: I have an idea. I believe I heard it somewhere on this board, but why not put
: a hole in the top of the kayak under the compass mounting plate. There
: could be grooves in the bottom of the compass mounting plate to let the
: water flow out the sides of the plate and down the side of the boat, but
: you wouldn't see the outlet hole.

Thank would be really cool. The only tough part would be the plumbing. You'd also have to make the compass removable so that you could clean out the outlet if any stuff got clogged up there.

: Also, if you make the inlet go in the bottom, then out the top of the pump
: you won't have the water going back and forth at the tee. It will flow in
: one direction only. Plus you won't have the restriction of a tee.

Well, that was my original design, but that would leave the pump housing full of water once you started drawing air (you draw in air, it rises in the pump and gets pushed out, leaving the space between the end of the housing and the end of the plunger filled partly with water). The idea of the tee was to localize the location of any potential clogs in an easily removable part. Since the pump is not dual flow (pumps on the in and out stroke), the water never moves in an out at the same time. However, the water above the tee would have some inertia that you have to oppose. I plan to choose a intake/outflow diameter large enough to avoid restriction problems.

: I agree that you would need a long bushing, or a couple of supports for the
: piston rod so it would go in straight and not bind up.

Yep a long bushing sounds about right with lots of grease. I'm also concerned with choosing a spring or the right strength and diameter...

: Wouldn't you need a hole in the aft end of the pump to let the air in the
: area between the piston and the aft end go in and out and not build up
: pressure/vacuum?

Absolutely. I'm sure that would have been the first in-place modification that I'd have made. :-) There should definitely be one or two air holes in the end cap. Something occurs to me though. If the cockpit is entirely full of water, then water will be sucked into the end cap and the breather hole would have to be large enough to allow the water to leave quickly when the pump draws. This might mean that a large number of breather holes need to be drilled, and there needs to be at least one towards the bottom of the end cap to allow water to drain from behind the plunger when the boat is upright and the cockpit is empty.

Thanks for the input!

Later,

Tim.