: Hi Tim, I've been kicking thoughts around in my head since last fall...I'd
: love to hear what you've come up with!

: I'm thinking of installing something along the lines of Pete Roszyk's
: Guzzler, except that I'd make a larger pump body and diaphragm for more
: capacity. I have the inlet and outlet flapper valves and pickup figured
: out pretty well. I really have no idea what to use for a diaphragm. I've
: often considered inner tube, and while it's a good piston pump seal, I
: think it would be too fragile for a diaphragm.

How about PVC for seal?

: I'm also still looking for the optimum pump body. My plan right now is
: 8" PVC SDR 35 pipe about 4" long. It's decent to glue to, and
: easily machinable, but slightly heavy. I'm still trying to figure out,
: too, how to securely attach the diaphragm to the end of the cylinder.
: Possibly a 1/4" thick ring of the same 8" PVC pipe with about 12
: or 16 screws evenly spaced about the perimeter, screwed through the ring,
: through the tube, and into the end of the pipe.

: I thought about making a short, fat woodstrip cylinder, but it's not as
: "machinable" and attaching the diaphragm to the top would be a
: bit more difficult.

Ever think of graphite powder mixed into epoxy FRP wrap around a DWV PVC pipe lined with wax paper. Wax paper should be able to prevent sticking. The structure will be thin enough that weight will not be a big factor.

: I kind of like Dave Blodgett's idea about running a pickup down the keel line
: and under the seat; the lowest point in the boat. I'm not sure if making
: one strong enough to not break when stepped upon would be worth the extra
: weight, but it's a cool idea.

Tygon tubing is sold with different thickness in Home Depot at very cheap price.

: Shawn