Hi My name is Paul.
I am from Mackay Queensland, Australia, We are on the mainland, beside The
Great Barrier Reef. I have an 5.75M (18ft) fiberglass, planing hulled half
cab. It is fitted with a 130hp Yamaha outboard.
In smooth water it planes at 30 mph. It will plane in rough conditions down
to 16 mph.

I want to set up a deck (actually bait cutting board... don't have a flush
deck) washdown pump and incorporate it so that it will supply and aerate
water to my live bait well. The pump I am planning on using is a Johnson 5
gpm model.
It is a diaphragm type with a pressure switch built in to it so that when I
operate the trigger hose assy. (supplied) the pressure drop activates the
pump. I am going to put a T piece in to the delivery line to allow me to
send water to the live well. A valve in the line will allow me to isolate
the live well supply line when it is not in use. I think I will have another
T piece in that line to allow me to bypass water if there is too much going
to the live well. (My concern is if I use the isolation valve to regulate
the live well flow it will result in the pump switching on and off a lot.)
I would be happy to hear of anyone's ideas suggestions or otherwise with
this arrangement. My reason for writing though is to ask what the thinking
is on installing the water inlet pickup.
I can put a plastic fitting into a hole that I would drill in the bottom of
the boat (on the planing surface... near the back ...say about a foot from
the transom). Or I can fit a stainless steel spear type of pickup that will
mount on the transom below water line at rest. The device I am talking about
is fitted so that the pickup pipe is a couple of inches under the water
while on the plane. The pipe is bent so that the open end faces forward and
when the boat is planing it will have water forced into it by the speed of
the boat, forcing water to the live well if the valving is open. The pump
could run in this situation but it wouldn't need to be running.

The pros and cons as I see them are...

Hole in bottom of boat method.
Pros
Out of sight.
Skin fitting would be less at risk of being stood on knocked off ect.
Cons
Will need to have a seacock fitted.
I don't expect there will be a forcing effect because the opening of the
hole will be at 90deg to the flow of water, although I am sure there will
be quite a bit of pressure there and it may force water in anyway.
Bubbles may be moved by slightly raised surface of fitting and affect depth
sounder.


Stainless steel pickup method
Pros
Positive forcing of water into pipe
hose could be routed so it enters transom above waterline, so as to avoid
the necessity for a sea cock ( I think I would still want one, for peace of
mind)

Cons
Doesnt look very elegant.
May be prone to being used as a step.

Does any one have any experiences with either method?
Thanks for taking the time to read this.
Cheers Paul.
Remove the word nospam from my email address if you wish to reply to me
outside the group.

Paul wants to have both a bait system and raw water washdown using the same
pump-he says:"..The pump I am planning on using is a Johnson 5 gpm model.
It is a diaphragm type with a pressure switch built in to it so that when I
operate the trigger hose assy. (supplied) the pressure drop activates the
pump. ....."

Paul most of the boats I have had (or seen) use a flexible (rotary) impeller
pump (similar to Rule or A****er bilgepumps 500gph to 750 gph) for the bait
system, with the diaphragm type pump usually used for a freshwater
galley/shower)system.
The rotary baitpump is a continous duty item that is not self-priming but has a
low amp draw, is generally trouble free and inexpensive to replace when the
time comes. With a "Y" valve the larger gph units can double as a washdown
pump.
I would use a through hull (bottom) pickup (careful to install so it won't hit
the trailer bunks!) with a good seacock, not just a hardware store ballcock,
mounted just inboard.
Use 100% stainless, band AND screw hoseclamps. Check, just 'cause it says
"stainless" doesn't mean the screw is. Double clamp everything you can as most
of this will be below the water line!
Check with what works for other folks in your area, and West Marine or BoatUS
have usefull info in their catalogs which you can access online.
Good luck
Mike