maybe we can cheat an early upwind hull fly with max AOA on the windward board, and negative AOA on the leeward. It'll be fun to experiment. I fully expect windward heel at times, and probably flying the leeward hull, too. 
Given that weight savings, are you pretty optimistic about the performance targets you were hoping to achieve?  I know the original 55s handled like pigs, causing the quick re-do into the 57s.  You've taken a completely different approach, and it's REALLY interesting.  Makes me wonder what the other hulls might turn into....

 

mpenman

Member
251
234
Pompano Beach
soma said:
I'll just go ahead and say it...gulp...if 5508 isn't the fastest Gunboat I'll have failed. 
4 tons is a fair bit of weight savings. It's interesting to note that it's 'better' to use an existing hull and rework than start from scratch.

In your humble opinion, who are the best multihull builders in the world currently?

 

yl75

Super Anarchist
3,139
1,541
France
soma said:
Two servo props, two battery banks, two 6kw generators. There is an opportunity to criss-cross if needed. 
Interesting, what led to the decision to go for two generators instead of one ? Failure redundancy ? Weight deistribution ? (as I assume that regarding kW per Kg, two is less efficient)

How many kWh in the battery banks ?

And do you have an estimation of the speed you will get on generators power in a dead calm situation ?

 
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F18 Sailor

Super Anarchist
2,675
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Annapolis, MD
Very nice Soma. The other side is everyone is talking environmentally friendly, when this is probably the best eco-friendly approach, i.e saving 2.5 tons of resin from a landfill somewhere. Hopefully the other hulls found owners with similar ambitions?

I too am blown away by what Marsaudon offer. Paradox and Idec are phenomenal boats and bring that level of craftsmanship to a cruiser/racer at their price points is truly impressive.

 

HotCarNut

Member
57
16
Denver, CO
soma said:
Long story short, they laid up the dry stack (carbon/foam/carbon) for 5514 in the tooling, but couldn't infuse because the resin that they had left was expired and they couldn't afford more. So they left the drystack in the tooling for weeks/months, uncovered. Then, apparently, some disgruntled employee took his rage out on the drystack and ripped it all down. They put it back up in place the best they could. Then, apparently PJ was getting really short on cash, so he instructed the workers to infuse the hull with expired resin, presumably to trigger a progress payment. 

I've heard this story from enough people that I accept it as true. To put it another way, we felt that this information was "true" enough that I wouldn't sell it when I worked at Gunboat.

To clarify, the hull in question is 5514. There is no 5511, 5512, or 5513. I guess the buyers of 11 and 12 knew it'd be cheaper to walk away from their deposit than to move ahead, so those projects never began. Presumably, you skip hull 13 because it's 13. 

5514 was the last boat infused. Last I saw it was still in the tooling.
I meant to ask, are 5509 and 5510 being completed as well?

 

HotCarNut

Member
57
16
Denver, CO
soma said:
The hull itself is pretty heavy. You'd definitely do better weight-wise starting from scratch, but we picked up 5 tons of carbon, foam, and resin fully assembled for $0.10 on the $1. So that IS better. Starting from scratch (in the US) would have cost an extra $1m - $1.5m (and probably could've saved 1 ton)

The obvious names, CDK, Multiplast, Persico, McConaghy. I'm absolutely blown away by the value that Marsaudon offer. They built Idec, Paradox, etc, but they also build the TS boats at a fraction of the cost of the competition. 
Interesting....I note that neither Gunboat nor the current owners are on this list.  Pretty telling....

I was hoping the move from Nigel Irons designs to a VPLP design, coupled with the expertise in France, might vault Gunboat back to the top.  What is the weight like on the new 68? Haven’t seen anything published yet on where Condor ended up after everything was loaded in.

 
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yl75

Super Anarchist
3,139
1,541
France
And have you decided on the solar arrays/cells that you will use yet ?

I've seen that Moonwave have used http://www.gochermann.com/

But looking a bit around on the web (there is not much) , these seems very expensive, making only custom arrays, used a lot for "solar cars competitions",  and it is a tiny company right ?

What about Sunbeam systems ? http://www.sunbeamsystem.com/us/

Solbian ? Others ?

 
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