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Spray HPK – Joining the Deck to the Hull

Posted By Dan Caouette

The big day of joining the deck to the hull was almost at hand.  That would turn it into a kayak.  To make my life easier, before I did that I wanted to finish everything on the interior.  It’s easier to access the interior when the boat is split at the sheer instead of working through the cockpit and hatches.

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First thing was to roll a finish coat of epoxy on the interior.  I used to use varnish or paint but for the past few years I’ve switched to a single coat of UV stabilized epoxy, Entropy Resin Super Sap CLR/CLF in this case.  The epoxy has UV filters in it and provides plenty of protection to the cockpit and holds.  They generally don’t see a lot of UV exposure.  The cockpit will get a urethane clear coat during the painting stage.

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While I had the interior accessible I bonded the carbon pad eyes for the hatch tethers.  Now is also a good time to bond any cockpit hardware (like the foot brace rails or mounting studs).

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All bonding surfaces get cleaned and then roughened with 80-grit sandpaper.  The surfaces get coated with thickened epoxy and the deck is lowered onto the hull.

The extra-wide, rabbeted sheer strip combined with the deck makes a joint similar to a plastic Easter egg.  The deck will bond directly to the rabbet on the sheer strip, helping eliminating the need to fiberglass the inner joint.  It’s much easier and neater.  The lack of heavy fiberglass cloth at the joint negates the weight of the extra wood.  The outside of the joint will be taped like usual and feathered into the hull and deck.

For light-weight or race boats the Easter egg joint is more than adequate strength-wise.  On expedition or ocean play boats subject to higher stresses, I further reinforce the joint with a strip of glass over the joint in the cockpit.

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The joint is pulled together by hand and held with strips of masking tape.  The rabbet also makes the joint self-aligning.  There’s no need to force the sides together with ratchet straps.  Now’s a good time to clean the excess epoxy that will squeeze out of both the inside and outside of the joint.  A little squeeze-out is good.  That means that the joint is thoroughly coated with epoxy, the joint is fully bonded and there are no exposed wood.

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Inside the cockpit I smoothed out the joint with a bead of thickened epoxy.  You can also see how I’ve already bonded the foot brace hardware.

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After the epoxy had set on the joint I took care of the exterior portion.  I pulled the masking tape holding the deck to the hull while the epoxy set.  With the ROS and a longboard I sanded 2 – 3″ (50 – 75 mm) on both sides of the exterior joint and then laminated a single layer of bias-cut 4oz fiberglass.

A few fill coats to the joint later and the exterior is ready for final sanding, priming and paint: our next topic.

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One thought on “Spray HPK – Joining the Deck to the Hull

  1. Dan the last layer of epoxy guess you have to sand everything before the epoxy to stick well,
    when hull and deck are joined in no need to put fiberglass strip on the outside but I guess if a strip across the board?
    system easter egg is very good idea.

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