Manual bilge pump plumbing

[Josephcrawl]

Our boat came with with a whale bilge pump in the cockpit. It was unfortunately not plumbed to an out pipe so all it was good for was circulating the bilge water.

The most convenient pipe to plumb to was the port side scupper. So I cut into it and added a T. It pumps out now but drains poorly and has a tendency to back up through the scupper. Should I just add another thru hull? Or do I need to add some type of vent?

Thanks

[mike d.]

It drains poorly because the scupper drain has back pressure ! This is Normal, as there is water already in the line, if your scuppers empty as ours do ! We have 1 1/2 inch sea cocks, 1 per side under cockpit in engine room ! 4 cockpit drains, 1 1/4 inch to t in through hulls ! The Whale gusher emergency bilge pump is plumbed into the port side rear cockpit drain ! Surveyor said it was fine ! I guess if you look at it in that the emergency pump is used very aggressively, to keep boat afloat, then flooding the cockpit makes a certain amount of sense ? I would run a thru hull out the transom if you can strictly for that use ! No back pressure ! If you are worried about surge from aft, put a flapper on the discharge flange 1