Build a Greenland kayak part 6

In part 5 of the Greenland kayak construction Instructable you installed the ribs. In this instructable you will lash the keelson and the hull stringers to the ribs and also add deck stringers and drill holes for the deck lines. The frame will be completed. And you will be making a coaming although you won't install it until after the skin is on the boat.

Step 1: Materials

2 hull stringers 3/4 x 1 inch in cross section, 16 foot long.
Deck stringers 3/8 x 1-1/2 inch in cross section, 8 foot total.
1/4 inch dowels
Lashing twine - nylon mason's line

Step 2: Tools

Drill and 3/16th inch drill bit for lashing holes
15/64 inch drill bit for drilling doweling holes
hammer for pounding dowels

Step 3: Drill lashing holes in the keelson

Drill a 3/16 inch lashing hole in the keelson wherever the keelson intersects a rib.

Step 4: Center the keelson

Measure the distance from the keelson to the gunwales in a few places to make sure that the keelson is centered. Then go to the end of the boat and sight down the keelson to make sure it is straight.

Step 5: Lash the keelson to the ribs

Lash the keelson to the ribs with the nylon mason twine. Cut a piece of twine the length of the boat.
Tie off the line at the bow and start lashing in the direction of the cockpit. You will get somewhere in the vicinity of the cockpit. Clamp off the loose end of lashing twine.
Cut another piece of lashing twine the length of the boat. This time start lashing at the stern. Lash in the direction of the cockpit. Tie the two loose ends of the lashing together where ever they meet.

Step 6: Cut the hull stringers

Hull stringers are 3/4 x 1 inch in cross section and 16 foot long.
16 feet is longer than you need, but you will be trimming them to the exact length that your boat requires.

Step 7: Position the hull stringers on the ribs

The function of the hull stringers is to hold the skin away from the ribs at the sides. The keelson holds the skin off the ribs in the middle.
Hull stringers should run roughly parallel to the bottoms of the gunwales getting about an inch closer at the ends.

Step 8: Cut hull stringers to length

Trim the hull stringers so they overlap the stem and stern boards by about two inches.

Step 9: Shape ends of the hull stringers

As the stringers twist around the hull they end up at about a 45 degree angle with the vertical. Shape the inside edge of the stringers where they intersect the stem and stern boards so they will lie flat against them.

Step 10: Drill the hull stringers

Drill a 3/16 inch lashing hole in the stringer at every rib to stringer intersection.

Step 11: Lash the hull stringers to the ribs

Lash the hull stringers to the ribs using the same lashing pattern you used for the keelson.
If you have any gaps between the stringers and the ribs that are greater than 1/4 inch, add a shim between the stringer and the rib.
When you're done, double check that the keelson is centered and that the hull stringers are equidistant from the keelson to either side. Although the keelson and stringers are lashed, you can move them around some if you are persistent.

Step 12: Lash the hull stringer ends

Lash the hull stringer ends together so they are in contact with the stem and stern boards.

Step 13: Install the rear deck stringers

Cut rear deck stringers to span from deck beam 7, the backbrace, to deck beam 8. Position the deck stringers so they are parallel to each other and about 8 inches apart. Dowel the deck stringers to the deck beams using 1/4 inch dowels.

Step 14: Install the forward deck stringers

Cut the forward deck stringer to span from deck beam 6, the knee brace to deck beam 4. Position the deck stringers so they are about 4 to 6 inches in from the gunwales. Dowel them to the deck beams using 1/4 inch dowels

Step 15: Install breasthooks

At both ends off the boat where the tops of the gunwales intersect the stem and stern pieces, there will be something of a gap. Breasthooks are small pices of wood doweled on top of the gunwales that bridge the gap and make for a smooth transition of the gunwales into the stem and stern boards.

Step 16: Drill holes for your deck lines

You won't be installing the deck lines until after you have put the skin on your boat, but it is best to drill the holes now so the sawdust from drilling doesn't end up inside the hull. Besides, it is easier to measure the position of the holes before the skin is in place.
Drill two holes in the gunwales 4-1/2 inches apart and six inches forward of deck beam number six.
Holes start at the outside edge of the gunwale and are drilled downward at a 45 degree angle. See the picture below for how this looks.
Drill two more sets of holes spaced 4-1/2 inches apart and six inches back of deck beam number 7.
Drill another pair of holes near the bow and another near the stern. Drill them at the point where gunwale separation is about 6 inches.

Step 17: Add a pulley for air bags

Your kayak should have airbags for floatation. Getting an airbag into the bow of your boat is difficult so it is handy to have a rope and pulley to help you pull the bag forward.

Step 18: Varnish the frame

Varnish the frame with your favorite sealant. I favor exterior polyurethane varnish.

Step 19: Make a cockpit coaming bending form

You won't need the cockpit coaming until the end of the skin sewing session, but it's a good idea to start it ahead of time.
The bending form should be an oval hoop of 3/4 inch plywood. The rim of the hoop should be 2-1/2 inches wide.
Length of the form should be the distance between deck beams 6 and 7 plus 1 inch. The width of the form should be somewhere between the width of your hips plus 1 inch and the width of the kayak minus 2 inches. For a kayak with a 21 inch beam, 16 to 18 inches is a good width for the coaming

Step 20: Cut and taper the coaming blank

The coaming blank should be 12 inches longer than the circumference of your bending form. It should be 1/4 inch thick by 1-1/2 inches wide in cross section. Taper the last 12 inches on each end down to 1/16th inch thickness. This will make for a smooth overlap.
Soak the blank in water for 3 days before bending.
Also cut a coaming rim 1/4 inch thick by 1/2 inch wide and 2 inches longer than the coaming blank. Taper the last 12 inches on each end as you did with the coaming blank

Step 21: Bend the coaming

When the coaming is done soaking, clamp one end to the back center of the bending form. Run hot water over a bit of the coaming blank at a time. Water should be too hot to hold your hand under. When the wood is hot, after about 2 minutes, bend that section around the form and clamp it. Then heat the next section, bend it until you are all the way around the form with the tapered ends overlapping at the back end of the form.
Lash the coaming ends together at the end so they don't spring apart.

Step 22: Bend the coaming rim

Using the coaming as a bending form, bend the rim around the top edge of the coaming. Position the overlaps of the rim ends at the left side of the coaming.
When the coaming rim and coaming are dry, dowel the rim to the coaming every two inches using barbecue skewer sized dowels.
Drill 3/16 inch lashing holes in the coaming spaced 1-1/2 inches apart and halfway between the bottom of the rim and the bottom of the coaming. You will be using these holes to lash the coaming to the skin.

Step 23: You're done with the frame

You're done with the frame!
Admire its beauty. It's almost a shame to cover it with skin which will be the next step.

Comments

[cephastaphile]

What do you recommend for a seat? As drawn it looks like the paddler will be sitting on the ribs

[nativewater]

There's a bunch of seats featured on my blog here.
http://skinboatjournal.blogspot.com/2012/07/kayak-seats.html
hope that helps. Thicker foam is more comfortable but raises your center of gravity. half inch to three quarter inch foam is what I prefer.

[movieman1500]

 I was wondering Do I remove the spacers that the keelson rested on once the Stem & Stern boards are on? 

[GorillazMiko]

Yay, part 6!! :-)