Flat Panel Construction

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fallguy1000
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Re: Flat Panel Construction

Post by fallguy1000 » Wed Mar 08, 2017 10:02 pm

jacquesmm wrote:
Fri Feb 24, 2017 11:07 am
Correct. It is a method we use on the foam sandwich versions of some of my designs.
For a 32' cat with almost flat panels, you should not have any problems.
Derek Kelsall does that for many designs.
Do not try without the single skin: the panels would sag between the molds.

What we do is layup one layer of glass on the outside and when assembled, add the specified layers up to the final lamination schedule. It allows you overlap the layers over the other panels and create string seams that way.

I have files and notes about and plan to publish later this year.
Jacques, Why would the panels sag between the molds on a full male mold with stringers? I want to use corecell and I could shoot a few raptors into the core on stringers to hold the shape. Then, I could also shoot a few raptors into the fabric if you think it'd move on me after wetting out. The boat is designed with female mold; to do flat panel would require more work than building a skeleton I think.

Do you foresee any problems? I would use peelply.


My boat build is here -------->

viewtopic.php?f=12&t=62495

fallguy1000
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Re: Flat Panel Construction

Post by fallguy1000 » Mon Apr 10, 2017 3:40 pm

I posted my plans on another forum and I was told the boat would be rather floppy and hard to maintain its shape coming off the male mold.

So, I was advised to build full female mold by one fellow who said I could put all the bulkheads in the boat and the boat would be real stable and not lose its shape.

Doing it that way, I could even build the deck and tape it in and glass it over the top, remove half of the mold and glass the first couple feet of the hull and leave the peelply on before flipping and then finally glassing the bottom.

It is a change from what I proposed earlier to Richard, but hopefully he'll agree this way would be better for the boat to maintain its integrity after a flip.

I don't believe it would be wise to do any of the exterior glasswork in advance of glassing the inside.
My boat build is here -------->

viewtopic.php?f=12&t=62495

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Re: Flat Panel Construction

Post by jacquesmm » Mon Apr 10, 2017 4:10 pm

Building foam sandwich one-off boats on a male slat mold or on a male mold with pre-skinned panels is done by hundreds of professionals since 50 years.
See pictures here:
http://bateau2.com/howto/foam1.php

I built many boats that way and crossed the Atlantic several times on one of my boats.
The panels will not sag if you use a slat mold. The panels will not sag if they are pre-skinned.

There is a valid way to build foam sandwich in a female mold: tight set of stations and foam strip planks. I find it complicated but useful for round chine hulls.
That method is used by Ian Farrier.
He also shows another method that uses foam panels about 4' wide and screwed with buttons to a female slat mold then fiberglassed one panel at a time.
I find that very complicated and risky. It is easier to do the same thing on a male mold with a cleaner result.
What is easier to fair? A male shape or a female one?

That is my opinion based on many large boats built in foam sandwich but this is not my design, I will let Richard give his opinion.
Jacques Mertens - Designer
http://bateau.com

fallguy1000
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Re: Flat Panel Construction

Post by fallguy1000 » Mon Apr 10, 2017 8:48 pm

Thanks Jacques. Richard is busy right now, so I need to give him a week or two to answer.

The concern expressed by others was that the male hull would be too floppy when removed from the mold and so I would not be able to remove it from the mold until the flip was done (mold and all). The other guys said they thought by putting the bhs and compartments, bases in, and the deck, the hull would have much more integrity for the flip. I have no experience with this part myself, except for a canoe build where the inside of the hull was done post flip and I remember how floppy the 16' boat was then. This boat is 32' long and far, far more area.

They have a point. But then I realized there are more hours involved in the male method.

For example, all the panels need to be prefit to the male mold, then removed and glassed on the inside skin. In the female method, once the panels are placed onto the mold; they stay there until glassed. I can even put rebates into the female side for tape joints and result in less fairing for the areas that are visible inside, not so if I preglass on a table.

Then for removal, I was considering removing only a section of the male molds at a time by using a cleating method. The cleating method also would not be needed. And if I split the female mold at the first or second flat portion of the hull(it must be split for the reverse chine at the deck, so I could split it a little further down below the deck chine/gunnel), the deck could be fitted and faired while the hull sits in the mold. The only part of the boat that wouldn't be glassed on removal from the mold would be the lower chine(s) and bottom. Then on removal, the mold never leaves the floor and it is ready for the next hull once the top section of the mold is replaced.

The only downside is all the in and out, but I'm only 50 years old and still somewhat agile and I have enough head clearance to do it. The male method is more familiar to me as a canoe builder, but I see big upside this other way.

btw, I plan to purchase 75 gallons Silvertip from bateau for the build I am ordering supplies in June.. I already ordered the crossbeams for the boat.
My boat build is here -------->

viewtopic.php?f=12&t=62495

fallguy1000
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Re: Flat Panel Construction

Post by fallguy1000 » Mon Apr 10, 2017 8:53 pm

If you were going to build the female full mold method, would you keep the transom off the boat and use it for a work entrance (working from stem to stern so to speak) and peelply to the transom for the last thing before deckwork, or would you just build and glass the main hull and then walk up and down into all the time?
My boat build is here -------->

viewtopic.php?f=12&t=62495

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