Thread: Plywood for small boats.

Aah, the million dollar question. First ask yourself, "How long do I want the boat to last?" If you plan on using the boat lots and keeping it for a very long time, I would buy the best ply available to me. It's not a very nice experience if all your hard work starts to fall apart.

Your choices for boat plywood are: (Ranked most expensive to cheapest)

1. Genuine Bruynzeel Okoume/Gaboon marine ply from Denman Marine (High quality, no voids, certified, and 25-30% lighter and made in Europe)
2. Genuine Hoop Pine marine ply made in Australia (eg. supplied by Mr Ply & Wood but other vendors as well. Very high quality, no voids, but without the lightness of Gaboon)
3. Asian made "Gaboon" marine ply of doubtful quality (Often just the top faces are Gaboon and there can be voids)

In reality, the ply cost is a relatively small component of the cost of building a boat.

If you used Hoop marine ply, you could offset some of the weight by using Paulownia for framing instead of Oregon. It is locally grown in plantations, very light, easy to work and very strong. It resists splitting, warping, rotting, glues well and is ideal for building lightweight boats. Looks good too. I used it for building a GIS that ended up very light and strong. Use it anywhere you would use oregon, except perhaps a motor mount on a transom or for spars, although it works well for infills in hollow spars. It's perfect for lightweight foils too.

I found the cost of Paulownia very reasonable, even including the freight delivered to my door.

Thanks wooden eye.

Bruynzeel in syd said they have marine ply and gaboon marine ply. Am I correct to assume that their marine ply is the hoop pine? And their light weight option is the Asian gaboon.

I've been looking at some Spira plans too. He states you can use good quality construction ply so I was wondering if getting wood all the way from tassie is over kill?

tough choice.... I already have a kayak, a canoe and do a lot of kitesurfing.... Garage renovation is so I fit all the toys. All are kept undercover and not used heaps... Because I have many to choose from.

mike

Just to echo the question, "how long do you want the boat to last?" The original Quick Canoe design was about knocking together a... quick... canoe... to get on the water right away. Maybe even AT your vacation destination. As such, I think the designer made some trade-offs that would make sense for a short-term experience rather than a long enduring heirloom boat.

The motorized version brings other considerations into play, but you should probably feel comfortable with economizing on the wood so you can have fun with this one (a quickie?) while preparing emotionally and financially for the next build. Or maybe just go straight to the punt?

Originally Posted by schmik

Thanks wooden eye.

Bruynzeel in syd said they have marine ply and gaboon marine ply. Am I correct to assume that their marine ply is the hoop pine? And their light weight option is the Asian gaboon.

I've been looking at some Spira plans too. He states you can use good quality construction ply so I was wondering if getting wood all the way from tassie is over kill?

tough choice.... I already have a kayak, a canoe and do a lot of kitesurfing.... Garage renovation is so I fit all the toys. All are kept undercover and not used heaps... Because I have many to choose from.

mike

I would not assume that their "other" marine ply is hoop. They should be able to tell you about the product they sell but if it is made in Asia it certainly won't be Hoop.

If you want to build a boat that looks great, that you can be proud of, is light and strong, then the stuff from Tassie is definitely not overkill. For a quality project, it's essential. However, it's really what you want, and like anything, you pay for quality. One aspect that I didn't mention is the ability to produce a nice curve when the ply is bent. The cheap ones can kink due to voids or inconsistent core densities. Also, take any claims that the Asian made stuff has been made to BS1088 standards with a grain of salt. The Tassie stuff comes with a written certification whereas the Asian stuff is just an unsubstantiated claim.

When I was selling my GIS, every single caller wanted to know what ply had been used in the construction. I could tell them it was "the best"!

Thanks guys. It's likely that I would leave the quick canoe at my parents holiday house.(hawks nest). That way I only need to take up the little outboard. Mostly used for fishing in calm waters. It's in my nature to use the best materials and over engineer things... Just a bit short on cash at the moment.

I want do the quick canoe first because I already have the 2hp and have never built a boat before. Probably best to save the money and get enough wood for both boats shipped from tassie at the same time.

And then take it back to tassie.... I am spending 4weeks there over summer so having the punt or quick canoe on the roof would be great. Probably wont have the money for a 10hp out board for the punt by then anyway.


how long do I want to keep it for? Dunno.

Sounds good Schmik! As Dave has mentioned, common sense would rule out spending silly money on ply for the Quick Canoe. Reserve the nice stuff for a really nice project where finish and reliability are important.

Howdy,

Downside of Hoop Pine ply is the sheet size - it is a decidedly un-international 2400 x 1200 which is shorter and narrower than international sheets - so none of my designs are set up for the small sheets.

Bruce is spot on ... if you want the boat to be light and last you can get the Joubert or Bruynzeel plywood from Tasmania, though some like Duck Flat in Adelaide distribute it as well.

If you want to go cheaper any good looking exterior or marine plywood. Look for nice faces with no knots and very few voids visible looking at the sheet edges in the shop.

Some of the Chinese gaboon ply is OK, most is terrible, so you really have to see it and get a guarantee you can return it if there is a problem with waterproofness (boil an offcut for 20 minutes and then let it dry, repeat) or you find voids in the middle.

Look for 2440 x 1220 sheets, though quality gaboon is 2500 x 1220.

HOpe this helps
Michael

Originally Posted by Boatmik

Howdy,

Downside of Hoop Pine ply is the sheet size - it is a decidedly un-international 2400 x 1200 which is shorter and narrower than international sheets - so none of my designs are set up for the small sheets.

Bruce is spot on ... if you want the boat to be light and last you can get the Joubert or Bruynzeel plywood from Tasmania, though some like Duck Flat in Adelaide distribute it as well.

If you want to go cheaper any good looking exterior or marine plywood. Look for nice faces with no knots and very few voids visible looking at the sheet edges in the shop.

Some of the Chinese gaboon ply is OK, most is terrible, so you really have to see it and get a guarantee you can return it if there is a problem with waterproofness (boil an offcut for 20 minutes and then let it dry, repeat) or you find voids in the middle.

Look for 2440 x 1220 sheets, though quality gaboon is 2500 x 1220.

HOpe this helps
Michael

Very good points MIK. I always forget about the sheet size variations! The extra large size of the ridgey didge stuff does offset the extra cost a bit.

Is the quality of the plywood still as important if it is to be glassed over both sides and edges ?

IMO, if it is in a Rigid spot then not so important.

If it will flex at all then use the best you can afford.

That is based on building some kite surfing boards, they flex a lot and the cheap stuff delaminates due to the flex, even though it was totally wrapped in glass.


mike

Originally Posted by johnnyroberts

Is the quality of the plywood still as important if it is to be glassed over both sides and edges ?

Howdy,

It is often said on the internet. But the problem is that by the time it's glassed it costs more than getting reasonable plywood in the first place.

Not to mention the unpleasant labour fairing and smoothing glass.

The weight increase is very significant too. It is not so much the weight of the glass, but the lightness of the timber. And there is an enormous difference picking up a boat that has been glassed vs one that has not.

The problems with weights is our experience is not of a smooth curve.

A Eureka canoe out of gaboon plywood with glass taping only will come out around 40lbs. This is a really comfortable lift for one person. But add ten pounds more and there is really significant sense of weight. Add fifteen and it is a struggle if much distance.

Some say "it gives extra strength" but something is screwy in kayak design where they are suggesting 4oz glass over the whole outside of the 4mm ply (which is not uncommon. Even more interesting is that CLC and Pygmy and others are now starting to recommend glass on the INSIDE of boats too.

My counterexample is the 16ft Jarcat which has sleeping accommodation, quite a bit of sail including a big genoa (lots of load on the hull) and often quite a big outboard (by sailing boat standards) to go fast when needed.

Construction is 4mm ply with 2oz glass on the outside.

It really indicates that glass on kayaks and canoes is overkill in some senses considering average use patterns.

I'd trade less glass for more portability any day

Best wishes
MIK

From my reading... the fibre glass offers very little in strength and rigidity.
What it does do is provide resistance to abrasion.

So.... the bottom half of a kayak or canoe can do with some fibre glass. If you are in a rocky spot that is....

Howdy,

Yes ... it doesn't add much stiffness for weight.

But one exception. it is nice to use 5 ply (5 layer) plywood for boat bottoms if possible. This is because with 3-ply the middle veneer across the boat is solely responsible for thwartships stiffness so must resist by trying not to bend - poor little thin veneer. And it is only a couple of mm thick. The two outer veneers give longitudinal stiffness very effectively because they are spaced apart by the middle veneer - one will be in compression, one in tension - which is a much more powerful version for resisting load.

So when you have 5 veneers then the ply is set up to resist longditudinal and thwartships loads very nicely.

HOwever ... if you add even a very light glass to 3 ply plywood it will allow the middle veneer to brace against something for a big increase in stiffness.

My take on that is that the glass still adds a lot of weight relative to the ply - particularly if you follow other advice on the net and think that 4 or even 6oz is appropriate for the small light boats we are interested in. Experience shows that 2oz is adequate to protect 4mm ply for quite substantial boats like the Jarcat. 16ft with sleeping accom.

so in that case the light glass has been used to prevent the need to jump up to the next size of ply. That's how glassing can work to provide stiffness in one particular set of circumstances.

As to abrasion resistance ... glass is excellent for abrasion. However, the question always needs to be asked ... what sort of abrasion is really expected and what sort of coatings can deal with it.

The coast of Maine is very rocky and jagged because of glaciation. But Christophe in extensive camp cruising has found that with an unglassed Goat that the epoxy and two pot paint has been more than adequate. There has been some wear - a few scratches in the paint - in the first couple of feet of boat, not going through the epoxy. he called the rest of the bottom "pristine". That would be about at the two year mark.

Christophe Matson - New England - hovering goat..JPG

You can see the rocky shores in all directions.

MIK

I fish in estuaries (and brackish rivers) out of my canoe (fibre glass) and kayak (plastic). They get some pretty nice scratches from going over rocks or fallen trees.

I will do my best NOT to fibre glass the bottom of the quick canoe. I tend to over engineer things and in this case i want light weight.

mike