Diaphragm pump under helmsman's seat - stupid idea?

bgary

Advanced Beginner
Blogs Author
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?

IMG_3759s.jpg
 

Frank Langer

1984 Ericson 30+, Nanaimo, BC
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
 

bgary

Advanced Beginner
Blogs Author
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
 

bgary

Advanced Beginner
Blogs Author
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
 

Rick R.

Contributing Partner
Our diaphragm pump is on the bulkhead in the engine compartment. Plenty of room there for both the pump and the strainer.
 

Pnelson

Member I
That’s 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 helmsman’s 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.
 

bgary

Advanced Beginner
Blogs Author
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
 

Bolo

Member III
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.
 

Pnelson

Member I
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.
 

Pnelson

Member I
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.
 

Attachments

bolbmw

Member III
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.)
 

gadangit

Member III
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
 

bgary

Advanced Beginner
Blogs Author
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
 

Christian Williams

E381 - Los Angeles
Moderator
Blogs Author
I ran heavy wires, with an in-line fuse, direct from pump to the battery posts.

If this is not best, waiting to hear.
 

Frank Langer

1984 Ericson 30+, Nanaimo, BC
Bruce,
While having the bilge pump wired on at all times may be good, there can be a problem if you use an old style mercury switch or similar float level in the bilge. I found that when the boat heeled under sail the float switch fell open due to the heeling angle and started the pump even though the bilge was dry. Running the pump unnecessarily, especially if one uses an impellor pump, is not good.
So if you decide to wire it directly to the battery in some way, think carefully about what kind of switch you use in the bilge.
Frank
 

Frank Langer

1984 Ericson 30+, Nanaimo, BC
Bruce, if you want to get fancy with your wiring, I rewired our bilge pump (also a remote mounted Jabsco pump) as follows:
I have a small push button in the head to operate it to empty the shower sump, also can turn it on continuously with the switch on the dc panel, and have a conveniently placed auto/off/manual switch. Any of these will operate the same pump independently of the other switches.
When sailing, I keep them all off to avoid the pump coming on when my float switch opens when heeling a bit more than usual. I keep it on auto when away from the boat in case an unforeseen leak occurs.
While I generally favour simplicity on my boat, in some cases redundancy can be a good thing. I forgot to mention that I also have a manual whale gusher pump in the cockpit, and I know how to undo the raw water intake hose from the seacock (after closing the seacock first) so it can suck water freely in the engine compartment if needed.
I think I'm prepared to deal with a water leak, but hope I never have to do so!
Frank
 
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supersailor

Contributing Partner
From a guy who has experienced a major inflow into his boat, a single 12v bilge pump is woefully inadequate. If anything happens, your boat will go down. Mine did, Salt water is an amazing destroyer of almost everything. $30,000 and a year later Terra Nova is almost new.

The way the 34 was wired, the shower pump would only work if The pressure water was turned on. If it had been wired like the bilge pump, the two might have kept up with the inflow.


After much thought and input from you guys, I also added a 110v Rule pool pump. It shoots water like a fire hose. I now am comfortable leaving the boat in the marina.


That single bilge pump is fine for incidental leakage into the bilge but if there is a real inflow, your boat will go down. Mine did. A second pump is a cheap investment. In the 34 at least, rewiring the shower pump will give you a backup once the bilge water reaches the soul level. The centrifugal pumps are cheap and that's the best I can say for them. What's your boat worth? Shouldn't you protect it?

Also, I have been aboard some boats where the pump isn't working at all. It may be due to a frozen shaft or corroded wiring. A leak and your boat goes down.


PS/ The pumps are optimized to handle the water that they can pump. Enlarging the output hose will not increase the output.
 
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Frank Langer

1984 Ericson 30+, Nanaimo, BC
Bob, did you add the Rule pump to the existing circuit and hoses so your pumps work in tandem or is it a replacement for the diaphragm pump?
More details on your set up would be helpful. ☺
Also, you've referenced health problems in some of your other posts - - I hope you're recovering quickly from whatever is keeping you from sailing.
Frank
 
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