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Re: Sheer clamps
By:Rob Macks
Date: 12/24/2000, 1:04 pm
In Response To: Sheer clamps (Pete)

: I built a CLC with sheer clamps, and a Guillemot without them. Ted Moores
: recommends them in Kayakcraft. Any opinions on why they would be of any
: advantage on a stripper?

: Looks like they would be of some help when it comes time to marry the deck
: and hull, but I don't recall that being terribly difficult. Extra
: complexity, extra weight, extra time. What do you folks think?

Ted is a fine canoe builder and this is a canoe builder’s solution to a kayak issue. He has adapted canoe gunnels to a kayak.

There can be a problem with the interior sheer clamp if attention is not paid to proper sealing of all wood surfaces.

This wood for the sheer clamp is extra weight. Especially if hardwood is used. And all the screws used will add more weight!

I just read through Ted’s description of the sheer clamp and it is a LOT of work.

There is much more work with a sheer clamp than glassing the seam. With the sheer clamp you must: cut the sheer clamp wood, fit it into the stations ( as Ted does), seal the wood with three coats of epoxy, add fillets between the deck and sheer clamp (this is a lot of work!), glass over the fillets up onto the sheer clamp, fit the deck, pre-dill screw holes, screw down the deck

PLUS, Final joining of the deck to hull includes remove deck, install bulkheads foot braces, Make cradle to hold deck upside down (because glue joining deck at sheer clamp will run down the inside of the hull if you don’t) Adding glue to the sheer clamp screwing the deck down. Glue the rub edge over the sheer clamp screw heads. You use screws to hold the deck in place then you’ll put a piece of ash to cover the screw heads and seal the joint. This exterior wood strip and the screws to hold it in place adds considerable weight. Then you must counter sink the screw heads and fill the holes in the exterior rub edge. Trim the top flush with the deck, clean up glue drips an varnish with enough coats to waterproof.

If you want a beautiful 19th century kayak this is the way to go!

For my glassed joint between the deck and hull of my kayaks I bevel the interior edges of the deck and hull strips (on a tablesaw) before installing them. These bevels will create a back bevel at the joint of the deck and hull where only the very outside edge of the deck and hull will touch on the sheer line making the join very easy to fit and invisible.

When you’re ready to join the deck and hull, fit softwood blocks into the stem tips of your hull and epoxy in place. Apply thickened epoxy to the first 6” at the tip of the bow hull edge.

To join the deck , lay scrap strips on the hull to support the deck. Tape the deck the hull with 2” clear packing tape going around the deck and hull every 16”, aligning the edges as you go. As you approach the stern in taping the deck down add thickened resin to the stern tip of the hull edge. Apply strips of tape on the exterior seam to seal them since resin will want to leak out here.

It ‘s easy to reach the interior seam through the hatch openings and cockpit of the boat. Prop the boat on its side on slings with one seam facing the floor. Lay DRY 3” wide 6 oz. seam tape into the joint. straddle the joint with the tape and press it in place to conform to the angle of the joint of the deck and hull. Make a long reach brush from a 2” foam brush. Cut off the handle and trap the brush between two pieces of scrap strip and staple together. Then hot glue a 2 foot long wood stick handle onto the brush. With this you can easily reach into the stems. Mix 3 oz. of resin and reach into a stem and pour the resin on the seam tape and brush up to the bow with the long reach brush. Continue to brush 3 oz. batches of resin to the other stem until you have wet out the whole seam.
Gravity will pull the resin into the joint and fill the back bevel keeping the resin on the seam tape where you want it. Once one side has set, flip the boat and do the other side.

The exterior seams I glass with strips of glass I cut from my regular 6 oz. cloth. I don’t use the seam tape because I have found the finished edges trap air bubbles. The edges of the exterior seams are feathered and become invisible.

The shape of the glassed seam at the angled joint between the deck and hull will create strength on its own. Think of a piece of angle iron.

All the best,
Rob Macks

Messages In This Thread

Sheer clamps
Pete -- 12/24/2000, 1:10 am
Re: Sheer clamps/Shear Strips *Pic*
Grant Goltz -- 12/24/2000, 2:23 pm
Re: Sheer clamps/Shear Strips
Ron Eike -- 12/25/2000, 7:53 am
Re: Sheer clamps
Rob Macks -- 12/24/2000, 1:04 pm
Re: Sheer clamps
Tom Preska -- 12/24/2000, 9:37 am