Friday, May 30, 2008

Cutting Ribs to Shape

The bent ribs have been drying in the hull for a while and it was time to cut them down to size to prepare for fine tuning. This involved marked the ribs at the gunwhale with a pencil and then cutting them down with a coping saw. Initially I thought I could just saw horizontally along the sheerline and move from rib to rib. But this proved to be too ackward at this scale.

Trying to cut down ribs

Instead I carefully removed each rib and placed them face down on a table corner and then proceeded to cut them with the saw.

Cutting on the table

After each was done, it was layed into position around the previous one so that I ended up with two identical sets of ribs. The ones nearest the stems had to be cracked to fit into the tight V-shape of the hull at those locations, but this isn't unheard of.

Ribs organized for placement later

Interesting that when layed out on the table, they look quite uneven. Even though they're pretty raggedy, this is the best I could do and overall, I'm quite happy with the way the ribs turned out. Next I can lay out the sheathing and start placing the ribs into position...I'm getting near the end!

Wednesday, May 28, 2008

Gumming the Inside

With the ribs and sheathing all ready, the next step involved gumming the inside seams of the canoe with pine gum. The kit had provided some commercially prepared pine rosin (without dirt & debris) that could be melted and tempered directly without the need to strain out any impurities. Sources write about different gums (like Spruce, Tamarack, but never Balsam gum) being used in bark canoe building. The gum itself is too brittle if simply melted and applied so it must be tempered with some source of fat. Traditionally this involved highly saturated bear fat. Given that wasn't an option, the urban equivalent used was commercial Lard. After picking some up at the local grocer, I set up for the event.

Given the potential flammability of pine gum and the fact that it really ruins cookware, I prepared it outdoors with an extinguisher at hand and used some cans destined for the recycle bin. The heat source was a Magic Heat stove kit.

The Setup outside; Melting the rosin; Adding in Lard

Books mention that enough fat must be added to make the gum pliable, but not too much to make it runny or greasy. This means adding a small amount of fat (I used half tsp at a time) and evaluating the gum. One way is to stir with stick and monitor the strands of gum that drip off. A perfect mixture gives off a strand that can bend without cracking.

A more visual method that I preferred involved dipping a sample of test bark in the heated pitch, then quickly dipping it into cold water. The bark sample is then bent back on itself and the gum evaluated for pliability. If there is insufficient fat, it'll crack and if there's too much fat, it'll be greasy and drip off. My own batch needed just 2 tsp of lard and a few tests to get it right.

Dipping test bark in pitch; Dipping in Cold Water; Testing for cracking

Gumming the inside also meant sealing problem areas on the bark. In particular, there was one significant branch hole on the port side as well as minor holes on the bottom. To seal these, I gummed the area and placed scrap pieces of bark over the holes, and then applied more pitch over these to glue them in place. Made for a messy interior but they'll be covered with sheathing soon anyway.

The portside knothole; Scrap bark pieces for the holes; Sealed up

The largest use of the gum was to seal the lap stiches from gunwale to gunwale. The pics below show one end and one side of gore stitches sealed.

Sealed lap stitches; Sealed gore stitches

I ended up using about half my supply of pine rosin so far, which means I should have more than enough to seal the outside and stems. To make the gumming look neater on the outer hull, I'll probably use some masking tape on either side of the stitches when I get to that stage.

Tuesday, May 27, 2008

Temporary Paddle Sleeve

In order to protect the shafts of my paddles from the aluminum gunwales on my cheap canoe, I came up with a temporary solution that I decided to call a paddle sleeve (sounds more pleasant than a "shaft protector"). It's basically a piece of scrap leather that is loosely stitched with leather shoelace.

Wrapping wooden shafts with leather isn't a new idea, although I first got the idea from a product advertised on Tandy Leather's website as a Walking Stick Grip kit. The kit was simply some tooling leather with lacing to form a rough gripping area on wooden staffs. Famous Paddlemakers Shaw & Tenney use leather on their oars to protect the wood from the oar rings and another site run by Paul Gartside documents the details of how to finely stitch a leather piece onto an oar shaft as a permanent fixture.

For my purposes, I wanted a temporary solution that I could transfer relatively easily from paddle to paddle when I'm in the mood to change. Instead of the X-style cross lacing pattern commonly used on these products, I consulted Ian's Shoelace site and settled on the Double Helix method. Easy to lace and to tighten with one hand.

Scrap leather piece; Punching the lacing holes

Lacing up the paddle sleeve

I realize that many purists will say it's a sin to pry the paddle off the gunwales and shun any additions to the paddle shaft (like leather whipping etc.), but I don't understand the fuss. This temporary solution using otherwise scrap materials works for me and can be unlaced and transfered to another paddle when needed. While it may seem bulky, the leather stitching doesn't get in the way if you paddle with the seam facing towards the stern, as the leather wrap bears all the abrasion during the correction strokes.

The final product

Sunday, May 25, 2008

Poplar Spoon

While up north last weekend, I took some time one evening to carve out a spoon from some left-over wood stock. The blank had been cut last time I was at The Carpenter's Square workshop so this really wasn't a pure bushcraft spoon hewn out of a log with an axe. I ended up working on the poplar blank (3rd from the bottom) in the following pic.

Spoon blanks and quarter-scale paddle blanks

Anyway, I started on a simple shape with a deep bowl and made good progress carving away with my Mora knife and Frosts spoon knife. It was near sunset so I never took photos of the carving process, but once back in the city and after a thorough sanding, I was left with a decent spoon. With some minor pyrography along the rim and a coating of coconut oil, this one's good to go on the next paddling trip. I've found spoon carving a fun way to use some of the smaller scrap pieces left over from paddle-making.

Sanded & Decorated

Oiled Up

Friday, May 23, 2008

Bending the Ribs

Now for the part of the build that most look on with trepidation...the initial bending of the ribs. All the readings mention making extras because of the very real possibility of some ribs breaking. Gidmark's chapter on Algonquin builder Jocko Carle mentions that Jocko once broke 22 ribs while trying to make a canoe! Given the limited amount of stock provided by the kit I was really only able to make 26 quality ribs to just fit the boat. So there was little room for error.

The process started by soaking the ribs in warm water in the tub overnight. The pic shows two bundles of ribs being weighed down with full water bottles. I had previously layed out and numbered the ribs when I had carved them a while back. They were numbered starting on either side of the centre thwart moving towards the bow - so I had 2 sets of 13 ribs bundled and soaked. The hull was quickly cleared of debris and full-length pieces of temporary sheathing were placed on the bottom and the sides. These were held in place with some scraps that were loosely bent to form "temporary ribs".

Soaking ribstock; Empty clean hull; Temporary full-length sheathing

Bending ribs needs a steady supply of boiling water. A few weeks back while cleaning out the parents' storage room, I came across a single 1000W electric stovetop and quickly took it for this project. Setting it up on the table, I had a constant pot of water on the boil that I would use to soften the ribs (two at a time) and begin the bending process.

Soaking in boiling water; Easy bending; 1st center ribs in position

As I progressed, I started marking the underside of the ribs with red permanent ink to show the approximate bending points. These would be hidden from view anyway and marking with a pencil tends to score the softened cedar at this stage. For some of the sharper bends as the ribs get closer to the bow, I used the rounded handle of the awl as a form. Things progressed smoothly between the center and intermediate thwarts and there were no problems.

Bending around awl handle

As I got closer to the sharper ends however, I ended up cracking one rib, with three ribs that had "wrinkled" severly enough that I thought they would fully crack when dried. The good news was that by then, I had realized that the long ribstock pieces could be bent off centre so as to obtain another rib from the same stock. So despite losing 4 ribs, I was able to salvage them given my shortening supply.

Wrinkled rib (replaced later); All ribs loosely in

At this stage, the loosely held ribs need to be tightly pressured into position by means of a "binder". This binder is basically two pieces of long cedar (like rough gunwales) placed inside the boat that are forced apart and down with struts - effectively pushing the ribs against the contour of the hull. The force of the binder is strong enough to rip out the lashing in the thwarts so something is needed to offset this outward pressure. Many readings tell of builders nailing temporary cross-braces right into the gunwale, but after building this thing without any metal fasteners of any kind, that seems like sacrilege. Instead, I used some scraps to make braces that would fit across the hull and latch onto the gunwales with notches.

Carved cross braces; Braces & Binder pieces in position

I re-used the temporary thwarts that had been removed from the structure by this stage for struts to stretch out the binder and force some pressure to hold the ribs in position. Now that the bending of the ribs was done, I took the pot of boiling water to the bathroom, placed the canoe in the tub, and poured the hot water gently over the all the components in the inner hull. Then back at the table, I tightly pushed the binder down and squeezed in other bits of dowel or scrap cedar in spots to further push the binder against the ribs. When I was done, the hull had transformed from a flat bottomed structure to a slightly rounded bottom, tumblehomed sided shape. And for the first time, the hull is rigid and strong.

Final soaking; Closeup of binder; Binder and braces in position

Now I need to patiently wait 2-3 days for the whole structure to dry out after which I can cut the dried ribs to their proper height and begin the final stages of the build.

Drying out

Thursday, May 22, 2008

Making Cedar Sheathing

Another structural component of the canoe is the cedar sheathing that is layed down on the inside of the hull and ultimately sandwiched between the bark and the ribs. Its purpose is to protect the bark, add structural support, and minor waterproofing to the inner hull. In a full size model, the cedar sheathing is split down to ⅛" thick or less. Master builders do the splitting by hand. César Newashish demonstrates the process in César's Bark Canoe, splitting a huge board of cedar over and over again until he ends up with 5 ft long pieces that are paper thin - fascinating to watch.

In my case, I took the random length pieces of plank cedar provided in the kit and tried to split them in approximately ¼" wide pieces, although the natural splitting tendency of the wood dictated the ultimate sizes. These were then shaved with a block plane down to 1/16". Technically they should've been 1/32" to fit the scale, but they were too delicate at that thickness.

Sample piece of sheathing stock; Splitting into strips; Planing down

I ended up with a bunch of random length pieces that should cover the inner hull. The good news is that unlike the stock for carving the ribs, I've got plenty of sheath making material.

Pile of sheathing resting on the canoe

I haven't decided on the sheathing pattern yet. Algonquin and other central native groups tended to use short (4-5 ft long) sheathing and overlaped in groups to cover the inner hull. Others used longer pieces (7-8 ft) to cover the hull in halves. Either way, the sheathing will need to be cleaned up a bit before its final placement. But now that this is done, I can move on the the most exciting part of the build for me so far - bending the ribs. More info next post.

Tuesday, May 20, 2008

Stitching the laps and gores

Now that the gunwales and ends were done, all that remained in the seemingly endless stitching were the overlaps in the hull bark and the gores. Using the fresh roots collected and split earlier in the day, I started off working on the laps which would need a long piece of root to stitch all the way around.

At this stage, I moved to working on a table by the dock so that I could have quick access to the lake and soak the boat as needed. The ends were soaked and pegged into to position to create a bit of rocker. Then using a stitch outlined in John Lindman's articles on Canoe Building (Wilderness Ways v.6, Issues 2-4), I sewed all the way around from gunwale to gunwale. Basically the stitch calls for parallel set of holes with a single piece of root stitched horizontally on the outside and diagonally on the inside with the ends tucked under diagonal crossings.

Pegging the lapped bark into position; Outside stitch; Interior stitch

Working on the stitch meant meant constantly flipping the hull over and over. No problem on a 3-ft model but on a full scale canoe, this wouldn't be practical. I'd need to constantly be over and under the hull which would make stitching quite a chore. The solution would be to ensure a large enough piece of bark to at least cover the length of the hull.

Continuing the stitch under the hull

In the end the laps were tightly stitched to form a nice seam. Here are some shots of the completed lap seam.

The completed lap seams

After this was done, I could proceed to stitch up the gores. This stitch is basically the same as for the laps except they obviously didn't go all the way around the hull. Once one was done, I stitched the opposing gore.

Unstitched gores; A pair of stiched gores

By this time, I was quite tired of stitching and with the holiday weekend weather making a turn for the worse, I had come back home. Back on the city balcony I continued the gore stitching until I came to a problem. One of the gores had uneven, ripped bark and the stitching revealed a significant gap that I didn't think would seal with gumming. So I took a piece of scrap bark left over from the initial cleaning and cut it down to size to fit nicely between the inside stitches. When tightly pulled, this extra bark tightly seals the crack and will nicely serve as a suface for proper gumming.

Sealing a crack with extra bark re-inforcement

I realize that I've made the gore stitching a little wider than the scale dictates, but I was worried the bark may crack at the stitching holes so purposely left them a little farther apart. This will create wider gumming marks when the seams are sealed but I can live with that.

Stitched gores with fresh spruce root

With all the gores stitched, I've finally completed all the lashing! This has been the most time-consuming part so far, taking up at least as much time as all the other parts put together. The books say as much so I must be on pace with normal building times.

Newer Posts Older Posts Home Page