While Ann-Marie's anti-siphon technique is excellent, I have an even simpler method I use on my genset raw water.
I attached a small ID, 1/4" or 3/16", whatever fits, plastic hose to the siphon valve fitting, after removing the valve's guts, and lead it to the bilge with a big loop going as high as I can get it. When the pump is running the water rises in the loop but there is not enough pressure to push it over the top of the loop. When the pump stops all the water falls out. If for some reason the pressure with the pump on pushes the water over the hill it goes harmlessly into the bilge and the flow is limited by the small plastic hose. Norm S/V Bandersnatch Lying Julington Creek FL 30 07.72N 081 38.4W > [Original Message] > From: <[EMAIL PROTECTED]> > To: Rich Gano <[EMAIL PROTECTED]>; TWL2: <[EMAIL PROTECTED]> > Date: 2/4/2008 11:18:59 AM > Subject: (T&T: & TWL2:) Re: T&T Bilge pump plumbing (was Boat sunk at dock) > > > Yes, Rich, to answer your question you are missing something. > > It doesn't matter how high the loop goes, it will still siphon back if the > outlet gets below water level either by bad design, heeling, or the boat > sitting low in the water. When the bilge pump starts up, it fills the whole > loop with water. If air can't get back in from the outlet side, or a siphon > breaker, then it will siphon back over the full height of the loop. The > bilge pump will keep cycling until air finally gets in the outlet side or > the pump fails. > > The siphon breakers sold by manufacturers are an invitation for disaster. > They have a built in doomsday design. Read my article on the problem and > how to solve it at http://www.yandina.com/hints.htm#Siphon. With this > modification I've had siphon breakers operating for 14 years with zero > maintenance. > > Regards, > > Ann-Marie Foster, > [EMAIL PROTECTED] > > > > ----- Original Message ----- > From: "Rich Gano" <[EMAIL PROTECTED]> > To: "Trawlers-and-Trawlering" <[EMAIL PROTECTED]> > Sent: Monday, February 04, 2008 11:02 AM > Subject: T&T: T&T Bilge pump plumbing (was Boat sunk at dock) > > > > Why are pump hoses in some trawlers apparently not installed with loops > > high > > enough to prevent a siphon from starting? I cannot begin to think of a > > reasonable excuse. So what if holes have to be cut in cabinetry or soles > > or > > whatever - get the end of the loop up there! > > > > My boat came to me sans check valves, sans siphon breaks in the two bilge > > pumps, and I am not thinking of any changes. Their hoses run almost to > > the > > main deck level before doubling back down to exit near the waterline. You > > can flood the boat down three feet or heel it over at 30 degrees, and no > > water is coming back through those bilge hoses. Sure, it raises the head > > pressure a bit - so what? Get a bigger pump. Anybody ever had one too > > big? > > > > Am I missing something here? > > > > Rich Gano > > CALYPSO (GB-42-295) > > Southport, FL > > > --~--~---------~--~----~------------~-------~--~----~ > To UNSUBSCRIBE or change your email from live to digest or web board only, please send a request to Andina at [EMAIL PROTECTED] > POST messages in an email to [EMAIL PROTECTED] > View the live board at http://www.yandina.com/TWL2 > -~----------~----~----~----~------~----~------~--~--- _______________________________________________ Liveaboard mailing list [email protected] To adjust your membership settings over the web http://www.liveaboardnow.org/mailman/listinfo/liveaboard To subscribe send an email to [EMAIL PROTECTED] To unsubscribe send an email to [EMAIL PROTECTED] The archives are at http://www.liveaboardnow.org/pipermail/liveaboard/ To search the archives http://www.mail-archive.com/[email protected] The Mailman Users Guide can be found here http://www.gnu.org/software/mailman/mailman-member/index.html
