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Foam Core Princess


Brent

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I have a Princess 26 under construction. This boat is being built using vacuum bagged laminated foam core construction. This construction is more difficult than wood, but should be very strong and light weight.

First I had to build a vacuum pump rig.

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Then the laminating tables

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Then source the materials

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Here are some of the first laminations. Vacuum bagging has its challenges, but gives very nice results.

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Now the hull is assembled, trued, and the hull bottom panels are going in.

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Brent

Congrats & thanks for the great pics. Well I would award you at least Three Gold Stars - for bravery!

Now that you've opened the topic you need to be prepared for lots of questions

I for one would like to learn the difference between the specs for the as designed plywood panels and the foam cored panels -- including the weight/squarefoot for each

How are you doing hitting the expected panel weights?

Keep the pics coming love to see the intimate details.

Great stuff,

TomH

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Brent:

You are ahead of me. I've begun marking out the stem, stem cap and stem knee and am still shopping for the structural wood. Was concerned about what to do with a pallet of plywood, but found out my cousin has a forklift, so now have that covered. Have also overcome my Dad's objections to using his wood working shop, but will have to clean it out first. Not a trivial thing.

Have studied the P26 plans (a lot) and the photographs of your boat going together, and notice a few things that look different. Would like to visit with you about these. I'm going to stick with the plywood version, as per the plans, but there should be a number of similarities to compare notes.

Send me a PM or email and maybe we can trade phone numbers.

Howard

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Howard, Yes there are a few differences from the plans. Some of these are due to differences in laminated foam core construction versus plywood and some are simply my choice.

Oyster, Good to hear from you my old friend. I thought hard about hiring at least portions of this out, recognizing this is a huge project. In the end I am taking it on myself,but will certainly be tapping into my network for help with certain parts. That is my backyard, my garage, and a familiar cat (which I wont claim as mine). I am hoping to get the hull to a stable condition before winter sets in and weather will certainly be a factor in the schedule. Wish I had a nice place to work like yours. Also wish I had your skills, but I will just have to cope as best as I can.

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Looks great Brent, glad to see another builder taking on an endless project :) . I'll be watching with great interest, especially the foam core process. She should move nicely in lite airs.

I almost bought the 26 plans when I built my Belhaven. If I would have I probably wouldn't be building my 28.

Good luck and please keep us posted.

Scott

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For Tom and 176 The hull sides are half inch foam, and the bottom is 3/4. The 3/4 significantly exceeds minimum standards, but I wanted a stiff hull. There are two layers of 1708 on the outside and one layer on the inside. I am getting good quality laminations with about 1.0 lb of resin per lb of glass. If I am careful the net might be 20 percent lighter than a plywood hull of similar strength.

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http://www.amateurboatbuilding.com/articles/howto/foam_sandwich/index.html

Good article on this.

http://www.amateurboatbuilding.com/articles/howto/foam_sandwich/inside_structure.html

building the table.

I watched a guy build a 42ft cat over a couple years using a pre laminated panels he bought that had a simple overlap to easily lock together with epoxy... Not sure what the cost was but the finished project was great.

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Well thats quite an undertaking. I hope you enjoy it and make quick work of it and get it in the water for next season. [snicker, snicker] HEHE

Ms. Pearl and I went out after work and did what we enjoy on a nice early fall afternoon for about an hour and a half. The evening sun over the water was a nice treat after the summer's heat.. We were talking about you and your project while doing our part to uphold your end of the rod too. <_<

Big blues this time of year and quite an arm full in 8 pound tackle and speckled trout are beginning to show up.. Shoot an email from time to time and hope the family is doing well too.

.

Posted Image

Now back to your regular programming,

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For Tom and 176 The hull sides are half inch foam, and the bottom is 3/4. The 3/4 significantly exceeds minimum standards, but I wanted a stiff hull. There are two layers of 1708 on the outside and one layer on the inside. I am getting good quality laminations with about 1.0 lb of resin per lb of glass. If I am careful the net might be 20 percent lighter than a plywood hull of similar strength.

Brent

Thanks for the extra detail.

That 20% weight saving is a big number! Good going on that for sure. No arguements with a 1:1 glass/epoxy ratio.

What density foam is that being used? Brand? Type?

On the plywood version, what are the plywood thicknesses specified for sides and bottom?

On the forward part of the bottom...are those 'diagonal' planks pre-glasssed the same as the flat panels and then being taped together -- or are they being glassed after fitted, joined, and faired?

Your panels look really nice, btw.

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The plywood version specifies 5/8" for the bottom panels; 1/2" for the topsides and transom and 3/8" for all bulkheads, interior dividers and cabin sides. I didn't think material weight to be that much of an issue, so I am planning to use Meranti for all but the coach roof and sides, which will be Okoume. I think there are something like 40 sheets of various sizes of plywood on my order form, but surprisingly, the total, with shipping, comes to something around $3,500 for all of it. I had expected it to be more.

Once upon a time I had thought about doing some vacuum bagging of the side and bottom panels (vs. scarfing or butt joints), but I was thinking of laminating up long sections of topsides and bottoms from thinner plywood panels. Brent has taken this to a whole new level. They do look nice.

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Howard et al,

Not intending to hijack this post, I tried to send Howard a PM but it wouldn't send.

Howard, where did you end up getting your marine plywood from?

I need 24 sheets various sizes to build the PAR design Rocky, looks like I'm into it for $2500 or better from any Canadian suppiers. If the price was better I could ship to Grand Forks ND and pick it up there, it's only an hour and a half away if the price was right.

Thanks,

Ken

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Best price I found was from these guys:

http://marine-plywood.us/

To get a final price, fill out the order form to the point of buying, but do not buy. It will show the price, with shipping and discounts. If you don't buy, you may get an email from them to discuss options on shipping.

I probably checked 5 or 6 other online shippers and they always had the best price. I don't have a local source of marine plywood, except for fir, and it is sky high expensive here.

They also assure me they only sell quality plywoods and not the inferior chinese stuff. I don't have the shop ready, so have not placed my order, so can't confirm what they say about quality is true. Maybe someone else has used them and can verify?

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  • 1 month later...
  • 3 weeks later...

The hull exterior is now complete and primed. I wanted the primer on this fall to protected from UV over the winter, even though the boat will ride out the winter under a tarp. The primer does a good job of pointing out a few places that will get further fairing before final paint.

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Over the winter vacuum bag laminations will proceed using the sun room. It is a little bit warmer than outside.

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These panels are the cockpit sides. The whole cockpit is being assembled as a module to drop into the hull in the spring. Once the cockpit sides are cured, they will be connected to bulkheads 4 and 5, which are now removed from the hull. Then seats and cockpit sole will be added.

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I understand most of your boat is composite material, but you mentioned a tarp cover over the winter. In my long experience a standard "blue tarp" is evil. They trap moisture and will rust out a car or motorcycle inj one winter. A blue tarp will also create an ideal environment to rot wood and grow mold. True canvas tarps are way better. A "tented" blue trap isn't as bad as direct contact draped blue tarp, but I even avoid that trick now. I see a building nearby in one pic - a shed roof lean-to would do fine.

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