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Thread: Diaphragm pump under helmsman's seat - stupid idea?

  1. #1
    Advanced Beginner bgary's Avatar
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    Diaphragm pump under helmsman's seat - stupid idea?

    One of my projects this winter is to re-vamp my bilge pump system. At present I have a Rule centrifugal sitting on top the keel bolts in the main bilge. It works, but... it doesn't produce an impressive flow. Probably in part because it has a long uphill run from the pump to the exit under the transom, and centrifugals don't do "lift" very well. Plus, that whole long run is full of water when the pump shuts off, and since centrifugals don't act like check-valves, that's a couple gallons of water that drains back into the bilge.

    A diaphragm pump doesn't have to be in the bilge, so there are a lot more options. One of the options I'm thinking of is mounting the pump right next to the exit thru-hull in the stern. My thinking is that when the pump shuts off the long run of hose to the bilge will be empty, and it'll act like its own check-valve at the top of that run to keep any water migrating back into the boat.

    There's a molded structure under the helm seat, in between the thru-hulls. Looks to be about 1/4" thick, and seems pretty solid. I'm thinking of mounting the diaphragm pump there, but... I don't know if there's anything under that structure. I can see the end of a (long abandoned?) blower hose, but don't know what else might be lurking there.

    Anyone done anything in that area of the boat? Is it usable structure, strong enough to support a vibrating diaphragm pump, or is that a Really Bad Idea?

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    "Makana" (ex-Thelonious)
    1985 Ericson 32-III #604
    Makana blog: here

  2. #2
    1984 Ericson 30+, Nanaimo, BC
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    On my pump I have had to replace the impellor a couple of times. Is your planned location one that is sufficiently accessible to do that job?
    Frank

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    Advanced Beginner bgary's Avatar
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    Quote Originally Posted by Frank Langer View Post
    On my pump I have had to replace the impellor a couple of times. Is your planned location one that is sufficiently accessible to do that job?
    Yes, it's actually a pretty big / wide-open space under the center of the helmsmans seat. It's the same path for accessing the 6 thru-hulls under the stern counter. It'd also be simple to get both hoses and wires to that spot. And should be simple to view (and clear) an inline strainer installed upstream of the pump.

    Worst case, it would be easy to disconnect and unmount the pump from that spot, and replace the impeller (actually, diaphragm) at leisure on a bench if needed.

    Bruce
    "Makana" (ex-Thelonious)
    1985 Ericson 32-III #604
    Makana blog: here

  4. #4
    Moderator Christian Williams's Avatar
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    We may have talked about this, but here's where I put my diaphragm pump. They have a higher "head" than submersibles, even though the output is less.

    http://www.ericsonyachts.org/infoexc...Considerations
    Thelonious II, E381 hull 513 (1984) Universal 5432
    Table of Contents for Thelonious Blog here
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  5. #5
    Advanced Beginner bgary's Avatar
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    Yes, we talked about it (thank you!). In no small part, my path is based on your work - and illuminating that a centrifugal pump has a number of issues that a diaphragm pump minimizes.

    A centrifugal loses a significant amount of its rated flow as a result of things like hose-length, lift and turbulence... meaning that a centrifugal rate at 25gpm (the nominal "1500 gph" printed on the side), really only pushes 2 or 3 gallons per minute out of the boat, and the water in the hose when it shuts off comes right back down into the bilge. According to what I've read, a diaphragm rated at 4gpm actually has a good chance of pushing pretty close to 4 gallons per minute out of the boat, and works as its own check-valve.

    So my current quandary is where to put the pump. The obvious options are

    -- near the bilge (e.g., in a seat locker, as you've done)
    PLUSs are it's protected there, the wiring is simple
    MINUSes are it takes up space in the seat locker, and there will be a hose full of water upstream of the pump when it shuts off

    -- near the thru-hull
    PLUSs are it's a short run to the thru-hull, and it'll suck the downstream hose (to the bilge) dry, and I can re-use the existing hose paths.
    MINUSes are, its less protected, and less convenient to work on if needed, and the wire-run will be longer

    Dunno.

    I've ordered the pump. I think - before I do too much - I'll put it up on a cockpit seat and run a hose down to the bilge to see if it will *really* pull its rating worth of water up that distance and height. And do the same thing with the pump sitting on the sole to see if it will *push* its rating worth of water up that distance and height. That'll probably tell me... something.

    I love what you did with your switch, and with the extra length of hose to suck water out of other bilge pockets. Lots of goodness there.

    Bruce
    "Makana" (ex-Thelonious)
    1985 Ericson 32-III #604
    Makana blog: here

  6. #6
    Principal Partner Rick R.'s Avatar
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    Our diaphragm pump is on the bulkhead in the engine compartment. Plenty of room there for both the pump and the strainer.
    1989 32-200
    S/V "Easy"
    (hull #844)
    Pensacola, Florida

    The difference between a sailboat and a power boat? On a powerboat you rush to get somewhere. On a sailboat, you're already there.

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    Contributing Member I
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    Thatís where mine is

    Bruce, after playing around with Rule pumps and experiencing all the same issues you noted, I put a diaphragm pump under the helmsmanís seat just where you are planning. Used a water witch and a strum box that I heated up and molded a bit where it fits perfectly between the keel bolts. That was in June this year and it has worked perfectly so far.
    Phil Nelson
    1985 E32-3, M-25
    Valkyrie

  8. #8
    Advanced Beginner bgary's Avatar
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    Quote Originally Posted by Pnelson View Post
    That's where mine is
    Cool!

    Any tips? Photos? Which pump did you get? Did you just drill holes and screw the feet onto that raised/molded panel, or ...? I don't know what's under that panel, so I had thought (?) about bonding a panel of G-10 in place, and fastening into that, just to be safe. Or something. (I hate drilling holes in boats)

    Would love to know more about your strum box, too. I haven't yet found one that will fit between the keelbolts, hadn't thought about melting one to shape it.

    Bruce
    "Makana" (ex-Thelonious)
    1985 Ericson 32-III #604
    Makana blog: here

  9. #9
    Principal Partner Bolo's Avatar
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    Jabsco Shower Drain and Bilge Pump

    My E-32 has two bilges, a main and a mast/shower bilge, as you probably know. The mast bilge almost always has water in it from the mast and at one time I even had a one-way valve installed (Yes, it did make me nervous) to keep the "back-wash" from happening when the rotary pump stopped. It really was quite unacceptable. But then I saw Christian's work on his bilge and it inspired me to changed things. Out came the rotary pump and in it's place, in the mast bilge, I installed the strainer (screw to the side wall) and a short length of hose down to the bottom of the bilge. The end of that hose wasn't cut square but off at and angle so the one end of the cut touched the bottom of the bilge and the other side of the cut was lifted about 1/4" off the bilge bottom. This allowed me to suck out nearly all of the water from the bilge with the Jabsco Shower Drain and Bilge Pump (model #37202-2012 About $255 from Defender) which I located in the stern where the hose exits the boat. There is a piece of plywood back there that was the perfect space to mount it on. I used a mechanical pump switch in the mast bilge that I think has a delay of a few seconds before shutting off after the water is pumped out. I sorry that I don't know the brand or make right now. This setup has worked perfectly. I had all of the intentions of doing the same to the main bilge this year but other things got in the way so it's on the top of my list for projects next spring. BTW - The Jabsco Shower Drain and Bilge Pump (model #37202-2012) has a cover over the moving parts of the pump which keeps it from getting tangled up with anything the the after locker. The older version of that pump doesn't have the cover.
    Bob Skalkowski
    1987 E32 III (#722) - "Vesper"

  10. #10
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    Whale 320 pump

    Bruce, sorry I don't have any pictures, but I will be going down to the boat tomorrow and will take some. The pump I used is a Whale Gulper 320 high capacity pump, got it at Hodges Marine for $137. The strum box is a Whale water systems top entry box with built in check valve. The check valve is not necessary with the diaphragm pump, but it is built in and I didn't find it available without the check valve. I used water witch 230 electronic level switches, and they are working fine so far. I tried the rule centrifugal pumps, as that was what the PO had used, but they won't pump through a check valve, and if you take out the check valve, half the bilge fills up from drain back, making it an endless cycle of pumping up and running back. I did keep the rule pumps in the mast bilge and the shower bilge, but they just pump to the main bilge where the diaphragm pump clears it out and it doesn't run back. I will try to post some pics tomorrow.
    Phil Nelson
    1985 E32-3, M-25
    Valkyrie

  11. #11
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    Bruce,
    Here are a couple of pics of my bilge pump install. I used one of the existing hoses running aft, inserted the pump where the hose exits the covered channel, left the anti-siphon loop, and ran it out the thru hull. One of the features of the Whale 320 is the head unit will rotate to allow flexibility in mounting. I oriented it up and down, so the inlet is not visible in the pic. You can see the Whale strum box installed between the keel bolts, and the water witch is just silicone in place. I need to lower it a bit, it leaves about 1/2" of water in the bilge. The other hose that is zip tied to a keel bolt is coming from a Rule pump in the other bilge compartment. And yes, the pump is screwed directly to the channel cover, but you can feel underneath and verify that nothing is in the way. I am happy with the setup so far, but it is the first season, so time will tell.
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    Phil Nelson
    1985 E32-3, M-25
    Valkyrie

  12. #12
    Advanced Beginner bgary's Avatar
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    Quote Originally Posted by Pnelson View Post
    Here are a couple of pics
    Thank you, Phil!

    I'll update this thread as my plan evolves....

    Bruce
    "Makana" (ex-Thelonious)
    1985 Ericson 32-III #604
    Makana blog: here

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    The rule 1500 sitting in my bilge has been more than adequate and its flow is only slowed by the small passages between the stringers in the bilge compartment. There is a check valve to prevent backflow. While I understand this is not recommended we have had no issues whatsoever. As a backup a manually operated whale gusher is accessible immediately in the cockpit. I believe the boats were originally equipped with diaphragm pumps installed either under the quarter-berth or in under the port salon (occupied by the water heater + stove fuel tank on my boat.)
    ~-~-~-~-~-~-~
    1981 Ericson 30+, rocking the Juan de Fuca

  14. #14
    Principal Partner gadangit's Avatar
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    Anybody have any idea if using 1-1/8" hose on a pump that has a 3/4" inlet/outlet is a problem? I'm thinking of replacing one of my centrifugal pumps with a diaphragm pump and I'd like to intercept the existing hosing somewhere along the run.

    Chris
    Chris and Lisa
    1972 Hull #53 Ericson 39 "SolAire"
    San Leon, TX

  15. #15
    Advanced Beginner bgary's Avatar
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    I've now experimented a bit, and convinced myself that the Jabsco diaphragm pump has enough "suck" to pull water up from the bilge and out, from a position under the helmsman's seat. So... now I'm working through the details.

    One of the details is... all of the conventional wisdom is that the bilge pump should be connected directly to the battery, so that it is live even if the battery switch is off.

    Mine currently goes through a breaker on the panel, and is off when the battery switch is off.

    Part of me is okay with that - my battery switch is always "on", so as long as that breaker is also always "on", my bilge pump will have power. But... stuff happens.

    So... if I'm going to do this, what's the right way to wire an 11a pump (and associated switches) directly to the battery? I know I could (for example) run the wire to the "battery 1" post on the back of the battery switch, seems a little crude but that way it would always be connected to #1. But... I suspect there's a smarter way to do it.

    Bruce
    "Makana" (ex-Thelonious)
    1985 Ericson 32-III #604
    Makana blog: here

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