The Wood is the Filling , Not the boat.

[jdupre']

J.D., just to add to what you wrote. You built 5 boats out of the cheap wood. Using expensive wood, I doubt you would have built 5. You might have built 2 or maybe 3 because of the expense of "good" wood. So let's say you built 2 boats. If I remember, those first two boats worked well but you were "not quite" satisfied with them for one reason or another. Now, if you would have stopped because of the expense, you would be using a boat that you "kinda liked". Using the cheap wood, you tweaked the design until you got something that works much better for you. And, on top of that, your building skills have improved tremendously. There is a reason apprentice carpenters don't start the first day with fiddleback maple and grade A Claro walnut. That comes later after the skills have improved.

I go back to my 73 year old friend who built two pirogues from luan. No glass-----no epoxy...........just painted luan with chines and a few ribs......$50.00. Both of them floated and are serious, no nonsense paddling machines. Will they last 20 years........probably not. Will they last 5-10 years with a bit of paint every couple years............I would bet they will.

Joey

 

[tx river rat]

This thread got resurrected but on another subject, If you glass a boat inside and out the wood quality isnt as important ,its just the filling , like foam , cardboard,you get the ideal.
Now all wood against a wood boat covered completely with glass is another animal , length of life and maintenance that you have to do to a ply boat is way more than one covered in glass.
The boats I am building now will last as long as you want them to.
the ss@g boats and the process have made my boats lighter and tougher. and where I put in and take out I dont want a 60 lb boat,
Ron

 

[beekeeper]

Joey
The main point I was trying to make, using your 70 year old friend example, is for another $20.00 or so he could have had a stronger and easier to build boat. Luan painted and not fiberglassed might work for very light use, but exterior grade plywood will work for light, and more demanding use. I agree about not starting with the best wood. Starting with the wood that is hardest to work with, and weakest is not the best choice either.

Ron
No need to be defensive of your boats or choices. My ideas were given in the context of information for new builders.
I stated that a skilled builder could build a good boat from luan. He can also build a better boat out of marine plywood. The design and methods used to do that could be chosen for a first build, but probably not if the person wants to keep it simple or has limited experience/skills.

beekeeper

 

[tx river rat]

Bee
Not defensive at all just making a statement , 12 or 13 boats out of laun and most I gave away or am still using. If I build with ply it doesnt make me any difference between laun and marine ply. I am going to cover it completely with glass.
If I am going to paint only I have to brace up more and I need to use the best ply available
But thats just me
Ron

 

[jdupre']

Bee, I agree that the exterior plywood would be stronger and probably last longer. I was just trying to show a "how low can you go" option. Now, using really good wood would be the best scenario, but for me it would double the cost of boat. Nowhere to get the wood locally so I would have to have it shipped at a cost of $100.00 or more just for the shipping.

Going with the "filling" idea, there are few structures out there that go through the stress and strain of recurve bow limbs. They perform at about 80% of their design limit on every shot. Some of the target bows use a foam cored, fiberglass covered limb. Maybe not the same as a boat panel, but it gives some idea of what strength can be obtained.

Ron said something about this in an earlier post. In a multipanel ply boat, the smaller strips of ply covered on each side and each edge with epoxy act like box beams. Box beams are much less sensitive to what's inside them. Structural steel and aluminum box beams have AIR as a filler.

Joey

 

[swampwood]

I will not use luan to build a boat again, but it does make cheap crating material.
The reason I made that statement is: It has a thin veener and the core material is not really a ply but a filler. It does not take any stress. Do not let it get wet. So if you fiberglass it, why use the wood at all :?: :?: :?:

 

[tx river rat]

Because we are talking a wood composite hull.I supose they make several kinds of laun but the stuff I used was layers of ply just like any plywood ,the only thing I found was they had a very thin outside layer.
Here is a boat I built and raced last year . 3/16 laun I ran small water falls rapids shallows and played pinball going down those rocky river, in the next race it was drug over loggs gravel bars.
You cant tell me that a boat can do all that and just scratch the finish on the bottom is junk .

Broke a lot of plastic owners heats :lol:
Swampwood you dont glass your boats?
Ron

 

[swampwood]

Because we are talking a wood composite hull.I supose they make several kinds of laun but the stuff I used was layers of ply just like any plywood ,the only thing I found was they had a very thin outside layer.
Here is a boat I built and raced last year . 3/16 laun I ran small water falls rapids shallows and played pinball going down those rocky river, in the next race it was drug over loggs gravel bars.
You cant tell me that a boat can do all that and just scratch the finish on the bottom is junk .

Broke a lot of plastic owners heats :lol:
Swampwood you dont glass your boats?
Ron

Ron,
I glass all the boats I build! Even the marine ply boats. Because I use 3-6mil. Okoume ply to save on weight. Now they are ply and you can sand without going through the veneer without trying.
I do think BeeKeeper is right about using bc ply instead of luan. It is alot stronger.
The luan we have here only has 2 thin veneers and a solid inner core.

 

[tx river rat]

Swampwood
See we all learn . the ply I use has three layers and a very thin veneer on the out side.
Like I said I have had nothing but good luck out of them .
Ron

 

[beekeeper]

Joey, we are on the same page. If one wants the cheapest "wood" boat possable luan may be the answer. My idea that exterior grade plywood is a better choice for a cheap "wood" boat. It won't be the cheapest but it will be the best value.
To me the BC ply boat meets the minimum standards for a "wood" boat. The luan built "wood" boat can be built to that same level but it will require more work, skill, or support wood. Each builder has to set his own criteriria and goals. If light weight and cheap as possable are priorities, luan may be the choice with the right design. If durability, strength, easy to work with, relative light weight, inexpensive, safety, and suitable for all designs BC plywood is my recomendation for a first time "wood" boat build.

A "wood" boat = a boat built without fiberglass = a boat where the wood is the boat.
"The wood is the filing, not the boat." is the definition of a fiberglass/wood composite boat, and the subject oy this post.

Maybe I shouldn't have posted here but Chuck said in the first post this was to help new builders. I have noticed most new builders talk mostly about KISS designs, keeping the cost down, wanting to learn, and they want a safe boat. If the new builder chooses to build a composite boat my ideas may not apply.

beekeeper

 

[jdupre']

J.D., you're probably on to something. The exterior ply you refer to is not light years behind fir marine ply in basic structure. It has substantial plies and decent glue. Marine ply has more uniform plies and waterproof glue. It would surely be an option to a new boatbuilder looking to get on the water for less money. New boat builders maybe ought to start with cheaper materials to work out design details and get experience in boatbuilding. I doubt any apprentice craftsman in any field starts out with the finest materials the first day on the job.

Now, if a guy is a first time boatbuilder, has pretty decent woodworking skills and is doing a fairly staightforward build with really good plans such as JEM's boats, then it might be the best idea if he uses quality marine ply. People like Tx River Rat, you and me that like to wing it and experiment, really can't justify the best wood on every build. Speaking for myself, there's a lot of things ( boats included) I wouldn't have or wouldn't do if I had to have the best of the best. At the time I built the Swamper, I just couldn't justify 3 or 4 sheets of quality ply and the $100.00 of shipping to get them here. Might have waited or not built at all. The Swamper has given me a lot of pleasure this last year and have no regrets about using luan.

Joey

 

[Kayak Jack]

The discussion about various quality of wood, it's strength, etc. underscores that the original idea is misleading and erroneous. On a composite structure - fiberglass over some core material - to state that the fiberglass is the whole strength and the core is insignificant is erroneous and misleading. The core is a large portion of the overall strength, and the stronger the core material (say, BS1088 vs luan) the stronger will be the finished product. If that core were 1/8" steel coated with fiberglass, it would obviously be stronger than 1/8" cardboard covered with the same glass.

 

[jdupre']

Core material does have a significant impact on the strength of the hull.........BUT. BS1088 standard ply might 2 or 3 times stronger than luan as a core material ............ don't know. But is 2 or 3 times the strength actually needed for the project at hand? Since I've been on this forum, I've not come across any boat made of luan that has failed because of the low strength of the luan/glass structure. Hairymick had a puncture in a luan boat but he was running white water and had a run in with a sharp rock, but the boat got him home. Tx River Rat's boats, by his own admission, get ROUGH treatment and have stood up to it very well.

Yes, BS1088 is a stronger product than luan, but for most purposes,luan is more than adequate for the job. "Weaker" or "not as strong" does not equate to "inadequate" or "unusable".

Just my 2cents.

Joey

 

[Kayak Jack]

Good point, Joey. I've not seen any wood boat failures. I'd guess that rocks might be the most worst underwater obstacle for them. Probably sharper and harder than wood or dirt. Also, I've bridged a boat or two going over beaver dams. And THAT is a no-no to do to a boat too.

Maybe, I prefer better material because I like having extra strength and hull integrity, whether it's needed or not. I do not want to hear my hull go CRACK when in either a fast river or a large lake. I'm fortunate in that I can get mahogany BS1088 plywood locally (30 miles away). Luan is more susceptible to having voids hidden within, and that problem is minimized by covering with glass and epoxy.

 

[tx river rat]

Now this conversation is starting to make sense, JD myself Mick all have proven laun will work great.
So will Marine ply
so will bc
styrofoam
cardboard.
Each has its strong points and weak points.
We are talking composite sandwich type construction.so the inner core is not the most important ,it is just part of the structure. Like was stated there are many structures that the shape gives the strength, try this a flat piece of 1/8 sheet iron , with the same amount of material, bend an angle then the a square tube then a rectangle . the load bearing and strength go up with each shape.
Contrary to popular belief marine grade ply is not stiffer than luan ,it is more flexible.Now it want flex as much as the Marine will so it depends on what you are going to do with it , a carefully chosen piece of luan might be better are worse according to the situation .
BC has a tendency to check after a period of time ,and I have a hard time finding 3 mm 3/16
Luan has been discussed to death so I want go into it, Marine ply is great but expensive
and hard to obtain in certain areas.
Built with what you can aford and all will build a good boat
Oh here is one for Swampwood of a luan deck

You can see there are some interesting things come out of luan.
Ron

 

[swampwood]

Ron,
If that is what interests you about luan, great.
You do know that luan has a good and bad side, right. I like plywood with a pronouned grain (that is beauty to me) :!:

 

[beekeeper]

Nobody has mentioned water resistance differances in the plywoods. What happens when the water gets past the fiberglass? The luan I have has not faired very well around moisture? I guess if "The wood is the filling, not the boat." it may not matter if the ply delaminates. Defenders of useing BC plywood instead of marine have said the glue in each is the same. I don't know. For the record I mentioned Bc in the context of first build and non fiberglass construction. Appearance is a personal preferance and judgement of the looker, but it is hard to make a skarf joint in luan.

beekeeper

 

[tx river rat]

Thats just luan with the paper thin vainer sanded of turned out pretty good for a first boat and sort of different.
Ron