Recessed Deck Switches [49]

By Peter Provis

I’ve always thought that keeping a sea kayak deck simple and uncomplicated means less potential for things to go wrong. Nice clean deck, nice clean paddling strokes… to me it just feels good to paddle a kayak set up this way. So when I decided to fit electric bilge pumps to my kayaks, I looked around for a good switch design. As we all know, electrics and salt water don’t mix very well, but I’ve always thought that with good design and materials I could come up with a reliable system.

I adopted a method used by John Hyndman of the Victorian Sea Kayak Club, but changed a few of the components to suit my own needs for a recessed switch. All my boats run electric bilge pumps and the switch I’m about to describe has proved very reliable.

Basically, it is a small rocker switch, recessed into the deck, completely sealed under the deck in a ‘housing’ and on top of the deck by a long life butyl rubber membrane. This is the same rubber that is used in the building trade and I think it has a 20 year guarantee. That should be enough!

This is What I Collected

  • One 20 mm electric conduit joiner with cap in end,
  • Rocker switch—mini SPDT 240V round,
  • Four 15 mm x 4 mm SS countersunk bolts with nuts,
  • 3 mm marine alloy cover plate,
  • Butyl rubber sheeting 1 mm thick, and
  • Sikaflex marine grade sealant (preferably black).

This is What I Did

Firstly I decided where I wanted the switch. For me it was between the day hatch and the cockpit coaming—a location easy to reach in a rough conditions. A bit of a curve in the deck was OK because I could shape the aluminium to fit. The conduit joiner forms a switch housing under the deck. I roughened the outside surface of it, rounded the end a bit, and glassed it under the deck with the open end against the deck. This bit is easier if it’s done when the kayak is laid up, but it can also be done later.

All the components ready for Installation

Next, I located the glassed-in joiner position on the deck by shining a powerful torch beam up under the deck. I drilled and filed the centre out to the inside edge of the joiner. I placed the switch in the hole and marked around the flange with a sharp pencil. This area inside the pencil mark needs to be routered down about 2 mm to allow the rocker switch to work freely under the rubber. I used a router but it could be done carefully by hand I think.

I then cut the alloy cover plate to the shape I wanted and drilled and filed the hole out to about 25 mm. I drilled and countersunk the bolt holes in the alloy, being careful to ensure that they cleared the outside of the joiner under the deck enough to fit on the nuts.

I drilled a hole in the bottom of the joiner, pulled the pump wires through and soldered the connections on the switch. I dabbed some non-acidic silicone on the connections to insulate them. I then placed the switch in position, installed the alloy plate and drilled the bolt holes in the deck. While it was there, I marked the perimeter of the plate, removed it and scored the gelcoat with sandpaper.

I cut the butyl rubber to shape and using the hot soldering iron, burned through the rubber for the bolt holes. If you don’t do this and try to drill the rubber with the Sikaflex in place later you’ll make a big mess, believe me!

I applied Sikaflex to the scored gelcoat, and while holding the rubber to the back of the cover plate, pushed the bolts through and assembled the unit over the switch.

I tightened up the nuts just enough to slightly spread the Sikaflex and left it all to cure. Tightening it all up too much will spew Sikaflex everywhere, inside and out.

Lastly I sealed the wire exit at the bottom of the joiner in the hatch.

A Couple of Tips

  • A dob of sealant under the bolt heads will stop corrosion.
  • If you have to shape or bend the alloy plate to suit the deck shape, hit it from the back on a piece of carpet to prevent scratching.

If anyone wants to yak about this, I can be contacted on (03) 9787 1916.

See you on the water.

(Peter Provis lives at Mt Eliza in Victoria and is the Vice President of the Victorian Sea Kayak Club. Peter is a qualified AC Sea Instructor, paddles regularly on all areas of the Victorian coastline and has crossed Bass Strait. He also assists at monthly training days for VSKC members at Canadian Bay in Port Phillip Bay.)