The Naiad Voyages

Mark Austen

2016.09.20 - Rubbing Strakes

Not a great deal done to Naiad these last seven days, four were spend at another event, or travelling to and from Caldicot Castle where the event was held. The remaining three days were spent on home projects.

Still, on the (long) way back from South Wales we were able to stop off at the galvanisers to pick up the centre plate and tabernacle which have been waiting for a week or two. It was out of our way but not as far as going there and back from home.

As you can see, they look quite good. There are one or two high spots on the centre plate that will need to be taken off, I'll touch those up with a galvanising paint but considering the state of the centre plate it has come out very nicely indeed.

Today's task was to start attaching the rubbing strakes. This involves drilling holes in the timber and fitting the strake to the hull, then taking it off again, applying epoxy to the gunwale and then screwing the strake back on again. Each strake has 36 screws at 6" intervals and I managed to find a very good deal on 200 x 1 1/2" #14 silicon bronze screws. This also meant that I had to buy a pilot and countersinking bit as well as a plug cutter to do the job, you cannot easily screw in a #14 screw without splitting the wood unless you drill pilot and clearance holes. The countersink part is needed as since I want to cover the screw heads with a wooden plug and that means that the head must be positioned below the level of the wood.

Here you can see the starboard strake fastened in place and you can clearly see the holes into which the screws have been placed and which will be plugged once the rubbing strakes are glued. The buckets are to catch the water coming in through the holes in the roof when it rains and it has rained quite hard once or twice just recently.

The other rubbing strake was left in the position that I put it before I went away for the event, the idea being that some tension is kept in the timber so that it doesn't straighten out or not too much. Both timbers were left like this for the four days we were away.

Here we have the large countersink bit. The head of a #14 wood screw is 1/2" in diameter and the clearance hole required is 1/4" or 6mm. The bit makes a nice deep hold into which the screws are recessed.

The other half of the tool is the plug cutter and here you can see a plug cut out of a piece of scrap hardwood.

Once cut the plug is prised out with a screwdriver. The top of the plug as shown is rounded so that it fits easily into the hole made by the countersink bit.

And here is the plug loosely fitted into the screw hole. When the rubbing strakes are fitted and the epoxy has cured I'll glue in the plugs either with marine sealant or a water resistant wood glue as I don't want them to be permanently fixed, just fixed enough to stop them from falling out when the boat is being used. The plug should stand proud of the rubbing strake a little when glued in and this is to be carefully cut off with a sharp chisel and then sanded flush.