Electric pump in Rockpool GT

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Electric pump in Rockpool GT

Quick links: Pump - Battery - Plumbing - One way valve? - Switch - Wiring - Operation - Notes

In lessons learnt from previous installations I'm trying out some new ideas. As backup I have a regular manual pump and sponge.

Pump

The Rule 500 is still the default choice. There are sophisticated versions that switch on and off automatically but I want manual control so the basic version is fine. I want the pump to be at the lowest point so its located behind the seat. When you need to pump out the dregs a forward stroke or two will slosh them towards the pump. The pump is quickly removable from its base which is glued to the hull by araldite (sand both first)."

Battery

Last time I had a 2.2 AH version

Plumbing

The previous design involved a hose that had to be manoevered out of the cockpit and under the spray deck. This would be too fiddly in a tight situation so this time around it had to be a hole in the boat and a 'skin fitting'. I didn't want to put a hole in the hull around the cockpit region as that is an area of high stress / weak point in the structure of a kayak. I've built the output into the foredeck about 150mm forward of where my right knee fits

One way valve?

Some water may splash in through the outlet. Commercial one way valves can clog with sand and also are known to restrict the flow. I've used a bung made from medium density closed cell foam (e.g. old swim float or garden kneeler) with a 1mm string going through the centre

Switch

I think this is the trickiest part of the installation. Many different solutions have been implemented. I'm trying another 'blue sky' approach that bears some relation to my previous versions. It's built into the hatch cover of the pod so its directly in view

Wiring

The intention is to keep the number of components and wiring to a minimum. Where wires pass through bulkheads I've used Maplins smallest grommets. Holes have to be drilled to just the right diameter and the grommets can be fiddly to fit

Operation

Presuming you are out of the boat and in the water:

Re-entry roll upright
Switch pump on and pull out the bung
Put spraydeck on
As spray deck lowers with partial vacuum, ease side of spraydeck to allow air in (to replace water pumped out).
When the pump starts sucking air the flow quickly ceases and this is easy to see as the outlet is directly in view. Then it's best to switch the pump off, wait 10 seconds or so then retry, the froth having gone, the pump will get a fresh start on the dregs. Also, it's worth a quick accelerating stroke or two to slosh any remaining water from the front back to the pump.
Switch pump off, replace bung.

Pump-out from a depth of water covering the pump takes about 2 minutes.

Notes

All up weight of pump installation is ~1.5 kg
I've found a Wickes 22mm tank waste 90 degree fitting that looks good and will be trying that instead of the existing skin fitting.
For previous installations see here"

Skin fitting showing bits used (top) and discarded (bottom).

Inside view of hose to skin fitting and switch wiring to pod.

Pump in situ.

Pump, backup bailer and sponge.

Switch and outlet.

Switch underside.