I have had a few issues with the so called “waterproof switch” for the electric bilge pump that I had installed in my Mirage Sea Kayak. The rubber boot was broken, from doing cowboy entries into the kayak, allowing salt water to get into the switch. I have gone through two switches in six months and at $14.00 each it was going to get expensive. Not only that, but the possibility of the switch failing while I was on a trip when I’d need it got me thinking of an alternative switch. I was also not happy with having electrics in a place where salt water could get to them. I’ve always thought of a day hatch as a place you need to be able to get to on the ocean whatever the conditions.

The answer is an Air Switch usually used in a spa pool to turn the blower on and off. This comes in two parts, the plunger (190-0478) and the latching switch (319-736). I sourced both parts from RS Australia an online component store. By fitting this type of switch I was able to keep all the electrics in a waterproof box in the rear compartment and run an air tube to the box.

The plunger was placed where the hole was for the electric switch. I used a hole saw to enlarge the hole. Because of the curve of the hull I used a small amount of epoxy glue to seal it off.

The 4mm air tube runs through the rear bulk head to the waterproof box.

The only thing I’d do differently would be to use a different box that didn’t need a screwdriver to open it.

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The box, showing the Latching air switch, with the 4mm air hose attached.

Plunger, top view

Plunger bottom view (complete with Daddy Long Legs spider)

Box with battery installed