Re: Washdown Pump
on every offshore boat, the pump is mounted in or near the bilge. You need a thru-hull connected to a valve, which then connects to the pump. the outlet side of the pump runs deckside, usually another fitting through the deck where you connect a hose.
you want to use a washdown pump and buy the largest capacity you can afford, trust me on that. the washdown pumps run when head pressure is lost (can't remember technical term, positive displacement pump?), so it runs when you spray, but turns off when you are not. I don't think a bilge pump works this way. I think the pump needs to be within 4 feet of the inlet to work properly, but closer the better.
I replaced the pump on my Grady 2 years ago. Can't remember the ratings, but Boat U.S. had 3 versions. I picked the middle one... bad move, big letdown compared to the original pump that Grady had installed. I'm waiting for this one to die so I can buy the biggest one I can find.