Stems, Keelson and Chines

Pinning the ribs

Each 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.

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Steaming the Ribs

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.

The rib is then quickly moved across to the kayak deck frame, slotted into the first mortice and then using a timber wrench bent up into an arch and gently pushed into the mortice on the opposite side.

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.

When the ribs have 'set' they will eventually all need to be removed and sanded before finally being pinned with an oak dowel into the mortices.

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Cutting Deck Beams and completing the deck frame

The deck beams are formed with tenons cut at 73 degrees to set the gunwales to the correct vertical angle.  The length is also marked from the gunwales locked into place with temporary formers to determine the required profile in plan.

Two arched deck beams are formed to provide some clearance for legs inside the kayak.  The width of the kayak has again come from 'my measurements' - hip width plus some clearance (so again, a real made to measure fit should be achieved).   I finally end up setting the temporary spreaders to give me a 21" wide kayak and some further shape forced into the bow and stern of the kayak.  Deck beams are then marked to match the final shape once the tenons are cut.  The width of the kayak will be at the wide end of the Greenland design (just like me!) but considerably narrower than most modern recreational kayak designs.
 

The tenons get locked into place with 3mm oak dowelling which I have cut for the job.  They also have a lashing underneath made in artificial sinew and on alternative deck beams to help maintain the 73 degree angle of the gunwales.

A further lashing brings together both the stern and bow ends and in doing so I get to tie my first 'Eskimo knot' of the project!

The bow and the stern are dowelled with 9mm oak dowels turned into trunnels with a softwood wedge driven into both ends.  The softwood will swell when it gets wet and the whole joint will tighten up further.  The wedge has to be carefully placed at right angles to the grain in the gunwales to prevent them splitting the frame when they swell. 

The trunnel and wedges are planed smooth to produce a 'clean' and secure fixing.  The whole frame has been formed into a strong and stable shape, exactly matching the shape and dimensions set up from the formers and with the absence of any glue.  The frame is designed in these traditional kayaks to be strong but also flex in the sea and absorb the force of waves without straining and breaking up.

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Preparing the Gunwales

So instead of boat plans and following the Christopher Cunningham book as my guide, I find myself sitting on a 8" x 2" plank, balanced in the middle over a batten and taking various measurements 'off myself'.  At least it should end up a truly custom fit.  With reference points to my heals, feet, 'sit bones', back etc. I transfer these measurements to the two gunwales.  The overall length of the kayak if meant to be three arm spans, (or 3 times my height).  This would take the kayak to 17'6", but looking at the length of my garage workshop, I opt for a straight 17'.  The balance point of the kayak is worked out slightly aft of midpoint to ensure good tracking in the water and using various 'measurement rules' the rest of the deck beams and the twenty four rib positions are marked out on the 75mm x 22mm yellow cedar.  

Time for morticing.  To start with I cut forty eight, blind 8mm mortices in the bottom of the gunwales.  I use my new mortice machine for this mounted on my workbench which I run along the length of the garage on wheels.  These will later receive the steamed ribs.

The next mortices are going to be more difficult as although through mortices, they need to be cut through the sides of the gunwales at exactly 73 degrees.  Once the gunwales are splayed outwards at the top, this angle will mean the deck beam joints are back on the horizontal.  To start with I think about making up a jig for the morticer.  I soon realise it will be easier by hand.  Again following the book, I make up a jig to get three holes bored through at the correct angle in all twenty two of this next lot of side mortices.  The jig works fine and I spend several hours squaring the mortices up by hand.

I have already cut the temporary middle and end plywood formers, so having first cut a bevel along the top edge I fit the gunwales to these and I have the very start of a kayak shape.  The width of the kayak at its widest point is determined by the width of your hips plus two fists (there are some optional variations on this, depending upon the characteristics one is looking for in the kayak).   For this initial set-up this is set at 23" but I decide to have another look at this before I finally commit myself as first impressions suggest this may be a little wide.   There is something really intriguing around making something as three dimensional as a boat using measurements determined by 'rules' and body shape, as opposed to a blue print and offsets.  Very different from my previous two home builds.  

The 73 degree angle which I seem to be working with in every stage of the build is already working well as it forces the gunwales up at both ends to a really eye catching sheer line.  This is further helped by the curve cut in the ends if the gunwales at both ends.  It has just moved from two 3 x 2's into the start of a kayak and the workshop has the pleasant smell of yellow cedar being worked.

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Time for another home built boat

So this time the project is a Greenland Skin on Frame Kayak following the guidance in Christopher Cunningham's book on the subject and plenty of other research over the internet.  My other boats have involved epoxy and detailed boat plans.  In contrast this time I will be working with trunnels, artificial sinew and no design plans.  This will be a new experience and one which I am looking forward to.

The only epoxy job in the entire build, scarfing planks together to get the length I need.

I am working with yellow cedar and plan to use green oak to form the many ribs of this kayak.  The dimensions really will be made to measure and they will all be calculated in the traditional way using Anthropometric measurements based on me!

I have already spent some time researching the technique and sourcing materials and a few additional tools.  It is strange how one thing can lead to another and having found a new really good weekly podcast, I came across the download on skin on frame, an interview which Dan does with Corey Freeman of skin boats.  Next thing I know I have all the non timber materials, coating, fabric and sinew etc. on route to England from the states.

My garage is now turned into a workshop and the timber has also arrived.  The yellow cedar releases a really nice smell as it is worked (much nicer than drying epoxy and better for me I guess).

I will be interested to hear from anyone else out there who has a similar project on the go.  Anyway, happy building and another boat in the making to add to the fleet.

In between all this I intend to get some winter sailing in and some kayaking (so I will include a few other pictures along the way)!

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Arctic Circle Sailing 2011 - Norway

Just back from a fantastic sailing trip up in the Arctic Circle in northern Norway. Here are a few of the photos from the trip sailing on 'Velvet Lady' (a 55' Oyster) from Bod� around the Lofoten Island area.




At this time of year there is 24 hour sunshine, so providing the weather is right it's great for both sailing and photography.

These cod heads appeared to be hung up to dry in every little harbour we entered, sometimes on a truly commercial scale.

Peace and quiet!

Above - a slightly more traditional build in the spirit of this photo blog.

Colleen having a 'cold moment' in the arctic (which is allowed I think if you have come straight from Texas).

To me these big skies just lend themselves to b&w (above Bod� and below a Henningsvaer landscape).

'Texas John'

Joyce and myself fly the flag.

For a short video of the trip by all means have a look at http://www.youtube.com/watch?v=MxBqAMZI1zY to enjoy some more Arctic Circle sailing.

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