CDX plywood as top rail?

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matt167
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CDX plywood as top rail?

Postby matt167 » Sat Jul 06, 2013 7:18 pm

I've got a few things to finish up with my 8' drift pram before it's done. I know it says to basically use a few sticks of wood for the top rail and seat box support as per the plans, but I have not been able to find DF in anything less than a 4x4 post local. Not sure why. Also the cost to get the local saw mill to cut down a 4x4 for me is outrageous... I bought 4 sheets of 5/8" CDX plywood from the local lumbar yard a while ago and it's no longer needed and not returnable but has been covered and on saw horses.. Can I cut the CDX into strips 2-3" wide or so down the side, and then laminate the top rail with the CDX with PL-400 adhesive and monel nails. Like two strips on the outside, and one on the inside? and then fiberglass over it with some cloth? Also want to back the transom with CDX so that it can use an 18-20# thrust trolling motor if I ever put the boat on a larger body of water.

fredt
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Re: CDX plywood as top rail?

Postby fredt » Sun Jul 07, 2013 4:28 am

You may find those that say it will be fine. IMHO cdx being a construction grade plywood will be very
suspect to delamination, it has voids in the plys, and I think there is only 4 plys in 5/8" , which is actually
not quite that thick.

Although it is used as substrates under roofing , and header scabs , etc,. with the time you will be
spending encapsulating it, you may be better off just buying something a little better if you can.

matt167
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Re: CDX plywood as top rail?

Postby matt167 » Sun Jul 07, 2013 12:28 pm

whichever way I go, it will be wrapped in fiberglass. I did manage to find a supplier of 8' sticks of 1"x2" DF softboard for $12/ stick.

matt167
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Re: CDX plywood as top rail?

Postby matt167 » Tue Jul 09, 2013 11:02 am

Well, this is back to the drawing board. I didn't follow the directions entirely ( misread them ) and didn't install the seat facings before putting the sides on so now the geometry is all wrong up the side of the boat. I thought that I could just cut the facings in 1/2 and then trace and 'adjust' them and glue them back togther but it's all flubbed up.. I'm going to template new facings out of cardboard and build them out of 1x10". Think I'm just going to use cheap pine boards because it's inside and it will all get 'glassed and painted anyway.

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Bill CNC
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Re: CDX plywood as top rail?

Postby Bill CNC » Tue Jul 09, 2013 3:03 pm

Crappy wood weighs more by the time you get it to a finished state. First you'll have to fill all the outside surfaces BEFORE you glass it. Also, the shoddy wood in CDX is a little more porous causing more resin to be used all costing in money and weight. You will spend more money and time trying to finish a crappy piece than you would if you had used quality wood to begin with.

I for one am puzzled by those that chose to make their own boats from shoddy materials. After all the time spent on building it and trying to make it look nice, ... only to stand back and think, ... money tossed down the drain. I understand the money thing, ... but you don't have a deadline so save for the good stuff. Might be why they say a boat Boat $30,000, ... it's just $30.00 at a time.

The motto should be, ... Work SMARTER, ... not HARDER!

Bill
Bill

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matt167
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Re: CDX plywood as top rail?

Postby matt167 » Tue Jul 09, 2013 4:48 pm

I used marine grade Douglas fir plywood for the hull and original seat facings. I'm not going to use the CDX. Instead, I will use 1x10's in either Doug Fir if I can find some or Radattia ( misspelled ) pine if I can't. Weights should be simmilar. It shouldn't end up much heavier than the original design, as that called for Douglas fir 'sticks' to support the plywood from the inside, and on the top rail. It's just replacing the plywood with 3/4" material and omitting the extra support as it would be unneeded. We don't have great selections of marine woods here. Almost everything needs special ordered which also carries a delivery charge.. On an 8' dinghy, I just don't see spending a ton.

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Bill CNC
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Re: CDX plywood as top rail?

Postby Bill CNC » Tue Jul 09, 2013 5:14 pm

The CDX is were things get heavy trying to make it look nice and smooth. Since you didn't use it, ... I guess there isn't an issue. :wink:

The point I was making is that your wood selection is just as important as your engine or hardware. Sure, probably any wood would work, but some wont pass the test of time, very short time to be exact. I have seen people make things on a budget, that in the ended costing more than if they would have NOT tried to skate by on a nickle budget. When you spend the time and money to buy the plans, wood, hardware, engine and paint and all the other do-dads, ... and then do what I call a shake and bake build, ... (toss in wood, glue and nails and paint in a bag and shake it for assembly) You would have been better off, just sitting on the bank with fishing pole in hand, and watch all the pretty boats go by.

Row boat or not, ... it's your blood, sweat and tears. When someone looks at it, ... do you want it to look like you busted your hump for 5 minutes, or 5 months? In my opinion, ... Every job should have the same dedication to it whether your making an ore, or a 30' master piece, ... but that me.

Bill
Bill

TNT Build, ... On Going, ... http://tinyurl.com/abmae64

The Freebie Zip, ... On Going, ...http://tinyurl.com/at3udss

Super Spartan Build "Miss Tripindicular", ... Completed, ...http://tinyurl.com/b488wsz

matt167
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Re: CDX plywood as top rail?

Postby matt167 » Tue Jul 09, 2013 5:33 pm

I understand. I do plan on finishing it right and making it last. I just might have a supplier problem getting the wood I need. I think I will be able to find 1" stock Douglas fir somewhere tho.. It'll all work out.

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thudpucker
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Re: CDX plywood as top rail?

Postby thudpucker » Thu Jul 11, 2013 11:09 pm

Think of it this way. The Stuff you use will probably out last your use of that boat! :lol:

You put what you want in it and on it.
Next boat you build, you'll know more and it still wont be the last boat you'll build! :lol:


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