Saturday, November 1, 2014

Skin On Frame Canoe

This post is not at all quilt related, but I thought many of you would find it interesting.  This past week my hubby Nolan was asked to participate in the PechaKucha Night being held at out local library.  If you haven't heard of PechaKucha before it is"the art of concise presentations".  Each presenter gets 20 images x 20 seconds to share.  Nolan's presentation was on his building of a skin on frame canoe. You will get to enjoy more than 20 photos, but I will turn things over to Nolan for the builder's perspective.



What is a Skin on Frame canoe?  It is a canoe built along the lines of the traditional "Eskimo kayak."  There is a framework of wood to make up the structure, mainly tied together instead of hard fasteners (ie. screws or bolts)  and then covered with a skin to keep the water out. The one I built is like a Prospector style for you canoe heads out there and is seen above beside my store bought Prospector 17 made out of Royalex.  The impetus for building a canoe came as I had convinced the family to come out on our girls first canoe camping trip.  I was one canoe short so - voila, an excuse to build one.


Traditionally skin on frame boats are built more by feel, one bends to the wood to the shape they want, forming it by eye and go from there.  I wanted to use a pattern of a canoe that has proven to have the attributes I desire so I adapted plans for a cedar strip canoe.  Above are the paper plans I bought from Bear Mountain Boats for the "Nomad 17".  The book "Building Skin on Frame Boats" by Robert Morris, is one resource that I have used that talks about building skin on frame boats.  So a melding of the two styles is what I used.  The book speaks mainly to building a "Greenland kayak" which was my first skin-on-frame build.  I was so impressed with the result that I wanted to try a canoe as well.


The picture above shows the "Strongback" which is a box beam made to be the length of the canoe, straight and flat.  The forms were cut from plywood using the plans referred to earlier.  A little care here in prep to ensure the forms are true to form and the canoe should come out like it was planned.  It is upside down here.  The form with the lines of holes is one stem form.  The holes are used too clamp a bent piece of wood to form the stem.  


I couldn't find an appropriate good looking model to stand with the steamer so Lori left me there.  My low-budget steam bender was an old piece of ABS pipe with an older kettle as a steam source.  Insert the wood strips in one end, add steam to the other with the kettle and cook the wood.  


Low budget steam generator.  The new fangled kettles have automatic shut offs that defeat the steaming purpose.  Found this one in a thrift store.  T-shirt tied around as an impromptu gasket.


These are the stems inside drying.  The strips were bent, cooled and glued together to make them a solid unit.  As it was still freezing outside at night I had to bring them inside to cure.


This shows one stem with some laminations bent and clamped into place to cool and set.  As the wood cools, the lignin softened by steaming sets again to hold the wood fibers in their new shape - mostly.


Above the "spines" of the canoes are bent and fastened to the forms.  The keel strip and gunwales give the longitudinal strength to the canoe and are at fixed location as per the plans.


Next the stringers are added.  These are about 3/4 of an inch square and are of regular red cedar deck boards.  Less weight and rot resistant.  These were spaced by eye to be evenly spaced and to make sweet stem shapes.


Above the stringers are zip-tied (not too traditional but easy) into place with the stems pegged, lashed and glued to the stringers.  The strap is used as a backing strap to bend the ribs after steaming.


Action shot - piece of wood for rib, hot from the steamer. Pieces are about 1/4" thick green ash and about 1 1/8 "wide.  Apply backing strap to keep the piece from cracking as it is bent. 


Finding a friend (ie. wife/daughter) smoothly bend the rib over the canoe as a form.  Smoothly not too fast to allow wood fibers to slip but before it cools too much.


Phew - it bent and didn't break.  This canoe build was good as far as little breakage in bending.  I realized the selection of wood is key for success.   Learned that the hard way with the earlier kayak builds.

Once bent we slipped it inside the stringers in its place to clamp in place as it cooled in its permanent shape.


Lots of clamps needed, beg borrow ...Limits how many ribs can be bent at one time before waiting for them to cool. 
Success - ribs bent - still married.  Only can have one boss for this, It is in my garage so I was allowed to be the boss....('nough said)

Child labour is encouraged under the guise of "life lessons in wood bending"  She might be able to use this insight somewhere in life...


Ribs bent into place with clamps holding until they are tied permanently using artificial sinew.  Artificial sinew is like heavy weight dental floss.  Nylon floss impregnated with wax.  It has replaced duck tape as my go to fix for all.


More child labour to spread the load so I didn't get a mutiny.  28 ribs in all and I must say I never had any real complaining, they were willing victims.


Ribs tied to stringers.  28 ribs x 11 stringers = 308 knots.  That took a few nights, a few near beers and was rather therapeutic.  Also good for developing callouses on ones little fingers.


All tied together, now the moment of truth as it comes off the forms.


So far so good, came off and looks canoe-like.


Now the ribs and stems need trimming.


Ribs all trimmed up,  Add the inwales to sandwich the ribs between them and the outwales.  Each rib is pegged into the inwales and outwales then lashed into place.  I used a heavier black tarred  nylon for durability as the gunwales get a fair bit of wear.


The decks were added to stiffen up the stems with some left over purple heart wood for flair  Floorboards lashed into place as well. 


In the spirit of the build, had to make our own seats as well.  Wood frames and laced with parachute cord like a snowshoe.  These are usually woven more tightly but the cord is so strong and this makes for a nice and cool comfotable set.


The seats were hung from the gunwales using wooden spacers and bolts.  Could be lashed to a stringer but I had more faith in this method. 


Skin stretched into place.  It is one piece of ballistic nylon bought from Spirit Line Kayaks.  Ballistic nylon is a specific weave that used to be used for flak jackets used by the military.  So its a tough weave with a weight similar to the cordura nylon cloth used for suitcases.


Stretch into place and then staple along the edges. 


Flip it upright and then I rolled a nylon cord into the upper edge and stapled again to add strength to the edge.


Nylon cord - Spreads any tension load across a larger area so the fibers don't pull apart under tension.


Another moment of faith, - trim off the excess of the stems to be sewn up.  No mistakes allowed here or will have to buy another piece of fabric.


Stems sewn up with welting cord to add structure to the seam.  Unwaxed dental floss as thread.


A finished stem, actually went very easily, I was surprised how easily.


Canoe built awaiting a coating of urethane to seal the fabric.


2 part urethane (available from Spirit Line Kayaks), mixes like 2 part epoxy.  Once mixed one has a limited amount of time to get it where it needs to be before it sets up.  More conscript labour.  Lori was the queen mixer.  The urethane has to be carded/squeegeed onto the fabric and into the weave of the cloth.   Only get one chance, fairly forgiving but cannot add any more later at it won't stick.  If one is a perfectionist this may drive them crazy - I'm not.  I can live with the odd ripple in the finish.


Keel rub strip added as well as an epoxy impregnated piece of rope to the stem to save them from wear.


In the spirit of the canoe trip and the impressive qualities of parachute cord girls made us all survival bracelets out of parachute cord.

The proof is in the pudding - it floats and survived a canoe trip none the worse for wear.


The Royalex canoe with Lori and Kyla on Mikanagan lake in Manitoba. This one was referred to as the "mom van" canoe.  Sturdy, and could carry more than we needed to bring.  Not super fast, but very reliable.


Kendra and I in the skin on frame Nomad on Lac Aimee - same trip. This was the racing canoe comparatively!


In the reeds awaiting portage on the Pineroot River.


Setting up camp on Lac Aimee making sure canoes are safe.









5 comments:

  1. Since seeing this in your garage at it's early stage, it is nice to see and hear the whole story from Nolan's perceptive. Hope you will make your canoe trips up north an annual event!

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  2. So cool. Thanks for sharing, Nolan. Your kayaks and canoe are definitely labours of love and the products of extreme patience.

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  3. Very cool. Thanks for sharing this. As a kid, we used a fiberglass river canoe my aunt and uncle had made themselves---you didn't want to scrape your legs in it, that's for sure, and it was very heavy. Nolan's method looks much better.

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  4. that was a fascinating build! Thanks for sharing!!! Now my husband wants to build a canoe, LOL. We have a 17' aluminum canoe that we NEVER use though, so I am sure we won't be building a canoe anytime soon :) Does look like fun though!

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  5. Looks very cool.How rigid is this type of construction? Does it flex at all?

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