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Maybe a good idea, maybe not.

Posted: Sun Dec 28, 2008 6:14 pm
by Derek Bowen
Hello there, İ very much like the DK Touring Canoe free plans. İ have sat over the forum for a few days now and very impressed İ am. İ,ve done a few concept modification drawings trying to come up with a canoe İ can use here on the Dardanells for touring/camping. This is a fairly busy shipping channel but the lanes are tight and being a channel, most of the time the biggest waves we have to face are bow waves. İ would very much like your opinion on my project/fantasy. First is boyancy chambers in bow and stern. Second is bulkheads and hatches for stowage in bow and stern. İ dont think that these changes will raise any eyebrows. The bıggy is to make a breaking joint across midships. (Maybe this is the time to pour yourself a large perspective n coke). İf İ move the two main frames a bit fwd and aft of there designed position and add a beefy pair of additional frames at the cut line mıdships,that will, in effect become the flange for bolting the two halves together. A 6 or 7mm SS bolt every 8 or 10 cm and a liberal application of silicon sealant should do it. İ do need a larger canoe for touring and carrying wife and camping/cooking gear but when the weather turns icy (as it is at the moment) İ dont have anywhere to store her out of the elements (the canoe that is). İf İ can unbolt the two sections they can stand up in the workshop or at least on the balcony. İ can see how odd this must sound (it sounds damd odd to me) but as far as İ can see it should work.
What do you think. İ will do me best to work up a set of scale drawings for your consideration in the next few days.

Re: Maybe a good idea, maybe not.

Posted: Sun Dec 28, 2008 6:43 pm
by jem
It's possible buy you need 9mm bulkheads on each half.

The other challenge you'll have is leaks.

Re: Maybe a good idea, maybe not.

Posted: Sun Dec 28, 2008 7:47 pm
by Derek Bowen
Hello Matt, thanks for the quick reply. İ certainly understand the leaks issue. İ think if İ increase the width of the frames to 60 or 70mm and stagger the bolt pitching İ wont have too much trouble (Ha Ha). İ really need to spend some time to make scale drawings. When they are ready İ will send them to you and hopefully you or others on the forum can put them to some use. İ am an aircraft mech with an imagination. We,ll see where it leads Aye.

Re: Maybe a good idea, maybe not.

Posted: Mon Dec 29, 2008 1:48 am
by Jimmy W
You might want to look at this: ... ingy1.html
But stopping leaks through the bolt holes might be a problem as you and Matt already mentioned.

Re: Maybe a good idea, maybe not.

Posted: Thu Jan 01, 2009 12:08 am
by Kayak Jack

I've seen canoes like you describe in Sault Ste Marie, Canada, at the Canadian Bushplane Museum. It came apart into three sections, one end section was shorter than the other one, and nested within it. then, both end sections nested within the center hull section.

A ring of sealant around the mating edges of the joint would be a protection against leaking. Your bolt holes would be in that flange, inside the boat. Length of each sub-section, placement of seats & thwarts, etc. are critical to the nesting operation. And, no take-apart hull will ever be as strong as a single piece hull. So, you would have to use it more tenderly than a real canoe.

Have you looked at an inflatable?

Re: Maybe a good idea, maybe not.

Posted: Thu Jan 01, 2009 6:21 am
by Derek Bowen
Thanks for that Jack. İ understand that there needs to be a compromise here over the general strength of the canoe. İ am strictly a fair weather paddler and there is no white round here, come to that, İ dont think there,s any white water in the whole country. İ am Trying to build the boat to suit the needs of the place. Cruising, camping and just aimlessly paddling about on a sunny afternoon with a cold tinny. Making the boat in two halves is purely to suit this house. No garage or even a sheltering roof to keep the sun off. When İ get around to it İ will photograph all the jiggery pokkery and post it for all to see (and laugh over). İ am an aircraft mechanic (ex RAF) so İ have a pretty good idea of structural strength and what happens when you fiddle with somebodies well worked out design.

Re: Maybe a good idea, maybe not.

Posted: Thu Jan 01, 2009 10:44 am
by Kayak Jack
OK, Derek, now we have a common language. I'm a retired aircraft maintenance officer (USAF), and a pilot. Well, a student pilot yet, but I do keep the pointy end forward.

Remember stations on an aircraft? Body stations measured back from the nose, or a point out in front of the nose? Water lines measured from the ground when sitting on an extended landing gear? And, wing stations coming from the centerline out? Think of your canoe hull similarly. It is a three dimensional grid.

Consider cutting the boat not at its center body station, but off center. This way, one end can nest inside the other, and will have a smaller footprint. Your mating surfaces would be, in effect, a large rib extending from gunnel to gunnel. Four, maybe five bolts through both mating ribs, would secure it. Your sealant would be along the outside edges of those mating ribs.

Royal Canadian Air Force used to flay a cargo bird that folded in the middle, the CL-44. It was a four engined turboprop. Had a hinge on one side and bolts on the other. You may have come across one in your travels.

Re: Maybe a good idea, maybe not.

Posted: Thu Jan 01, 2009 1:42 pm
by Derek Bowen
At last, someone who understands. Your right on the money Jack. The connecting frames will be a bit of over engineering İ expect since the aircraft ethos of making a repair or modification stronger that the original structure is still alive and well here. My kitchen unit has doublers fitted on all cut throughs. The bolt pattern İ am planning to use to join the two hull sections will follow the arraingment of an integral fuel tank access hatch. Staggered pitching and not too far apart. 6 to 9cm should be OK for a canoe. 747 tank hatches are pitched at about 3 or 4cm. İ am really looking forward to a bit of technical work. For sealing, silicon sealant is easy to get here and with the new frames being around 6cm deep İ dont anticipate any leaks. (famous last words). Nesting one half inside the other makes a lot of sense but İ dont know yet if it will work for me. My design mods are not yet finalized so its another component to add to the equation. Bloody good idea tho.
İ never did meet a CL 44. İ,ll look it up. İ did spend some time working on Hunter jets. They have a breaking joint just aft of the trailing edge. Just a ring of big bolts that you need to remove to remove the engine.
All jolly good fun. Thanks for the info mate. Derek.

Re: Maybe a good idea, maybe not.

Posted: Thu Jan 01, 2009 2:21 pm
by tx river rat
put you a hook inside bottom of the hull and then fasten bulkheads aat top with bolts, sealed bulkheads will solve the leak problem.

Re: Maybe a good idea, maybe not.

Posted: Thu Jan 01, 2009 3:25 pm
by Kayak Jack
Derek, your thwarts and seats need to be a quick-disconnect mount. Because they will probably have to be removed for nesting.

In my canoe, I use a simple line from gunnel to gunnel for a thwart, as it's job it to hold tension, not compression. But, in your hull, I would use a wooden dowel, say, 3/8"-1/2" diameter. You just may encounter a situation where compression resistance is beneficial, and your hull will be more flexible than a mono-hull. Lash it at both ends, and unlash only one end for storage, letting the other end hinge.

Matt may well have some better ideas. If so, listen to what he says and discount my input.