Cockpit coaming

Well, this took a while.  I didn't have a piece long enough to to the coaming in one go, so I used the strips I cut (way back in January!), scarfed the ends so I could join them, wrapped them around a form, and epoxied them together.

The first step was to make the form.  I had the measurements from the last time I did a sit-test on the frame, so first I made a paper pattern.  This was made easy by using a piece of my wife's dress-pattern paper that has a 1 inch grid on it.

 

I needed a way to make clean curves.  Luckily I had a test rib that had just the right sharp curves and an extra rib blank that bent nicely for gentle curves.  I did one side and then folded it in half and cut both sides together.  (Then realized I'd forgotten to show the marking process and staged these pix)

   

Transferring to plywood was easy.  So was cutting it out on the band saw.



Finally I drew a line 1 1/2 inches in from the edge and used a hole saw in my drill to make places to put clamps all around the edge.  I don't scuba-dive any more so my dive weights have migrated to the work shop.  A dive weight worked nicely to keep the plywood from spinning around when the hole saw caught.

I needed a nice smooth wedge on both ends of each strip so I could scarf them together.

 

This simple jig with a wedge at the right angle and a bit of scrap to support the strip let me use the jointer to trim the angle.  Biggest problem was figuring out how to hold the jig together while doing the trimming.  Look at that nice sloped cut - and all of them came out at precisely the same angle!



The copper pan I used for the ribs was too short, so I hot-glued a foam trough and lined it with plastic. The first step was to soak the strips overnight.


Then dump the cold water out.  I made the end removable specifically so the trough can be emptied.

 

I boiled up a big pot of water on the kitchen stove, poured it in the trough, covered and let steep for 5 min. With the cover off you can see the steam rising.  Another convenient dive weight holds the strips under water. Note that the plastic both made it water-tight and kept the hot water from melting the hot-glue.



Then I put on some gloves and used pretty much every clamp I owned wrapping the strips around the form.

After letting the strips sit for a couple of days, I took the clamps off, put a strip of waxed paper around the form, and had a horrible time epoxying them all together.  My fault - I had a hard time finding waterproof clear epoxy in medium sized containers.  I didn't want to buy either little box-store two-part syringes (would have needed a stack of them) or quart cans that would have been mostly wasted.  Finally found some medium sized bottles but skipped over the fact that they were 5 minute epoxy.  It harded faster than I could get everything clamped together.



That got the tall part of the coaming done (here partly trimmed up).  Now I needed to do the outside rim that the spray skirt will hook over.  I just happened to have several left over rib blanks that are the perfect size.  (I had made extra 'cause I expected some to break while bending - but none did!)



They are too small for the jig so I used my plane to make nice wedge-shaped ends for scarfing.

 

Another round of heating, bending, letting sit, gluing and I'm ready to do the final shaping.

 

Smooth up the top and bottom with the plane and round the edges with the spoke-shave.



Finish up with scraper, file, and sand-paper.  I guess it's not bad for my first laminating job.  I could wish for better but I'm not going to do it over.



It sits perfectly on the edges of the deck beams.

The final two frame pieces are the the two deck stringers (the two pieces down the middle on top). Then a some finishing work and lash the whole thing together!

Thigh Braces

Aleutian kayaks are high-volume cruising boats.  This means that you've got more leg room and can move around a bit.  However, as a Greenland kayaker, I expect to be able to press my thighs against the underside of the deck and have positive contact (be "locked in") for good control when rolling.

I don't know how easy it will be to roll this baidarka, but I am certain that if I am flopping around loosely inside, it's going to be near impossible.  Which I don't like.

The solution is simple - thigh braces.  On a fiberglass sea kayak these would be molded in as the forward part of the "keyhole" cockpit.  In my case, since I had to replace the deck beam in front of the cockpit when I moved it, I designed the new beam to have supports to take the braces.



This is what they look like all finished.  Now let's see how I get here.

I already have convenient mortises in the gunwales, left over from the deck beam I removed.

The braces should be thin and strong.  I just happen to have some scraps of oak kicking around...

  

The bit of oak just needs some work.

  

And there we go, two lovely boards of just the right size.



Then some creative sketching and cutting on the band saw.

I need to create a socket on the underside of the deck beam to take the forward end of the thigh brace. This is why I've haven't pinned the beam in place yet.

 

I want the brace to lock into the deck beam so this calls for some careful carving of the underside of the deck beam.

 

Then the deck beam has to be cut at just the right angles in just the right place.  Catch-22 - I can't accurately mark it until it's finished and in place...  So cut a bit large, test fit, trim, test, shave with the chisel, test...



And it fits perfectly!  Well, the deck-beam mortise is horizontal and the brace is slanted, so that's not as pretty as it could be.  If I do another one someday...

Next up - bending the cockpit coaming!

Cockpit deck beams

Moving the cockpit forward means I have to redo the two deck beams that form the front and back of the cockpit, I've already diverged from Brink's plans somewhat.  Let's customize this a bit further.

The deck beam I took out was a bit fragile - it broke when I was taking it out. It was under a reasonably amount of stress, but still, I want to lean back with confidence.  So I will make the backrest more robust.

More interesting though, modern sea kayaks have thigh braces so you can lock yourself to the boat for control when you roll.  Baidarkas are high inside and there's no good leverage for rolling.  I have those unused mortises in the gunwales right in the middle of the cockpit side, where a thigh brace would start.  I could shape the cockpit-front deck beam with places to connect the front end of the brace.  Let's make the forward deck beam "brace-ready"!

The old deck beams were made for 2x4 lumber, but these needed to be heavier so I bought a lovely cedar 2x6.



The lines are a bit faint in the photo, but you can see that the center section is the critical width needed to slide my legs in (as measured when I put the boat on the floor and measured for fit!).  The side pillar sections will anchor the thigh braces.



Yay for narrow band-saw blades.  This would have taken forever by hand!



The plane made short work of the saw marks on the outside and the spokeshave cleaned up the inside, followed by rounding the edges with sandpaper.

The tenons are interesting to cut because the sides of the boat narrow toward the ends so the beams aren't cut square across.



The first thing is to use a sliding T-bevel to get that angle.

  

But how to hold the square against the wood when I've cut it away?  Luckily I have a piece that neatly fills that hole!

   

The next trick is to very carefully cut on the line - WITHOUT cutting down into the tenon.  A nice hack is to put a piece of wood on the far side at the height of the line.  Then I can watch how close I am on this side and cut down till it touches the block of wood on the far side.  Voila!  Perfect cut!  Note that the tenon itself I could cut on the band saw.

  

A quick floor test - the width of the arched space is perfect for sliding my legs in (with room for clothing) and the brace supports are at the right height for bracing!  However, the edge of the underside of the curve was a bit sharp against my shins sliding in.  Need to angle the underside of the curve up a bit.









Propping the beam up on piece of wood holds it at an angle so that the bandsaw cut is at just the right slope to make sliding under the curve comfortable.



There we are!  The cockpit beams are in place!  Next up, thigh braces and cockpit coaming.

Moving the cockpit deck beams

The holidays and the start of skiing season put a huge dent in my boat-building time.  I've been getting little bits done here and there however - my current completion target is February.  (Frustratingly enough, we're having an unusual January thaw and the local rivers are clear - if I'd finished up already, I could be paddling now!).

So, the float test indicated that the cockpit needed to move.  But not all the way to the next space between deck beams, sigh.  That means taking the beam at the front of the cockpit out and putting in two new ones half-way between the existing ones.

Of course, since I pegged the beam, the first step is to pull the pegs.



Simple enough - drill a hole in the center of the center of the peg, twist a screw into the hole, and use vice-grips to work the peg out.  The gunwales are flexible and spread just enough to get the deck beam tenon out.

Now I have one last chance to recheck the dimensions of the cockpit.  I put the boat on the floor and do another mock-up of the position of the front and back of the cockpit.



The plank is at the height of the back of the cockpit (where I will sit when sliding in).  The underside of the gray bar is at the height of the underside of the forward deck beam.  Yes, I can slide in, even with shoes on.

The vertical 4x4s are the width I need for my hips (including a bit of space for clothes).  This gives me final positions for the deck beams and it gives me the coaming dimensions both forward-back and side-to-side.



Now that I am sure where the new deck beams will go, it's time to cut new mortises.  But the boat is too long for where the bench was - so I had to get the mover's dolly to slide it down far enough that the mortise positions are on the bench.



Hmm, last time I put guides on both sides of my router so it would cut in just the right place.  But there are ribs on one side now.



So, a block on only one side, exactly 1/2 inch from the cutter.  And I'll have to be very careful to hold the guide against the gunwale!!!



A quick test - yes, perfect.  The ruler is at the 2nd test hole.  The closer hole was my first try - I didn't hold the guide tight against the edge and the router wandered, making a wavy slot.  Y'know, with software you can make a back-up copy before making tricky changes.  If I screw this up, the whole boat's toast.  No pressure.



The clamps set the limits of the hole.  I've roughed out the first deck beam to check the hole width.



Here goes!



The last step is squaring the ends of the mortise with chisels.  One end done, one to go.

I cut the mortises on one side and then went to turn the boat around.  Hmm, now that the bow and stern are attached, if I poke the bow into the bottom corner of the basement  and tip the boat at an angle I can just swing the stern just past the lally column where it holds up the ceiling.  If the boat was an inch longer I'd have had to trim the bill off the duck on the bow!

The next step will be to make the two replacement deck beams and lash everything in place.

In the mean time, I've started on the cockpit coaming.  It will be 1 1/2 inches high and half an inch thick.  I want to make it out of that nice green oak, but I need more than 12 feet to wrap around my 2 foot cockpit (circumference of a circle is pi * diameter - this is oblong so will be a bit less, but I need extra to overlap for the joint).  The log is only 5 feet long so I'm going to build the coaming up from multiple 1/4 inch strips.

I've used up the oak I cut for the ribs, so I need a new slab.  Luckily we had a warm spell and the snow melted off.



Cutting straight lines by eye is tricky.  If I were going to cut many more slabs I can see the advantages of getting a chain-saw mill.  I'd need a longer chain saw though - this is just a 1/4 pie slice of the log!



The jointer is really handy.  I used it to squared up one edge of the rough board,  Then took the board to the band saw and trimmed it to six inches wide (the width of the jointer blade).  Then back to the jointer to get a flat side.

Next, a bunch of passes through the planer made it into a pretty 1 1/2 inch thick board!  Have to admit, the jointer and planer are so much faster and easier than a hand plane - and produce a gorgeous square flat result.



Next was to cut four 1/4 inch strips.  The carbide blade on my table saw has lasted for more than 20 years - but cutting through the 1 1/2 inch green oak did it in.


The dull blade heated up and started to burn as it cut.  Even with two windows open and two fans running the basement filled with smoke (setting off the smoke alarm).  I guess it's time to replace the blade!

Next step on the coaming will be to make scarf joints to connect the ends of the strips, to cut an oval plywood form to shape the coaming around, and glue it up.

It's getting to where I can see the end of this project!