Skin-on-Frame microBootlegger Sport - Lashing the Frame


Hi, I'm Nick Schade at Guillemot Kayaks. In this fifth episode of making the skin on frame I am lashing the stringers to the frames.

A few of the frame pieces need to be assembled. Here the stern stem frame is fitted to the last sectional frame.

I use a waxed nylon floss called artificial sinew which is an untwisted thread that has a thin cross section and holds a knot well.

The sinew is tied to the part and then threaded at least 3 times through each of the holes and pulled tight after every pass. The wax helps hold it tight after pulling. 

I tie a couple knots around the bundled sinew to secure the ends.

The assembled frames are clamped back to the risers to hold them in their approximate location.

At this point I don't sweat the height, it is enough to just get their lengthwise spacing established.

The frames include some longitudinals for mounting the foot braces. I'm inserting some stainless steel t-knots so the foot braces can be bolted in place. I whack them in with a hammer to set the spikes.

It is easier to mount the braces now while the bolt holes are easily accessible.

These rails are assembled to adjacent frames in the same way I lashed together the stems.

The final assembly are the frames around the seat which include rails to eventually secure a backrest.

The wide main stringers can now be placed. These run perfectly horizontal and serve to define the height of all the forms. I hold them in place with a few temporary zip ties.

 The ends of the main stringers will be lashed into a hole in the end frame. 

A figure eight knot in the end of the sinew serves as a stopper. I thread the sinew through a couple hole and then tie the knotted end around long end with an over hand knot.

When I pull this loop tight, the overhand knot works its way up the sinew until it snugs up against the stopper knot.

The goal is to lace the sinew through the holes enough times that the parts are securely held together. Just one loop is usually not enough, but as you pull more loops through the holes, it acts like a block and tackle, providing more and more mechanical advantage until the parts are tight.

I like to get at least three passes between each hole.

This lashing was doing a fine job of pulling the stringer in from either side, but pulling the sinew tighter had the tendency to push the end form to the right. I needed some lashing to pull the stem back in.

The addition of a small hole through both stringers allowed me to get tension to keep the stem snug against the ends of the stringers.

After lashing both ends, I brought in the keel stringer.

Using holes through the keel avoids creating lumps along the bottom which may cause abrasion. I situated these holes so the lashing pulls the keel tightly into the hook on the stem.

After securing the bow, I lashed in a few of the frames along the length before moving to the stern.

Learning from the bow, I started with some lashings to hold the stringers together, then went directly to a pattern that pulled the frame tightly against the ends of the stringers.

Shooting holes in on either side of each frame did a good job of pulling the keel tightly into the slot. While the sinew is quite thin it would leave a bump if it passed over the keel. Because the bottom is the mostly likely point for the kayak to hit stuff, avoiding the bump should reduce abrasion.

Getting all the frames lashed to the main stringers and the keel starts to lock the shape in place. Later bending in of the additional stringers will add some force that may try to curve the frame. Hogging, where the ends of a boat droop down is common with skin on frame kayaks. Lashing these frames now should avoid hogging later.

But once these three stringers are secured, I could start right in with the rest.

I didn't bother lacing the sinew through holes in any stringer beyond the keel because I figured any bumps in the finished surface elsewhere were not a big deal.

There are a lot of lashings needed, but once you get into the flow of it, they don't take long.

With these side stringers, I'm just trying to get the end tucked in tight to the stem frame.

The chine stringer runs from the stern up to the keel just short of the bow, then a secondary stringer extends from the bow frame to about half way back where it blends in with the chine.

I need to lash the forward end of the chine stringer into the keel stringer. The gradual taper makes it tricky as the lashing wants to slip forward. Since the spacing is closer up forward, this loosens up the lashings.

I originally just tried wrapping the sinew tightly around the stringers from the narrower end back. But the wraps just slid down the taper. I solved this problem by drilling a hole through all the stringers and starting my wraps there. This prevented slippage and eliminated the bumps along the keel.

With the bottom stringers all installed, I flipped the frame over, and started with the foredeck stringer.

Like the keel, I positioned the holes so the lashing pulls the stringer in tightly against the stem notch.

I then thread some sinew through the hole and tie a figure eight knot as a stopper.

A figure eight has the end wrap over the sinew then circle around behind then the end goes down through the loop.

The overhand knot loops around other leg, down under the sinew and down through the loop.

When you pull it all tight the overhand knot slides up to the stopper knot and then pulls the loop snug against the stopper.

By forming a V shape with the lashing I create the ability to pull it even tighter when I'm done.

The last pass before the knot comes out at the top of the V. I thread the sinew under the lashing and make a couple wraps around the needle.

When I pull this snug, it closes up the bottom of the V, cinching all the threads even tighter.

Another pass under the lashing and wraps around the needles lock this knot in place.

As added insurance, I add a figure eight stopper knot on the end. I use the tip of the needle to pull it as close to the lashing as possible.

These lashings are really robust. Since the lightweight frame is bound to flex a little bit any stiffly glued connection between the stringers and the frame would likely crack and break. The sinew lashing is flexible and resilient allowing movement without breaking.

Gluing the low surface area joint would be problematic. Most waterproof adheasives, such as epoxy are stiff and relatively brittle. The edge grain of the plywood frames forms weak joints. As a result this lashing will be substantially more durable than glue.

The aft end of the fore deck stringer gets lashed to the forward cockpit frame and then the coaming ring will be lashed to it.

I ended up shooting a few extra holes in the coaming ring to provide lashing point between the ring and the frames. The ring lies on top of the frames and gets lashed down directly to the frames.

The front of the coaming ring is lashed directly to the ends of the stringers, tying the whole system together as one unit.

This whole process of lashing together the frame is kind of fun. While there are quite a few lashing point, it is nothing compared to wiring together a stitch and glue kayak or fitting strips on a strip built design.

It is quiet and relaxing and provides quick, satisfying results. 

I really like the look of the completed frame. It is kind of a shame to hide it all under the skin, but that is what I'll be showing in the next video.

Feel free to post any questions to the comments area. I'll get to them as soon as I can.  

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Until next time, thanks for watching and happy paddling.