Making a two piece canoe, seeking advice..

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jmburbach
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Making a two piece canoe, seeking advice..

Post by jmburbach »

I have an old fiberglass canoe I was thinking of converting into a two piece, bolt together hull. I figured to just epoxy in a couple plywood bulkheads centrally to cap each half and receive the bolts to bring the hull together. I haven't decided yet if I should cut the canoe in half first and then install the bulkheads, or install the bulkheads first leaving enough gap to saw between them afterward. Cutting it first would make tracing the bulk head to fit easy, but could require bracing the hull well first or risk it twisting and going out of shape too.....anyway..

For gluing and filleting, would the regular wood flour be ok for joining fiberglass and plywood and be strong enough, or should I consider something like chopped glass or similar for this purpose? With the bulkheads glued and filleted on the inside, would that be strong enough to hold the together you think? Should I also put a layer of glass tape over the fillet, maybe a few little gussets between the hull and bulkhead? Would it be necessary to glass the outer side of the bulkhead, or just fill, fair, seal/paint it good enough?

Maybe a slightly off the norm question, I don't know. I do know I'll be adding some extra weight doing this, but I am ok with that for my uses. I don't want to overdo it and add more than necessary though, or not do it properly and have it separate either.

Thanks for any advice..cheers!



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sitandfish
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Re: Making a two piece canoe, seeking advice..

Post by sitandfish »

jmburbach wrote:I have an old fiberglass canoe I was thinking of converting into a two piece...Maybe a slightly off the norm question, I don't know...
For people going through a divorce the question probably makes sense. How else would you divide assets equally? But for any other reason it is hard to get past the initial shock of the question. But, I will try.

I can never make sense of having a frame (double frame) in the middle of a boat. With a canoe it means you can NEVER solo paddle the boat. And if the reason is to make it easier to move by truck or car... it just doesn't add up. It actually makes more sense to me to make a 3-part canoe than a 2-part canoe.

Want to make a 3-part canoe? :doh:
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jmburbach
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Re: Making a two piece canoe, seeking advice..

Post by jmburbach »

Well, 3 piece is always a possibility as well...three 5' something sections would foot nicely in the car... 8)

I guess my real questions are about bonding fiberglass and plywood. What would the proper epoxy additive to consider for this type of application..wood flour, chopped glass, ratios? Would the glue and fillet then be considered adequate for the job, or if I should include some extra structural support? And also if glassing the fillet and outside of the bulkheads would be necessary or a good idea?

cheers!

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Evan_Gatehouse
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Re: Making a two piece canoe, seeking advice..

Post by Evan_Gatehouse »

I designed the FB11, the 2 part nesting dinghy so I think I am qualified to answer your questions:

- install bulkheads first, then cut hull
- use cardboard and some hot melt glue to make a template for the bulkheads. Trim, fit, cut with scissors, overlap new cardboard until you get it right. A small gap is ok because you will fill the gap with epoxy glue and tape over
- wood flour is sufficient. Fillet and tape inside and out. (Grind the outside radius after cutting apart so the tape will stay down)
- little gussets are probably not required.
- use rubber washers and s.s. washers on the bolts that connect the 2 halves
- make one half slightly shorter so you can store part A inside part B (assuming you have no thwarts in the way)
designer: FB11/GV10,11,13/ HMD18/
SK17,MM21/MT24

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sitandfish
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Re: Making a two piece canoe, seeking advice..

Post by sitandfish »

jmburbach wrote:Well, 3 piece is always a possibility as well...three 5' something sections would foot nicely in the car... 8)

I guess my real questions are about bonding fiberglass and plywood. What would the proper epoxy additive to consider for this type of application..wood flour, chopped glass, ratios? Would the glue and fillet then be considered adequate for the job, or if I should include some extra structural support? And also if glassing the fillet and outside of the bulkheads would be necessary or a good idea?

cheers!
Sometimes just because you CAN do something doesn't mean it is a good idea. I mention three pieces because I can't find any good examples of two piece canoes. Going past the BIG bump in the middle I see this problem:
Image
Not sure where the savings in room is? If the canoe was on top of the truck you would have room in the bed of the truck for camping gear or... WHATEVER. I don't see any room in this truck? But, he DOES have a canoe that is cut in half. Hurray! :roll:

The three piece may allow you to kneel in the middle. But, this kind of frame may allow you to sit in the middle?
ImageJust some thoughts. :wink:
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jmburbach
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Re: Making a two piece canoe, seeking advice..

Post by jmburbach »

Transportation is not the major motivation for this as car topping the canoe is not so bad. The real problem is that I'm moving into a smaller apartment which does not have a large enough patio to store the canoe as I do currently. I can't leave it outside, I don't want the cost and hassle of a trailer just for a canoe, and don't wish to pay for off site storage somewhere...and since my significant differs on the idea that a canoe in the living room makes good conversation piece...I have to seek other methods. :wink:

Thanks for the suggestions and ideas so far, very much appreciated. I like the idea of making one end a little shorter so they fit inside each other. That would make it possible to really tuck it away in a corner of the patio easily, and should make car topping solo easier too. That last picture looks like a good idea for a way to allow for a seat on the central frame for a two piece as well.

Of course three piece canoe has some appeal as well. Pieces would be small and light, store easily enough, and would even fit inside the car behind the seats with the hatch closed...though putting something that has been soaking in the lake/river/swamp all day inside the car may get me into trouble as well if I'm not careful. ;) Could also provide hard points for lashing an outrigger or even small sail if I got bored.

I was thinking of using 1/4" plywood for the bulkheads, with small pieces glued on to double up where the bolts go through. Would that be sufficient, or should I use something thicker?

thanks guys...cheers!

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sitandfish
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Re: Making a two piece canoe, seeking advice..

Post by sitandfish »

jmburbach wrote:...The real problem is that I'm moving into a smaller apartment which does not have a large enough patio to store the canoe as I do currently...and since my significant [other] differs on the idea that a canoe in the living room makes good conversation piece...I have to seek other methods.
Clearly understood. I keep up with another boating site that deals with very light boats called "microskiffs". They have a saying that goes something like, " You know you own a microskiff if your first move before a hurricane is to move your boat into the living room." :wink:

Evan will probably help you with the plywood thickness. Maybe you can tell him if you are going to use full height frames (I don't think it matters if you cut out the middle like a doughnut) or if you want to use "U" shaped frames like the picture where the guy is putting the seat on top of the frames?
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Re: Making a two piece canoe, seeking advice..

Post by Arm&Hammer »

I am about finished with a canoe prototype that I have been working on for a while. It is 12', but three pieces. The front portion is 3' long, the middle portion is 5' long, and the rear portion is 4' long. The seat is similar to the one shown (cane), and is removable. The advantage of this is that I can nest the 3' inside of the 4', and then the 4' inside of the 5'. So the nested canoe is 60" long x 29" wide x 14" tall, and there is still room inside the 3' section to store accessories (seat, life jacket, anchor, etc.). This is also small enough that I could ship it UPS ground w/o oversize charges.

I realize that this is a smaller canoe than what you have, but I think you get the point. I was going for the ultimate in compact size for the same reason that you mentioned - my brother lives in a condo, and space is limited. He said that he would love a canoe, but had no place to store it, so the wheels started turning.

If I were to do it again, I might make the center section 6' and the two end pieces 3' for the following reasons:
-The two 3' sections would still fit inside of the 6' section.
-This would enlarge the center section so that I could fit a cooler behind the seat.
-Not that I am concerned, because I have already taken her out for a trial run, but this would reduce the stress at the bulkhead (there is less stress the further that you get away from center).
-It would also be easier to build since both bulkheads would be the same size.

So if your canoe is 15' long, and you want to do the three piece thing, I would probably go something like 3'-9", 7'-6", 3'-9". This would be short enough that you could stand it on end in an apartment.

For the bulkheads, I originally built with 1/4", taped inside and out. I was concerned that this had a little too much flex, particularly at the rear bulkhead, so I added a 1/8" thick piece on the inside of each bulkhead, which was probably overkill. For your canoe, if you are going to do it in 3 pieces per the dimensions above, I think 1/4" will be fine if you are only going to use it as a solo canoe. But if you plan on two seats, I think you need more, atleast 3/8". It would probably be best to decide how long your sections will be, and then ask Evan for a thickness recommendation.

On cutting the sections, I did what Evan recommended. Epoxy glue/fillet/tape both bulkeads inside the canoe, using something to space the bulkheads the thickness of a saw blade. Then drill your bolt holes, as the canoe is still in its natural alignment and the bulkheads are locked in place. Then cut between the bulkheads. As Evan said, you will want to radius the outside edges and tape those as well.

I plan to take some photos in a couple of weeks after paint. When you get your's finished, please post some pics also.

jmburbach
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Re: Making a two piece canoe, seeking advice..

Post by jmburbach »

Your prototype sounds interesting, could fill a niche for those living in the city without much space like myself. And thanks for sharing your thoughts and experiences, good to hear from people have done something similar already. The more I think about it the more I'm inclined to go with three pieces as it seems it could have many benefits over two pieces...though a tad more work and weight.

The canoe will need be strong enough for two aboard plus a little gear, and I'm entertaining the idea of adding an outrigger and small sail for fun at some point, which will also add some stress to the hull. I'm still leaning towards the 1/4'' ply as I think it would be strong enough. I will double up with some offcuts where the bolts go through to add a little stiffness and spread the load as well. But I'll certainly heed advice of anyone more knowledgeable if they believe I should go thicker.

cheers

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Re: Making a two piece canoe, seeking advice..

Post by Evan_Gatehouse »

- 1/4" ply with small doublers will be fine. 5/16" s.s. bolts with s.s. wing nuts and fender washers please.

- don't cut down the frame too far; if the cutout is below the loaded waterline the joint WILL leak.

- The most stress is on the top and bottom of the frame, very little in the middle (bending loads basically) so cutting a cutout in the middle is possible as long as you pay attention to previous post. Thus a tall full height bulkhead is a lot stronger than the cut down one.

(The FB11 uses cleats on either side of the bulkheads and a seat that slips over the top with a friction fit. Might be useful to consider if you want a seat in the middle). You can always add lower fore/aft seats that sit on side mounted hull cleats with velcro to secure, but remove easily for nesting.

- if you are maybe going with a sailing rig I would go with 3/8". Sailing rigs TWIST the hull significantly.
designer: FB11/GV10,11,13/ HMD18/
SK17,MM21/MT24

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