Sunday, 9 June 2013
Wednesday, 27 March 2013
I'm using 'ballistic nylon' to skin the frame and then will coat with a urethane two pack to waterproof the skin. It's cold in the UK at present and until the gas heater goes on in my garage workshop, the temperature in there just sits at 4 degrees Celsius. I am hoping this can be used to my advantage as the skin will shrink more (as it is nylon) as the temperature rises, so I am hoping this will result in a tight skin around the frame in most conditions I'm going to be out in.
So far I am pleased with the result and have followed the process below.
To me the symmetry of the frame just looks so good and even artistic in a very practical and traditional sense.
This was a new process for me and having put so much work into the framing I needed some reassurance and a quick confidence booster before I launched into sewing a 'bag' around my nice yellow pine frame architecture. So I emailed Corey Freeman of Skinboats, thinking I would get a reply sometime in the next 24 hours. To my surprise Corey got back to me almost instantly and suggested we talked via Skype. I 'dialled' him up (and felt slightly guilty when he reminded me it was 05:00 hours with him!). Corey talked me through the process and later that morning (last weekend) I spread the cloth out across the boat.
So this is how it went:
Drape the cloth lengthwise centred over the keelson.
Sew a pocket on one end (all the sewing is done using artificial sinew and sail-makers needles). At the stern of the kayak brace your foot on an appropriate deck beam and pull (and mark) the position for the second pocket. Slip the first off and pull the material along to sew the second pocket. Put the first back into position and then for the final time pull as hard as you can to get the second pocked over the stern.
Next turn the kayak over and start gathering up all the waste cloth at the top. Corey explains the process in some detail on his site so I won't try and replicate here. In summary a line of stitching is made along the centre of the deck spaced apart on both sides of the material. By bringing the stitching together the mechanical advantage of the thread stretches the material into place. Off course too much gap between the two tread lines and one ends up with a gap and too little and the material remains slack.
So far so good!
The waste material is then cut off (using a hot knife to seal the nylon) and allowing enough left to fold over and form a seam.
I'm getting old by this stage and need to put my glasses on for the second 17' of close stitching!
Both the bow and stern are tidied up with a cross stitch around the rolled material.
Finally the frame is sewn into place. The strap is to bend it down and once the skin is laced to the coaming, the wood will spring up and tighten the cloth around the cockpit area of the deck.
Again the cloth is trimmed with the hot knife around the inside of the cockpit.
Before lacing, the material is positioned in place all around the inside of the coaming with spring clamps.
A kayak finally emerges from a cloth bag!
Sunday, 17 March 2013
Finally the frame is complete and the next stage will be to apply the skin
The cockpit (1" wider than me!) is formed around the mould with steam bent green oak.
The Masik is laminated in yellow pine strips to provide the strength necessary and with birds mouth joint cut to fit the frame.
Taking the measurements and shape of the Masik to fit my knees for effective bracing.
The stem plates are pegged with oak dowels set in at opposing angles to lock the plates into place without the need for any glues - mechanical and traditional!
Tuesday, 5 February 2013
Pinning the ribsEach of the ribs is pinned in place with an oak dowel drilled through a blind hole in the gunwale.
Forming the stem plates
The stems are shaped out of 25mm thick timber (in this case yellow pine).
The first fixing to the gunwales is by an 'V', 'Y' lashing in artificial sinew. The final part of the lashing turns the 'V' shape into a 'Y' (above) and adds considerable force into the lashing to bind the stem both vertically down and back into the gunwale horizontally.
Keelson and Chines
The Keelson is then attached to the stem plates at both ends, and pinned in place (below) with oak dowels at opposing angles to lock the two pieces of timber together. Apart from scarfing the gunwale timber together originally to get 17' lengths, no glue is being used in this project, (just dry dowels, and artificial sinew!). I am amazed at just how robust the construction is as the various components come together. The traditional build technique described so well in the Chris Cunningham book is designed to be strong, but also 'give' and flex to the pressure of waves.
The Keelson and two Chines are held in place with a running square lashing in sinew. The lashing crossed itself before continuing to the next rib and in doing so puts pressure into the binding.
The two chines are carefully positioned to get equal and maximum clearance away from both the bottom and the side of the ribs. If the skin touches the ribs with the water pressure the kayak will quickly develop the 'hungry dog' appearance with rib bulges - not very ship shape!
The lines (above) indicate the path of the eventual skin.
Turned over and ready to continue with the deck.
Sunday, 6 January 2013
The oak used here is 'green' (not seasoned) and the high moisture content will help achieving the tight curves required for the kayak. The steaming process will convert some of the moisture to steam and the ribs will end up considerably drier (and more 'seasoned') once it has been 'cooked' and then bent into it's new shape.
The video below shows the process of steaming and fitting the ribs.
This has to be quite a fast process as the ribs quickly cool and 'set' once removed from the steam box. Time to move quickly and put some gloves on as the oak comes out scalding hot.
The length gauge (above) has been made to mark the ribs to length and ensure an even transition between the deeper bow and much shallower stern.
Once the ribs are cut to length the ends are thinned. By doing this the ribs take up a much shallower arch across the bottom (centre of the curve) and then a sharper radius as they form the sides of the kayak and run into the mortice.
The Steam Box (made with 50mm silver backed insulation foam, duct tape and a wallpaper stripper). It will last for this job!
Each end of the hot oak is first bent around a former to make the grain more flexible. A leather strap supports the timber while bending at the back.
About one in four ribs fail and split at the critical stage. Nothing else to do here other than start again and cut a new rib to length and thin the ends down. It is difficult to make spares in advance as it is impossible to know which ribs will fail during the bending process and they are all different lengths.
As soon as the rib is fitted into the frame and while it is is still hot and reasonably flexible (which is only minutes), it is important to sight along the kayak and adjust the profile of the rib so it is symmetrical and running fair with the others.
Slowly the whole rib cage of the kayak comes together.