Gotta question from a nooby builder

[Lazyriverguy]

Hi Guys
My question is this and I asked it on Matt's site tooo. I went to the store to puchase my plywood fer my new P-Row TV and they did not have the marine ply that is suggested by Matt. So I had 2 choices to pick from. 3mm or 5.2mm. Now those who have been on the river with me know I ain't real easy with my boats so I goes fer the 5.2 birch by the way it is cabinet grade. Real purty. Now I need to ask is this thicker ply gonna cause me headackes or will it just be slighly heavier. A litte extra weight I can deal with. My thought was to not put so much epoxy/fiberglass in the inside of the boat yet well protected on the out side. Any thoughts. Please keep in mind this is my first build and all I been doing is readin from you fellas.
Joe

 

[oldsparkey]

Joe..

For you and your use I would suggest the thicker plywood. The Freedom is from 1/8th inch and glassed. Did that for the lighter weight but it does not take a cooler and all the heavy stuff that you put in a canoe.

The thicker plywood would serve you better and when the boat is completed it will be lighter then those metal ones you toss around. Several reasons for that , it is narrower then the Grumman's , lower but the same length. The wood weighs less , even when glassed on the outside and the inside if you plan on glassing the inside. The outside needs the glass since that is where most of the wear and tear happens to a boat.

Glassing the inside would be nice but if you did not want to then a good epoxy saturation to the inside to waterproof the wood. Plus you could glass the cockpit area since that gets the wear and tear from the person getting in and out all the time.

Yep... With all the stuff you take , the thicker wood. It is easier to work with and since this is your 1st build , take the easy route.

Chuck.

 

[hairymick]

G'day Joe,

All that Chuck said mate. go with the thicker ply. It will not only be stronger, It will also be way easier to work with.

My touring pirogue was made with 4mm exterior hardwood bracing ply that was heavier and 6mm luann per sheet.

The build was by far, easier than any other boat I have built and at the end of the day, the boat was still lighter than any comparable fibreglass or plastic job. 3mm ply is a PITA to work with by comparison.

 

[tx river rat]

Joe
I agree on the ply thickness I will never use 3 m again .
Mick will tell you that the cloth inside will work to your advantage, a rock got the bottom of one of his Lakers and the inside cloth held to where he could get home ok.
Do any of ya'll know where the thread about building a boat inside out is located.
Ron

( Ron .. Chuck here.. Inside out boat building , explanation please , then I might know where to look. )

 

[Lazyriverguy]

Thanx fells I knew if I asked I would get a good answer. Mostly cause you guys is my heros. And cause ya just gotta. I plan on puttin glass inside along with outside so I don't mess the boat up too much. As Chuck knows I do carry some stuff when I go. I just feel good about this thing I think it will work great. As I get to work on it I will start a build fer dumbies thread.
If ever there was one I is it.
Thanks guys.
Joe

 

[tx river rat]

I found it Joe

It is long but will give you something to think about.

http://www.neilbank.com/phpBB2/viewtopi ... highlight=

I think we need to make this a sticky Chuck

 

[Lazyriverguy]

Mr Ron Thank you that post was very enlightening. It does seem to point out that inside strenght is important and that outside scuffablity is needed. I was thinking the other way around. It does give me food for thought and the correct I think information to continue reading up on the glass or other cloths. Good stuff. Thanx again. I did make some marks on my wood last night so it is moving along.
Joe

 

[aub77]

The most important thing to look for in choosing plywood: exterior (waterproof) glue. NOT water resistant; NOT interior grade.

 

[gbinga]

The most important thing to look for in choosing plywood: exterior (waterproof) glue. NOT water resistant; NOT interior grade.

I've tried to make sure that the plywood in my boats was exterior grade (two with ultracheap very heavy BC pine, and most recently Ultraply XL premium underlayment - confirmed exterior glue according to manufacturor). I've always figured that a boat might get wet even if it is fully fiberglassed.

This brings up a question. Some feel that the wood is relatively unimportant (assuming that it is physically sound with decent surface quality and not many voids), as the entire boat is going to be encapsulated in epoxy and glass. Many feel that plywood should have exterior glue, in case it gets wet.

Does it matter, or not?

And if it does matter - if we think that cracks and pinholes might let it a little water - is it wise to epoxy the boat inside and out? If a crack or pinhole developed and the wood got wet in use, then it might take forever for it to dry out again (soaking up water through a pinhole will happen a lot quicker than said water drying back out by way of a pinhole).

If that can't happen due to the encapsulation and saturation, then why does everyone (including me) think that exterior grade plywood is important?

For instance, Lazyriver picked cabinet grade birch, which is probably a beautifull piece of plywood that will look great on a boat, but I wonder if it has exterior grade glue, since it is not an exterior product - at least cabinet grade ply that I have seen is usually not exterior grade.

So does it matter?

Regarding encapsulation, I decided to oil finish the inside of my Pirogue, because it will spend more time idle than in the water (like most boats) and I wanted it to be able to dry out while..."resting". Note that mine will not be used in situations where I am likely to be bouncing off rocks. More of a lake and slack water sort of a guy.

Regarding saturation, I can't help but be skeptical about it. I can see where thinned epoxy might saturate the surface plys, and soak into exposed edges, but I'm not sure I believe that core plys would ever get saturated. Seems to me that the glue line between the surface ply and the core ply(s) would stop that from happening.

What thinks the BS experts?

Regarding

 

[aub77]

It does not matter whether you fiberglass and epoxy encapsulate the entire boat inside and out....moisture will seep in and out. If you do not have an exterior grade of plywood (resourcinol glue; i probably mangled the spelling) then the plywood will delaminate--probably in one or two years from what I have seen and heard of from other builders. Boat building is too costly in time and money to ignore the grade of the glue...not to mention the mental pain of seeing your baby fall apart here and there over and over again.

 

[Lazyriverguy]

gbinga: I agree with your question on water proofin. Is it gonna be? I plan on using Smiths Penetrating Epoxy to seal the wood before glassin or fileting. I did read from the manufacturers papers the glue used in the prossess of the wood I bought is of the same compound that is used in exterior grade ply's. I dont know if it is or not but I figure if I seal coat everything with penetrating epoxy I should in general be Ok. (I hope)
Guess I'll find out.
Joe

 

[oldsparkey]

As one of the , if not the only person , I use the cheep wood ( 1/8th inch) to make my boats from unless I get a kit.

I epoxy saturate the wood and have not had any problems with water damage to them. I do several saturation coats and then glass them , the bottom is normally coated with several coats of epoxy and graphite for more protection.

If a person was worried about not getting the epoxy saturation deep enough into the wood then use some of the Smiths Penetrating Epoxy and it will be saturated.

I may look at it to simple but I figure that when the wood is epoxy saturated then what ever the glue is in the wood is immaterial since the epoxy takes over that job , while protecting the wood from the elements. Fiberglassed wood when punctured will cause problems , epoxied saturated wood will not.

Plus saturating the wood gives the epoxy when fiberglasssed something better to bond to/with then just raw wood being glassed.

I like doing things the K.I.S.S Way ( Keep It Simple Stupid)

Just my idea and no one else so it and a dollar might get you a cup of cheep coffee. :lol: :lol: :lol: A small cup of coffee.:roll:

Chuck.
PS. I have a pirogue that is 9 years old and it is in as good of shape as when it was made and it does get used , store inside when not being used. Made from 2 sheets of $9.95 Luann plywood. In fact during one Hurricane I filled it with water to have water to use when the power went out. Made a good water reservoir , no damage to it. It is epoxy saturated and fiberglass encapsulated and weighs 32 pounds at 15 1/2 feet.

 

[Lazyriverguy]

Thanx Chuck I feel better with each passin minute. Now If I could just get to cuttin wood.
Joe

 

[aub77]

Luan comes in "water resistant" and "exterior grade." Locally in the big box stores, the Home Despot carries the former and Lowes carries the latter. The only trouble with using exterior grade Luan is the lack of quality control but if you are careful selecting the sheets it can work quite well. Interior or even so-called water resistant glues should be avoided not matter what in my opinion. If you store the boat inside when not in use you probably could get away with it.

 

[oldsparkey]

I lucked out and found a local lumber supplier ( Not a big box store) who deals in the good Luann and they let me dig threw there stock to get the sheets with the grain pattern that I am looking for.

Chuck.

 

[hairymick]

G'day Aub,

I have used the cheapest and poorest quality interior grade ply imaginable on my Laker. It was the stuff I rejected for other builds. The boat is 18 months or so old now, and I use it more than any other.

It has bounced off rocks hard, played in surf and been dragged over oyster and barnicle coverd rocks and is as good now as she was on her maiden voyage. I am confident she will out last me.

Epoxy saturation will only saturate the outer veneer to the glue line.

With respect mate, I think you are way off the mark with some of your comments. Certainly, Marine Ply is superior but to say that interior grade ply WILL fail is absurd in my opinion. I agree with Chuck (up to a point) The ply is a stitch and glue boat that is encapsulated in quality epoxy resin and fibreglass is little more than the core that gives the boat its shape. Superior ply will privide a superior core and a prettier and lighter boat is all

 

[aub77]

Good Day to you too, sir. I hope you are well.

I have seen a canoe built from interior ply deliminate in a matter of months while it was stored in the guy's backyard not far from me. Not the best of situations to be sure; he stored it upside down on sawhorses without even a tarp. However, this same fellow had two small rowboats that he also built that he stored in same fashion for several years with no problems. One of the row boats was built from exterior pine and the other was built from meranti marine ply (really good stuff bought from bateau.com). Furthermore, I had some scraps from my first boat (a 14ft skiff) that was exterior luan and I had some scraps from a home project that were interior or actually "water resistant" luan. I left them outside next to the house hidden by the garbage can for a few months. The exterior grade held together just fine and the interior grade delaminated. Of course, neither were treated in any way (no epoxy or even paint).

By the way, parts of the canoe held together enough to become flower planters for a while after he tired of trying to patch the thing back together. Made me ill.

You are probably correct that I overstated that it will delaminate without a doubt. Boats stored inside when not in use like Chuck's would have a higher probably of surviving and maybe your Australian plywood is better than the crap we get here in the U.S. in big box stores. Who knows what glue the manufacturers really use but the interior glue is probably cheaper so them using resourcinol when not necessary is not likely.

Anyway, one has to make up one's own mind--that is part of the beauty of building your own boat. I just know that I would not take the chance. From what I have read on other boat building sites, my anecdotal evidence is not isolated.

 

[gbinga]

It does not matter whether you fiberglass and epoxy encapsulate the entire boat inside and out....moisture will seep in and out.

That is my suspicion, also.

However, lots of people have been doing this a lot of years and it appears to be a proven and effective method. I probably should spend less time worrying and more time in the shop.

My pirogue is very close to being ready for exterior paint. I'm tempted to take it to the lake for a pre-paint trial. Might do that tomorrow. If I don't drown I'll get pictures.

 

[tx river rat]

Well I have to agree with Chuck and Mick on this
I have built boats from Laun from home depot ,and Lowes, I cant tell the difference and some of my boats are 2 years old. I do bounce the of off rocks, drag them up on gravel and sand bars, scoot them across the bottom in shallow water nose up on concrete boat ramps, line them back up rapids
And so far they have done everything I want and I have not had one delamination.
I would be more concerned about putting a oil finish on plywood and what it would do to the glue than a little moisture.
Oh and here is another thing try putting a moisture meter on the ply you build the boats from at times it will surprise you, wood always has moisture content.
What I found that worked for me so far is fiberglass cloth inside and out
coat everything in resin, at least 3/16 ply (4 mm) and then go paddle.
Ron
If you cut all the way to the wood hitting a rock , sand around the scratch set the boat out in the hot sun for few hours glass it and go paddle again

 

[JEM]

Ron is correct. It can, and has been done many times.

The issue is consistent quality of plywood. Buy shopping for BS1088 marine grade ply, your chances of getting better quality are GREATLY improved. Plus it's wood whose properties fit nicely with boat building.

There's no quality standard...well there is but not a very strict one... for ply bought at a home improvement store. It's intent is not for twisting and bending.