Not if it's plywood. Plywood is multiple layers of would glued together. It's not something you rip and this is why it's made in so many different thicknesses. Plus you'd need a pretty industrial sized tool to rip or plane something 4 feet wide.

 Recently I substituted 6mm Sapele for 3mm on a WD12, it was cheaper to get two sheets of 6mm than one of 3mm. (?) On this project I probably added a little weight to the boat but the material seems to have taken the bends properly and there were no other issues.

 I'm not familiar with the Kaholo - if you could substitute the 9mm for the 4.5 and live with the added weight maybe that's a better option than trying to modify the plywood.

Wow that would really be overkill for the Kaholo.   Just finished building mine with the proper wood and it isn't all the light to begin with.   I would definately not use anything thicker that what is suggested.   Plus I would wonder if you could really bend the front of the boat into shape with that thick of wood.   Spend the money and do it right.  

Brian.

Hello all, I appreciate the input. I know that plywood is not usually ripped and all things being equal I would just order the right thickness. But at 1/4 the cost for 2 times the material it would reduce my building costs considerably. For the Kaholo it would save me about $370.

I agree that just using the 12mm for the kaholo would be overkill and way too heavy so that is not an option.

In terms of being able to rip it, I would not rip the whole sheet but instead break it down to manageable sizes. Then I would attempt to rip it right down the middle and send it through the power planer to finish. For the kaholo, the deck and the bottom panel may be too wide to easily rip, but other pieces are no more than 15 inches wide.

I have not heard why this would not work yet. Do they use inferior/thinner pieces of wood for the inner sheets? Would ripping it in half corrupt the structural integrity of the two halves? Also, if I plan to fiberglass the boat would it make more sense to fiberglass the factory outer layer or the newly created out layer.

Hmmm.   I have never heard of anyone ripping a sheet of plywood and don't suspect there is much chanch at all of it working.   Plywood is not a solid material by any means and the resulting surface you would get is likely to be terrible.   Plus it would take some really impressive machine to do it.   Even doing it in small sections would be really hard - some of the sections needed to build the Kaholo are pretty darn big!    Not trying to be negative....and I understand wanting keep down costs....but I can't imagine you can rip a sheet of plywood and have the result be anything you want to build with.    We will all be interested to hear what happens however.

Trying to rip the 9mm on edge is not going to work very well, and even if you can somehow pull it off, you will have to plane it and then you'll end up with questionable ply orientation at best . Save the 9mm for another project and get the right stuff. 

I think you should buy the cheap wood and when your efforts to split it fail, you will know it was a truly dumb idea. Be sure to set aside enough cash to buy the thinner wood, though. -Wes

:)   You say it like it is twofootartist!    But you are correct....doing it the wrong way with the wrong materials just ends up costing more money in the long run.

If you can't afford to do it right than wait until a later date in time when you can.    Nobody really "needs" a Kaholo after all so if it is coming down to a few bucks here or there than just wait till next year.

Best of luck.   I guess if one thing is proven...it is that you will get honest answers here on the forum!

Look, if the 9mm okoume is truly high-quality, buy it and resell it on Craigslist for a profit.  Set aside the money.

I guess after hours of grinding you'd have something resembling 4mm, which is still too thick to make the twist in the forward bottom panels on a Kaholo.  I think I'd rather see you do a lauan Kaholo [involuntary shudder] than waste a lot of good 9mm, which SOMEONE out there needs, for sure.  

Folks, I appreciate that it is not something that is normally done. The closest thing I have gotten to a response about why it wouldn't work is that there would be questionable ply orientation. I looked into it and I think the main problem is that the 9mm is made up of 5 layers of wood so splitting would leave you with 2 layers on each side. The 3mm has 3 layers of ply.

As far as Wes calling it a truly dumb idea and the other negative comments, it is one thing to have an actual idea of why something does or does not work it is another thing to not have any constructive idea and to be critical. Group think is great unless it keeps you locked into only one way of doing things. For a first and sincere question the feedback that I got was that of a bunch of follower not it alls that cannot answer a simple questio. Why? But I guess that takes actual work and thought and simply saying "because that's not the way it's done" is lazy.

It CAN be done! Happy now? However, a few Kaholo panels are about 30" wide so you will wind up shaving the ply down with hand planes or portable power hand planer.  One ugly job for sure.  It is a task that most of us who work with wood (I've been building boats for decades now) view as borderline insanity. 

Wanna go cheap? Door skin. Or get friendly with a local big box lumber store (Lowes Home Depot) or your nearest lumberyard. Here's the deal: nice plywood is shipped with sacrificial sheets on the faces of the stack. They are dunage to the lumberyard, so grab a pile of those sheets - similer to door skin - and you should be able to get usable Kaholo parts out of them.  Not marine wood but so what - you will saturate inside and out with epoxy and the board isn't going to stay in the water 24/7.

Yes, it'll be a lot of extra work, but you could do it.  Your saw would cut off most of the middle ply, so you'd be left with two 2-ply panels, each with a thickness of about 3.5 mm.  I imagine you'd cut your narrower panels out once from the 9-mm ply, then, after the ply is ripped in half, you would have two matching panels for building.  Keep the factory sides on the outside for best finish results.

Plywood is manufactured with an odd number of plys for structural benefits (Google it).  You would be using 2-ply plywood, so might have some issues with bending in ways you don't want (strength shouldn't be an issue after fiberglassing).  That could be worked around creatively until you have applied a layer of glass to the hull.  Also, I'd be careful to keep stitch holes farther from the edges, rather than closer, to prevent tearout in the more highly stressed areas of significant bends.

If you do try this, and aren't just trolling, I wish you luck.  The result could be a very unique craft that looks quite like an ordinary Kaholo.  If you run into problems, let us know.  We'll try to help.

My gut feeling about many of the earlier responses is that the responders see you as trying to push a car up a hill with just your bare hands.  They'd rather see you hop inside the car, start it, and drive up the hill; quicker and easier that way.

Happy building

I change my mind and would recommend that you do it...right away.   I would choose to listen to those on this site that have spent their lives building these things.   But could you pull this idea off it you have some very expensive equipment, all the time in the world, and don't care if the boat looks all that great?   Maybe?  

What I did once is partner up with 4 guys and bought the right stuff from a supplier and got a discount that way.   Maybe want to think about that and see if you know a group of guys that may want to go in with you on an order?    Or just by the non marine stuff like hokey recommended.

Hokey, thank you for the tip on the door skin. As far as "happy now" I really do not care if it works or not. That is why I asked before I got it. If you look at my earlier post, I realize that the 30" sections would be too much work to plane by hand so I would go with 3mm ply for those pieces.

Regarding the second to last post, that is the info that I was hoping to get. I did not cosider that the wood would bend in ways that the design was not intended for. Also the consideration on the location of the stich holes is something that I would not have thought about either. I apreciate the feedback.

I know that these forums can be super helpful. That is why I posted the question here. I also know that people make a lot of mistakes being penny wise. But I also think that things get accepted as the "right way" without critical thinking and there is no room for any other way.

When you are starting a project with very little wood working experience that is going to take a considerable amount of time and money there are a few different ways to go about it. The prevailing input that I got was do it the "right way".

But for somone like me with little wood working skill and no boat building skill paying $700-800 for the right wood and the mas epoxy and spending months and months to try to achieve the craftsmanship so cherished on these forums and likely still coming up short, it makes more sense to do it "gasp" cheaply. If I was only going to make one boat it would make sense to try to make a ferarri my first time. But I plan to make a few of them so I will go cheap. And when you see me on the water in my mishapen and ugly  kaholo in a month my smile will be just as big as the guy on his kaholo that took him a year to build and cost him three times as much.

All these hobbies started with some guy who just wanted to see if he could build a boat with the stuff in his garage. Then they get hijacked by old guys with too much money and egos. I repect the craftsmen on this website. You have a ton of knowledge and I appreciate your willingness to share. But please try to remember what it was like to just be starting out.

I actually think that it is a bad idea to buy the 9mm ply. I got a few constructive thoughts on why i would not work and it makes sense. I think that the biggest problem is 2 veneer sheets instead of 3. If anyone needs some 9mm okoume in the portland OR area let me know and I can tell you where it is at.  Even you klaver.

As for the kaholo, I do think I am going to build one. I think I am going to shape my own board using AKU shaper and build it using cedar strips instead. The cedar is much chepaer and I can use less epoxy. I am sure that I will make a ton of mistakes but that is part of the fun.

IMO, planing 9mm down  to 3mm is a tremendous waste of valuable natural resources. For me, that's off the table unless it's small parts. So, considering that you are dealing with plywood sections up to 30 inches wide, the best option is a big bandsaw. If you're lucky enough to know a foreman at the local plywood or veneer plant, they would likely have just the equipment you need to rip the 9mm. A case of beer might do it. 

Barring that, here's an idea. Build your own bandsaw. I know,  that sounds intimidating, but not if you have an old bandsaw you can rob for  parts. My old craftsman 12" would make a great donor. If you're  still with me, you need a sturdy frame(not bed frame angle) and some welding skills or a good friend with steel and welding skills. For a band saw of this capacity, the blade will need to be under a lot of tension, so a sturdy steel frame is paramount. Your going to use the blade wheels from the donor and mount them to the frame. I'd use steel channel and  cut slots in the channel to mount the wheel axle bolts so you can adjust wheel height (panel thickness). The wheel supports will pivot forward and backward. Fabricate cables with turnbuckles and attach to each wheel support (there should be 4). The turbuckles will be used to tension the blade and make allignment corrections. You'll also need to weld on the motor mount from the donor bandsaw. Now comes the hard part. You'll need two blade guides. My old craftsman has one assembly, but since your building a 30 inch capacity bandsaw, you really need guides on each end. Beg or borrow another guide assembly from a good friend or someone you don't think you'll ever see again. You could make your own, but I'm trying to save you some time here. With the guides mounted, you need to source a custom blade, but there a number of sources for custom bandsaw blades. No problem, but  you want a pretty wide blade since you want to minimize deflection. Ok, now you're almost there. Need a solid base. I'd recommend 3/4" MDF. It's cheap and I know you're on a budget. One last step. You need an infeed roller to hold the plywood down flat. I'd go for 4" shedule 40 PVC. You'll need to add end caps with fairly precise centered holes for the axle. Attach the roller assembly to a couple of pivoting angle iron pieces attached to your base frame. Use a couple of old trampoline springs to hold the roller down. Everyone who has had kids likely has a bucket of these out in the garage somewhere so should be easy to find. Now your ready to fire 'er up. Wait! Need to set the thickness of the cut. Put a couple pieces of 3mm under the blade wheels, loosen your wheel bolts an slide them down on the 3mm. Tighten up the wheel bolts and your good to go. Handy tip: use a variac and start it up slow. Use your turnbuckles to make your final precise blade wheel allignment.  There you go! Now you got a big honkin', plywood splittin' bandsaw!  (disclaimer: neither the author or this website accept any responsibility for injuries caused by the misuse of the intended purpose of this post (humor)). 

Cheers!

Dave

Best of luck.  When it is done....post something for eveyone to see and let us know what new ideas you ended up coming up with, what worked, what didn't work, etc.   Enjoy.