Hi Joe, This offseason I overhauled my 30-1's bilge plumbing, so spent some time thinking through the design issues. Wrote it all up at http://cnc-list.com/pipermail/cnc-list_cnc-list.com/2017-March/091421.html .
I use my manual diaphragm pump, a Whale Gusher 10 mounted under the cockpit sole, for pumping out the lowest inch+ of "nuisance water" every time I visit the boat - I don't mind. I rebuilt it last year with a rebuild kit after the old diaphragm tore. The electric pumps are for emergencies i.e. serious leaks. I leave them switched to automatic mode and their circuits are wired directly to the batteries. I calculate they could run for about 80 hours before depleting the batteries, if a leak starts while the boat is unattended. I was swayed by the opinion of a marine surveyor that there shouldn't be check valves downstream of electric centrifugal pumps in case they stick closed and prevent the pumps from doing their job. The link to that article is in the above posting to Stu's List. So I removed all check valves when overhauling Grenadine's bilge plumbing. As a result I have seen that my electric pumps can cycle when hose water drains back in, but it's not an issue because I pump out the nuisance water frequently enough with the manual pump. Grenadine's discharge is on her port quarter at the cove stripe, and the discharge hoses have high loops under the cockpit coaming there. If all that ever submerges deep enough and long enough to create a siphon, it means I've already got bigger problems i.e. my cockpit is submerged. Cheers, Randy Stafford S/V Grenadine C&C 30-1 #7 Ken Caryl, CO ----- Original Message ----- From: "Joe Boyle via CnC-List" <cnc-list@cnc-list.com> To: "cnc-list" <cnc-list@cnc-list.com> Cc: "Joe Boyle" <j...@zialater.com> Sent: Thursday, June 1, 2017 7:26:53 AM Subject: Stus-List Siphoning bilge pump hose? We had a nasty scare last night after our Wednesday night race. We were motoring back to the dock - about a half hour trip and I climbed down the companionway into about 2 inches of bay water. The bilge was full and overflowing as we motored along. Inspection revealed no leaks that i could see from the engine compartment - shaft log, water pump, muffler and exhaust and thru hulls were all fine. I jump up to the head and check all 3 thru hulls there - all dry. We finally get the auto bilge pump working and pumped all the water out - and no more leak. I believe that the float switch may have been stuck. So here's my theory - under power the 30 MK1 tends to squat and the bilge outlet is below the water on the stern. We had had rain the week before and I had neglected to turn on the manual switch to get out the last of any water in the bilge - the float switch always leaves a few cupfuls in the bilge. I am thinking that while under way with the outlet submerged, the bilge pump cycled on. Then - as usual - the remaining water in the hose flowed back into the bilge. But this time with the outlet underwater, it started water siphoning into the boat. After cleaning it all up I checked it in the morning - and it was dry as usual. The bilge hose has a high loop in it but no air break or check valve. I am thinking a check valve or an air break would keep this from happening again - any opinions would be welcome. Oh - and I think I will fix the manual bilge pump that I have been putting off for a while! thanks, Joe _______________________________________________ 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!
