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sealing frames / marine plywood


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  #1 pakalolo

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Posted 07 August 2012 - 07:51 AM

Sorry if this has been asked. I try to search a bit before posting, but I didn't find my answer.

Are any of you sealing your marine plywood frames with anything? It just seems weird to me to have exposed, but maybe I missed something in the book or on the forums.

A month ago I was helping to put a new deck on a sailboat restoration. We used marine plywood and coated the underside with west expoxy.

Does anyone do anything to coat their frames or are they fine just being how they are?

Thanks!

  #2 Kudzu

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Posted 07 August 2012 - 08:25 AM

Unlike a big boat, your bkayak should not be constantly exposed to water and moisture. You paddle it and then store it out of the weather where it dries and stays dry. Nothing like leaving one sitting on the water 24/7. With good plywood, oil has proven to work just fine.
Jeff
Kudzu Craft SOF kayaks
www.kudzucraft.com

  #3 P Douglass (WA)

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Posted 07 August 2012 - 09:10 AM

I covered mine with boiled lenseed, a couple liberal coats after it was all lashed together. Next one I well be tempted to cover the top of the floorboards with ZAR varnish just to make it easier to clean/get rid of footprints.
P Douglass
1st build - Curlew

  #4 Kudzu

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Posted 07 August 2012 - 10:26 AM

Good point Paul. I usually paint mine just for looks.
Jeff
Kudzu Craft SOF kayaks
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  #5 FloatingBear

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Posted 27 September 2012 - 11:13 AM

Hello guys. I am building a Pirogue with hardwood plywood per Uncle Johns Plans and the suggested epoxy from RAKA in Florida is quite thin when mixed and penetrates wood well if you want something that will completely seal your frames. By using this product you will have a boat that is slightly heavier by I will guess 3 or 4 pounds but it would be sealed and insainly strong.

  #6 DURRETTD

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Posted 28 September 2012 - 10:41 AM

I agree with FloatingBear. Epoxy is messy and expensive, but it seals the plywood. I coated my plywood frames and my stringers with epoxy, then epoxied and screwed the stringers to the frames. The frame is very stiff, which may or may not be a good thing; I prefer the stiff frame and decided to go with epoxy and screws largely for that reason.

I also used 3/4 inch ply for my frames to reduce the chance of splitting. The epoxy and the thicker ply certainly added to the weight, but after lifting a polyethylene boat for 25 years, my over-built skin-on-frame feels light.

Dan

  #7 P Douglass (WA)

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Posted 28 September 2012 - 10:55 AM

The Eskimos didn't have all this stuff! :) Coarse they didn't have polyester either..
P Douglass
1st build - Curlew

  #8 Kudzu

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Posted 28 September 2012 - 10:57 AM

LOL Paul. I used to say Overkill was good, till I started building lightweight boats. Now it is just a waste.
Jeff
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  #9 woodman

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Posted 28 September 2012 - 12:45 PM

I tell you what.....on the full kayak frames (not the canoe frames) 3/8 Baltic Birch is plenty tuff...you guys ought to try it ..it's a lot lighter...I've used it on 3 out of 6 skin boats.... :) so-far.....

  #10 Kudzu

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Posted 28 September 2012 - 12:58 PM

I tell you what.....on the full kayak frames (not the canoe frames) 3/8 Baltic Birch is plenty tuff...


That is on my list to try. I forgot last trip to Chattanooga to pick up a sheet with the rest of mine. I want to build a Baidarka this winter and will probably try 3/8. I only have 1 full sheet so I have to drive up soon and get some.

I want to try it and beat the boat around before I recommend it. But I suspect it would work in most cases.
Jeff
Kudzu Craft SOF kayaks
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  #11 FloatingBear

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Posted 30 September 2012 - 04:31 AM

Mr Woodman what did you use on your pirogue and canoes for frames?

  #12 woodman

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Posted 30 September 2012 - 05:32 AM

Mr Woodman what did you use on your pirogue and canoes for frames?


I use the 1/2'' Baltic Birch for those......
I still have a uncoated test pc. of 1/2'' screwed to a fence post that has no sign of delaminating after a few yrs. now...

  #13 Kudzu

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Posted 30 September 2012 - 01:24 PM

Baltic birch is WONDERFUL STUFF! The more I use it more I LOVE I, not like it.

I noticed a weak spot developing in one of the Douglas Fir plywood frames in my Long Shot last night. This is the second frame I have seen weaken and start to loose loose strength. The more I see of Douglas Fir the less I tend to recommend it. I think Baltic Birch is a superior product. The only thing it doesn't do well is pass the boiling test, but epoxy fails that one too and I don't tend to boil my boats any. :-)

I am thinking about pulling out that frame and putting a new one made of BB.
Jeff
Kudzu Craft SOF kayaks
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  #14 P Douglass (WA)

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Posted 30 September 2012 - 03:08 PM

Got to be sure everyone understands you are talking the 5'x5' sheets of Russian(?) Baltic Birch and not the 4'x8' stuff purchased at the big box stores. Some new builder here may not realize there is a difference. I didn't until I can here and did some reading. Is it called Russian Baltic Birch or did I dream that at some time?
P Douglass
1st build - Curlew

  #15 Kudzu

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Posted 01 October 2012 - 05:01 AM

Your right. Baltic Birch is only made is Russia, birch plywood is not the same stuff.
Jeff
Kudzu Craft SOF kayaks
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  #16 FloatingBear

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Posted 01 October 2012 - 10:53 AM

OK Here is the stupid question. What are some of the better options for someone who does not have access to Baltic Birch???

  #17 P Douglass (WA)

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Posted 01 October 2012 - 12:06 PM

You could use Okoume plywood, Meranti plywood, Douglas Fir plywood, but any place you have about that would sell these would sell or be able to get you Russian Birch, I would think. Not know where you are located or what you have available makes it harder to answer. Remember you don't need but one sheet so it's not going to add up to a whole lot. I drove 130+ miles one way to get Russian Birch. My mistake was I figured I'd better buy 2 sheets in case I make a big mistake. I didn't even use a whole 5' x 5' sheet so now I have to build another boat to use it all up.
P Douglass
1st build - Curlew

  #18 Hirilonde

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Posted 01 October 2012 - 02:06 PM

The primary characteristic of the Baltic Birch that makes it so strong, even when cut into kayak frames, and delam resistant is very thin, continuous and well glued laminations. No American made plywood has such thin (therefore numerous) or integral layers. The only plywood that competes in this regard is BS 1088 marine which comes in Okoume, Meranti and Sapele. These 3 are actually superior, but also even harder for most to find and more expensive. Marine versions of Fir plywood have no more layers, or better layers than construction grades of plywood. This is why even though they supposedly stand up to the marine environment they are terrible structurally.

edit: FloatingBear, try a cabinet shop, or custom woodworking shop. They might be willing to sell you a piece. Probably a little expensive, but if no other source it may still be worth it. Based on the kayaks I have built I can't imagine even Jeff's largest kayaks require more than a 3'x5' piece.

Dave Finnegan

1967 Pearson Renegade  "Hirilondë"

Spindrift 9N #521 -  many KudzuCraft SoF kayaks


  #19 Kudzu

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Posted 02 October 2012 - 05:06 AM

What are some of the better options for someone who does not have access to Baltic Birch???


The best answer is dig in and find Baltic Birch. You will not find in most normal places. Get on the internet and local yellow pages and find the suppliers that sell to the wood working and cabinet shops. The wholesalers, but everyone I have dealt with would sell to anyone. Just walk in and tell they want you want. There is the idea that you have to be a business to buy, but I have never had any problem buying at a distributor.

In my new book I stress how hard it is find good plywood and that your hardest task in building a new boat will likely be finding the plywood. It's out there but it will just take making a few phone calls to find it.
Jeff
Kudzu Craft SOF kayaks
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  #20 Kudzu

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Posted 02 October 2012 - 05:30 AM

Based on the kayaks I have built I can't imagine even Jeff's largest kayaks require more than a 3'x5' piece.


If your going to cut out the 3 piece coaming it takes a 5x5 sheet. There will won't be much useful scrap left
Jeff
Kudzu Craft SOF kayaks
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