Full Pilot house on a GS28X or PG25C Panga?

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TomTom
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Re: Full Pilot house on a GS28X or PG25C Panga?

Post by TomTom »

Having re-read your initial requirements for power, I think that the GS 28 would fit the bill well and also surprise you with its efficiency. I suspect you would meet those cruise speeds with a single 150 HP so 200 would be fine.

I also agree with Matt that you could build a light enough structure and not affect performance too badly so long as you didn’t start using the cabin as a dumping ground for gadgets and fishing accessories!

And I also agree with your point that a superstructure with a tower etc vs a light cabin there is probably not that much difference.

I think you could balance the extra weight fwds by moving console area slightly back if needed - but I wouldn’t go with a bracket option.

barrelroll
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Re: Full Pilot house on a GS28X or PG25C Panga?

Post by barrelroll »

I've got a pilot house roughly mocked up on the GS. Frame spacing makes for a 6' long pilot house floor. The back of the pilot house falls where the back of the console is in the study plans. Drop the sole to the bottom of the stringers in the middle of the pilot house and the peak of the roof is roughly 32" above the gunnels with a 6' walking height. Instead of a large console just a small dash would bump out from the cuddy bulkhead, 2 seats on pedestals and everything modular/ removable. Around 6-7 sheets of foam with a lot of waste, large lexan windows for anything besides the windshields and 36" long marine sliders for the helm seats to drop weight even more.

How much weight if any does going with honeycomb floors/ soles save over the speced 1/2" plywood?

The plans call for 2" aluminum pipe for the tower, rough guess 150-200' of pipe @1.24 lbs per foot with weight up much higher. Dropping the sole to between the stringers helps get it a fair amount lower than the tower as well.

fallguy1000
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Re: Full Pilot house on a GS28X or PG25C Panga?

Post by fallguy1000 »

All about flex.

1/2" ply is okay on spans under 20", but needs topside laminate of about 1208 minimum for wear

1" honeycomb can span 50", but requires a mega glass layup for that., so its apples to donuts
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rick berrey
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Re: Full Pilot house on a GS28X or PG25C Panga?

Post by rick berrey »

If you do not plan on a foam build using infusion then I would consider that for weight savings over all . Replacing heaver layups of 1708 that are not in structural areas where mat is used only for puncture resistance with 1700 , and maybe Kevlar might save a pound here or there . I think Evan used some carbon fiber in his catamaran rebuild in non structural areas of the interior , he might advise on weight savings .

TomW1
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Re: Full Pilot house on a GS28X or PG25C Panga?

Post by TomW1 »

Jacques has pointed out time after time that building in foam for small boats or structurers do not save weight. The extra fiberglass and epoxy make up for the weight of the wood. Building the pilot house forward is definitely going to affect the LCG by a couple of 100lbs. So, he will also need to move the helm back 6"-1'. I would have to do the calculations to say how much exactly.

Barrelroll one thing you will want to do is install the skeg since you're in the Gulf of Alaska.

I am not sure why he wants the extended front end on his sketch but if he cut it off as it came down from the front that would be great, or even a couple of feet for a toilet. Maybe he can explain what it is going to be used for?

If he only wants to do the white section on his sketch, I think that would be fine.

Tom
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rick berrey
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Re: Full Pilot house on a GS28X or PG25C Panga?

Post by rick berrey »

If you go back and read past post on use of foam and weight savings on the forum , I think you will find around 25' is the rule of thumb where weight savings start . If foam would not give a weight savings to a narrow beam boat designed to be light like the GS28 , I don't think it would be a design option , but I'm not the designer . The Designer gives the options , if they were not safe or feasible he would not give them as options , so if someone ask if they can build in a pilot house , and it is listed as an option , the answer should be sure you can , and it is safe and feasible or the Designer would't have given you that option . Foam will save weight on larger boats if the work ( method and means ) is done correctly and as per design . Weight for E-glass is 159 lbs per cubic foot , Kevlar is 89.9 lbs , so about half the weight , carbon 108.9 , Kevlar cost factor will be around 4x E- glass , but if you can replace some epoxy sucking mat or E-glass with Kevlar or Carbon infused on foam then you have some major weight savings at a cost .

fallguy1000
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Re: Full Pilot house on a GS28X or PG25C Panga?

Post by fallguy1000 »

Any boat CAN be made lighter in foam. Fact.

Will it be as good as a ply boat? Maybe better, maybe worse.

I can't wait for winter to show you guys a short, ultralight foam boat.

The reason foam in almost ANY pilothouse is a good choice is that lower weights up high keep the boat more stable. And, fortunately, a great layup for foam pilothouses can be done with 12mm cores and db1700 glass each side. Using vac, you can reduce the weight by about one pound per yard if you want to work that hard.

But.

Many a pilothouse has been built in 6mm plywood with lighter skins. And the weight tradeoff is not great. I can calc it, but not now. Dinner bell..
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Matt Gent
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Re: Full Pilot house on a GS28X or PG25C Panga?

Post by Matt Gent »

The foam payoff comes at smaller structures when you don't need the skin thickness for puncture resistance.

fallguy1000
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Re: Full Pilot house on a GS28X or PG25C Panga?

Post by fallguy1000 »

Matt Gent wrote: Fri Sep 16, 2022 7:49 pm The foam payoff comes at smaller structures when you don't need the skin thickness for puncture resistance.
Bingo
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OneWayTraffic
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Re: Full Pilot house on a GS28X or PG25C Panga?

Post by OneWayTraffic »

Having another read of the OP and further information he provided I think that the PG25 should be given another look. The C and P series perform very close to the Tolman that he already has, and it seems like one main factor for the second build is to change things that he is not satisfied with for his first. Ride in a formed sea being one of the main reasons. I have the pilothouse console plans, and I am sure that they could be built very light, using foam or 6mm ply. The cuddy could be redone as a jump cabin with fishing platform on top, lowering windage somewhat. A fuel tank in the bottom of the boat would help a deal as well.

When it comes to ride in chop the PG25 is one of the best options out there.

There's a good discussion on this thread where TomTom and the designer have a chat about the two boats.

viewtopic.php?t=60954

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