My Merlin Rocket: September, 2014

The Rubbing Strakes (Continued)

Last month I fitted the forward and aft rubbing strake pieces on both starboard and port sides. Then, I scarfed the inner ends in preparation for the mid-section piece. I projected a tangent line off the gunwale to the rubbing strake and proceeded to shave and sand until a smooth flat scarf joint surface was achieved.

Next, I placed an 8 ft long x 120mm x 9mm rubbing strake piece against the starboard side gunwale. The curvature of the required rubbing strake piece becomes evident here. I placed the aft end of the rubbing strake piece against the end of the scarf of the aft piece and held it in place with a bar clamp over the side deck. Then, I bent the board around the gunwale and clamped the forward end the same way.

I left about 5mm of excess material over the deck on both ends. Then, I traced a pencil line on the rubbing strake right over deck line and under the gunwale.

Here I'm holding the rubbing strake piece against the side deck and the beginning of the forward piece scarf to test the fit.

Unfortunately, it will require 4 rubbing strake pieces to do each side since the rubbing strake has to be at least 50mm wide from the edge of the deck.

Had I measured that requirement sooner I would've cut longer aft pieces or cut a board about 180mm wide by 9' long for the mid-section.

Once the lines are traced, I moved the piece over a temporary workbench to measure the width of the piece I'll cut and make sure it is at least 60mm in width (50mm + 5mm extra on top + 5mm extra on the bottom).

Using my band saw I cut along about 5mm off the pencil lines. Noticeable is the banana shape of the mid-section rubbing strake.

Dry run to test the fit prior to applying an epoxy resin with colloidal silica mix. Again, I use 1" scrap strips of 4mm marine plywood to protect the deck from the bar clamps.

Front view of the clamping setup.

View of the clamping setup from underneath. Making sure the rubbing strakes are tightly held flat against the gunwale is critical to ensuring a tight joint with the top of the deck and the bottom of the gunwale.

Before fitting the rubbing strake permanently to the gunwale, I apply blue tape along the edge of the deck for protection.

Inside the boat, my cedar timber counter weight to offset the weight of the clamps while I'm working.

All clamps on deck!

Over the inner edge of the side deck, I place the scrap strips of plywood for protection.

And here is the view from down under from the rear.

This time the view is from the front.

Next, I followed the same method on the port side.

Another view of the port side from the front. The second time it goes a lot faster.

And the port side view from down under.

For the last piece on the starboard side I used again the 4" x 4" cedar timber over the forward deck to clamp the bar clamps from for the counter torque technique and hold the rubbing strake piece tightly against the top edge of the deck.