Well Gary, after reading those articles and thinking about the issue all evening yesterday, here are the conclusions I came to. The wiser and more experienced C&C owners on the list may have more well-informed perspectives on this whole matter.
It seems bilge pumping systems have two main purposes. First and most important is keeping the boat afloat as much as possible as long as possible in case of a hull flooding event from whatever cause. Second and less important is getting rid of nuisance water that accumulates in the bilge for whatever reasons. For the second purpose, diaphragm pumps are apparently best. Given an appropriately-placed intake hose, they can suck the lowest sump dry. And they have the power to overcome the head pressure of check valves and standing water in the discharge hose, where centrifugal (Rule) pumps don't. But for the same price and size they don't have nearly the capacity (in GPH) as a centrifugal pump. For the first purpose, if you take David Pascoe's recommendations, a 40' sailboat should have three pumps totaling 6000 GPH capacity, with two of those being redundant Rule 3700s. He seems to think 3000 GPH is needed to keep up with the inflow rate caused by, say, the loss of a prop shaft or rudder. He writes a 27-35' sailboat should have three pumps totaling 3500-4500 GPH capacity. In Grenadine's case, she already has a diaphragm pump - a manual Whale Gusher 10 mounted below the cockpit sole, with intake hose in that lowest sump under the mast step. Last year I used that pump to suck that sump dry when visiting the boat, and I'll continue using it to evacuate nuisance water when I visit the boat (which is often). I don't mind; Grenadine is a dry boat, and getting drier. Due to the Whale Gusher's location it's relatively serviceable - last year I serviced it with a rebuild kit including new diaphragm and valves etc. Today I measured Grenadine's lowest sump, under the mast step, and determined that a Rule 3700 at 4&7/8" diameter won't fit. However I believe a Rule 2000 at 4&1/4" diameter will fit. So my current plan is to install a Rule 2000 with separate float switch down in that sump. It's only there to address purpose #1, so I'm not worried about backflow from it, and I'm not plumbing a check valve into its discharge hose. Again I'll frequently pump out any nuisance water with the Whale Gusher. David Pascoe and others recommend strongly against check valves in centrifugal pump discharge plumbing. Given the space constraints the only way to get redundant Rule pumps down in that sump would be to use a pair of non-automatic Rule 1100s with manual switches or separate float switches - I think the pumps would fit, but maybe not two float switches in addition. For redundant Rule pumps on Grenadine I think I'll just put the automatic Rule-Mate 1100 that came with the boat farther back and higher up in the bilge, aft of the aft mast step support. I'll have to wire a new circuit for one of the two electric pumps (probably the new Rule 2000). Regarding discharge plumbing, Grenadine has a 1.5" discharge port on her port quarter at the cove stripe. A previous owner teed the 1.125" discharge hose from the Rule-Mate 1100 into the 1.5" discharge hose from the Whale Gusher with some PVC components near that discharge port. And he put a heavy, metal check valve upstream from the tee on the 1.5" discharge. The whole assembly is hanging by a combination of pipe strap, small nylon line, and zip ties. It's a hokey setup and I'm going to redo it completely. I envision wye-ing the Rule-Mate 1100 discharge hose into the Rule 2000 discharge hose, then immediately expanding that into a 1.5" discharge hose, all down in the bilge. Then I'll have two 1.5" discharge hoses converging at the discharge port - one from the Whale Gusher, and one from the Rule pumps. I think I'll put a riser loop in each, up under the cockpit coaming (hanging from winch bolts) and therefore above the discharge port, then wye them together just upstream of the discharge port. The riser loops should prevent one discharge hose from backflowing into the other, and should eliminate the need for any check valves. And I shouldn't get backflow into the boat from the water outside unless the port cockpit coaming is underwater, which means the boat is stuck on its ear or down by its stern and the cockpit is flooded and I've likely got bigger problems already. I thought about discharge plumbing to the galley sink or cockpit drains, but the scheme above seems simpler and safer. Then finally there is the matter of powering those Rule pumps in a hull-flooding event. I see two cases: hull flooding happening while the boat is in use, or when the boat is unattended. The in-use case is easier: the users of the boat can run the engine to charge the batteries to power the pumps until the boat is safe or the gas runs out and the batteries deplete (in which case the boat will sink). When the boat is unattended, I'll leave the pumps in automatic mode and ensure they're wired to have power even when everything else is switched off. Grenadine is wired for shore power and has a 110V battery charger so, in theory, if she's plugged in to shore power and suffers a hull-flooding event, her bilge pumps could run forever. If she's not plugged in to shore power and suffers a hull-flooding event, I'll have to trust that someone notices water streaming out of the discharge port and calls me before her batteries deplete (she has a solar charging system too). If I'm *really* worried about that last case, I could install a bilge alarm and annoy the whole marina to save my boat. So, that's how it breaks down for me. This whole matter has dominated my thoughts for about 24 hours now. When I'm done, I'll have met David Pascoe's recommendations: three pumps total, and redundant electric pumps, with an overall capacity of 4120 GPH (the Whale Gusher 10 has a capacity of 1020 GPH at 70 strokes per minute). Incidentally I'm in the middle of the mast step rebuild project right now, a la http://cncphotoalbum.com/doityourself/maststep/maststep.htm . My rig has been down and off the boat all winter so I could do that project and a chainplate resealing project. That's why I'm redoing all the bilge plumbing now too, and torque-ing the keel bolts. I want to get all those bilge-related projects done, so I can leave the rig up in future offseasons, and have confidence that the pump under the mast step is new and reliable :) Pictures of these projects at https://drive.google.com/open?id=0B-NqAxQ6JxFTaUlpUkZJWGt5RVk . Cheers, Randy Stafford S/V Grenadine C&C 30-1 #7 Ken Caryl, CO ----- Original Message ----- From: "Gary Nylander via CnC-List" <cnc-list@cnc-list.com> To: "cnc-list" <cnc-list@cnc-list.com> Cc: "Gary Nylander" <gnylan...@atlanticbb.net> Sent: Thursday, March 23, 2017 9:05:11 AM Subject: Re: Stus-List Automatic Bilge Pump? Recommendations? As I share the same design (30-1) with you and have that really deep sump right under the mast, I have agonized over this issue a bunch. First, you have to get all the water out or your sump will always be wet and your mast step will degrade. Second, if you come up with a good way to install a vented loop, let me know. I have a check valve in the line from the Rule pump which is in the bottom of the sump. I know the limitations, so I have my pump on a manual switch, so it won’t drain the battery. It is marginal. I am going to add a diaphragm pump to the system and have the intake tube in the sump and the pump under the dinette seat. The vented loop and discharge - ???. If I run it back to the stern or aft quarter like my Whale hand pump and Rule, then a bunch of water will come back to the pump when it cycles off. I am trying to figure out how to run the discharge into the head area above the holding tank, put a vented loop right under the deck and then exhaust through the side, but that may allow water intrusion when heeled over. Still measuring. This probably won’t happen until next winter – many other projects this time plus the mast is still up and I may pull it next year. Gary #593 From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of RANDY via CnC-List Sent: Thursday, March 23, 2017 1:41 AM To: cnc-list <cnc-list@cnc-list.com> Cc: RANDY <randy.staff...@comcast.net> Subject: Re: Stus-List Automatic Bilge Pump? Recommendations? Revisiting this thread, as I came across a few interesting articles today: * http://www.yachtsurvey.com/bilge_pumps.htm * http://www.docksidereports.com/bilge_water_blues.htm * http://www.sailnet.com/forums/gear-maintenance/93937-bilge-pump-non-return-valve.html I found those googling about bilge pumps and check valves, as I'm in the middle of overhauling Grenadines' bilge pumping system which currently has check valves in it. Then it occurred to me: maybe I ought to think about the design principles for my bilge pumping system :) Instead of just refreshing what's there with new components implementing the same design. The articles were good for provoking thought about that. I came to some conclusions that seem right for my situation. Cheers, Randy ----- Original Message ----- From: "David via CnC-List" < cnc-list@cnc-list.com > To: "cnc-list" < cnc-list@cnc-list.com > Cc: "David" < davidrisc...@msn.com > Sent: Wednesday, March 8, 2017 3:46:40 PM Subject: Re: Stus-List Automatic Bilge Pump? Recommendations? If you have a catastrophic failure good batteries and luck (attentive neighbors?) will save her on the mooring. If you have bilge pump counter on an automatic telling you the pattern of pumps per time period left unattended, you may see a problem before it gets out of hand. And hardwired to battery with fuse... Cheap insurance. David F. Risch (401) 419-4650 (cell) From: CnC-List < cnc-list-boun...@cnc-list.com > on behalf of David Knecht via CnC-List < cnc-list@cnc-list.com > Sent: Wednesday, March 8, 2017 3:45 PM To: CnC CnC discussion list Cc: David Knecht Subject: Re: Stus-List Automatic Bilge Pump? Recommendations? I am curious about the logic of this. My boat is on a mooring unattended for days at a time. I have a manual bilge pump that I turn on if necessary. If I am not on the boat and a serious leak develops, the pump would run until the battery is dead and then the boat would sink. So under what circumstances would you expect an automatic bilge pump to save the boat? Perhaps a slow leak? Also, I normally turn off all the boat power when I leave. If you have an automatic switch, do you have the switch wired directly to the battery, or do you leave you electrical system on when you are not on the boat? Dave Aries 1990 C&C 34+ New London, CT On Mar 8, 2017, at 3:31 PM, Matthew L. Wolford via CnC-List < cnc-list@cnc-list.com > wrote: Remarkably, my boat was not equipped with an automatic bilge pump, but instead has an external pump located near the nav station operated by a circuit breaker switch. I recently purchased a Water Witch for the bilge and a three-way switch for for the circuit breaker panel. _______________________________________________ This list is supported by the generous donations of our members. If you wish to make a contribution to offset our costs, please go to: https://www.paypal.me/stumurray All Contributions are greatly appreciated!
_______________________________________________ This list is supported by the generous donations of our members. If you wish to make a contribution to offset our costs, please go to: https://www.paypal.me/stumurray All Contributions are greatly appreciated!
