Our 37 XL has a check valve and a vented loop (belt and suspender approach) in the electric bilge pump discharge hose, like this: http://www.forespar.com/products/boat-marine-plumbing-vented-loop-thru-hull.shtml This loop is in the lazarette, above the thruhull in the stern.
Our manual pump does not have a vented loop but does have a one way valve in the strum box. The boat came with a one way valve in the strainer but when it started leaking we replaced it with a Whale #SB5865 Top Entry Strainer, this type: http://www.marineoutfitters.ca/index.cfm?category=10036|10159&product=17181806&code=766478586506 For the manual bilge pump to back siphon it would mean both the strainer valve and both the one way valves in the pump would have to be leaking so perhaps it is time to service the manual pump or at least clean the hair, etc. out of the valves? Ken H. On 13 August 2013 00:03, Colin Kilgour <charliekilo...@gmail.com> wrote: > The only problem with a check valve is that it reduces the flow rate. > > If you plan to use a check valve - as many of us, including me, do - > just adjust your pump size accordingly. > > Same goes for how big a column of water you're pushing (ie: hose diameter) > > Same goes for how high you're pushing that column. (ie: the higher the > loop, the higher the column - And btw, you definitely DO want a loop) > > Same goes for the gauge of wire and length of wiring run to your pump. > (Lower voltage = less flow) > > All of these impact flow rate. So your 2000GPH pump is actually > pumping a lot less than that.... Again, not a huge problem - as long > as you factor all these things into your de-watering strategy. > > Nigel Calder does a really good analysis of these factors in his > mechanical and electrical book. > > Cheers > Colin > > Btw - on Bojangles, the bilge pumps discharge well below waterline. > I'm not super happy about that, but that's the way the boat was made > and it'd be a major plumbing project to make it work a different way. > Touch wood - this has always worked well for me. > > > > On 8/12/13, Josh Muckley <muckl...@gmail.com> wrote: > > I must be messing up cause I have a check valve. Without it, all the > water > > that is pushed into the hose above the pump drains right back into the > sump > > once the pump turns off. With an auto sensing pump it would pump all the > > time. > > > > I did up size the discharge hose and check valve so that they would he > > harder to clog. > > > > Josh > > > > -- > > When privacy matters. > > http://www.secure-my-email.com > > On Aug 12, 2013 9:15 PM, "Steven Winks" <swi...@cogeco.ca> wrote: > > > >> ** > >> Hi. I have a 34+ and had an unusual thing happen this morning while at > >> anchor. I woke to the sound of my electric bilge pump cycling on and > off. > >> The bilge was full of water. I turned the pump on to drain the bilge and > >> it > >> filled up again once the switch was selected to off. I had the same > >> result > >> with the manual pump. When I removed the manual bilge pump hose from the > >> bilge and then turned on the electric pump again, the bilge stayed dry, > >> so > >> the water must have syphoned in via the manual pump discharge. The > >> discharge on this boat lies only a few inches above the waterline, but > >> with > >> any weight aft, it is below the water. Has anyone else experienced this? > >> I > >> understand check valves are not recommended. Thanks for any advice. > >> > >> _______________________________________________ > >> This List is provided by the C&C Photo Album > >> http://www.cncphotoalbum.com > >> CnC-List@cnc-list.com > >> > >> > > > > -- > Sent from my mobile device > > _______________________________________________ > This List is provided by the C&C Photo Album > http://www.cncphotoalbum.com > CnC-List@cnc-list.com >
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