Second electric bilge pump

[mainemandean]

I know that check valves in bilge pump outlet hoses are frowned upon, for good reason. I do currently have one, though. It prevents pump cycling after all of the water in the hose (which did not get all the way to the thru-hull) comes draining back into the bilge. I am contemplating retaining the check valve in my current setup, but adding another electric pump, higher up, which does not have a check valve. The lower one will remain for workaday use, and the upper one is for emergency use. If all is well, the upper one will never have water in its outlet hose which can then run down into the bilge. But if you do use the higher pump, it just needs to be higher than the point in the bilge which represents the water height of both of the hoses having drained themselves.

I am wondering, folks: if I install this upper pump, is there any downside to having it tee into the outlet hose of the lower pump? I guess what I am asking is whether in an emergency, that single hose could handle the output of both pumps running simultaneously, without restricting the flow. My brain cannot quite get around that part. My guess is that it depends upon the diameter of the hose. (No, I cannot tell you from here what size my hose is, or what the outputs of the pumps--current and envisioned-- are.) If the bottom pump died, the water from the upper would not be able to go thru the tee and head down to the bilge, because of the check valve.

I am thinking that this upper pump would be in something like a plastic milk crate, and would hang in the bilge, about halfway down. The fitting to the outlet hose would be something that is easily detachable, so if you want to get at something below, you can haul up the basket, undo the hose, and get the pump out of the way. Similarly, the wiring would also need a user-friendly connector, or excess length.

Does this plan make sense?

Dean
Cape Dory 31

[sailingdog]

I would put in a second through hull for the second pump. The problem with having two bilge pumps discharge into a single hose is that if there is a clog, then you can lose both bilge pumps. Also, a clog could cause the smaller, "maintenance" pump to keep pumping by having the water come back down through the larger secondary pump... and killing your batteries.

A better way to mount the pump is to put it on a small board, and then have a pvc pipe "handle" attached to the board, so you can lift it up out of the bilge. You can cable tie the wiring to the PVC pipe or run it through the pipe to protect it.

[allene222]

I am not necessarily recommending this but I have three pumps and one outlet. However, the smaller pump has its own hose and the connection to the larger hose is right at the transom. A clog there is unlikely as there is no hose involved. The large pump has two valves in it spaced about a foot apart. On top of that are T'ed in fittings that go to a manual gusher pump. When I pump the gusher, the valves close in such as way that the water goes out and not back into the bilge. When the auto pump runs, water runs through both the hose with the valves as well as the gusher pump. I have had this setup for 20 years and it still works. Your question about having a pump high up is complicated by the fact that most pumps can push water but not pull it. You need a fairly expensive pump to pull water. Submersibles are much cheaper.

Allen