Anchor/Chain washdown pump

[T37Chef]

Just installed mine last year and its one of the best things we've added. (Actually I found the pump, a Water Puppy, mounted on a bulkhead under the galley sink, LOL)

Anyway, I moved it into a locker near the head sink and T'd it into the thru hull for the head sink drain. I want to change the arrangement a bit, now the hose hangs from the anchor chain when everything is stored. I have run a hose along the deck so we can use it anywhere on the boat, including the galley sink.

BTW, does anyone know if you can add a pressure switch to these things?

I'll try to take some pics next time I'm down the boat.

Wilson, that is one sweet boat!!! WOW!!!!!

[Bene505]

Wash down pumps should have a pressure switch. At least mine does.

Originally Posted by tdw

You mean that pumps prefer to push than pull ? Or were you being quite literal and meaning specifically lift ?

To answer tdw's question, a pump's ability to lift water (into the pump) is limited by the amount of vacuum it can create. (And by the pressure of the outside air, which actually does the pushing. You can't actually pull on water.) And some pumps can't create a partial vacuum very well unless they are primed - already filled with water. Look for stats on the water lift height when unprimed.

IMHO, most good washdown pumps should be able to do several feet.

By way of example, I put a clear hose on the end of my little, 1HP (?), 120v shop vac, to make it easier to vacuum-dry the bilges after fall lay-up. With a clear hose, of course I tested to see how high it could lift water. IIRC, it can only lift water about 20 inches. That's all the suction it creates.

Even a theoretically perfect vacuum can only pull water 32 feet no matter what. That's all the height that air pressure can push water up.

On the other hand, down stream from the pump, pumps can actually pump water quite high. Just look at the fireboat display on the 4th of July, or other significant days, like when CruisingDad left the dock. (grin)

Regards,
Brad

[wwilson]

Originally Posted by tdw

Really ? I didn't know that. You mean that pumps prefer to push than pull ? Or were you being quite literal and meaning specifically lift ?

tdw,

Sorry if I confused. No I mean total lift. The pump can be positioned top, middle, or bottom within the column of water. It is the total vertical that is measured.

Just read Brad's post - agree completely. I think 33.9' (?) is the max theoretical and ~ 25' practical lift at sea level.

[jrd22]

Originally Posted by tdw

IIf not literal then JRD's idea of taking a feed off the raw water intake with a pump in the bilge (or thereabouts) makes a hell of a lot of sense. It doesn't overly complicate the thing , other than wiring to the switch.

JRD.......what did you use for the plumbing pipe ?

Probably on Raven we could still get away with the simple method as we are only 34' and lower in the bow than say a 40'er.

It's just 1/2" reinforced water line hose. Flexible, cheap and easy to run to far corners of the boat.