Forward bilge alarm

[Phudpucker99]

Howdy folks... I have a 1-year old 310SLX and loving it.  But I'm not getting straight answers from the dealer regarding an annoying alarm that kicks in almost every time we go out.  I assume rain is getting into the forward bilges (under the mid-boat floor compartment), and everything's fine until we get up to about 10mph and all hell breaks loose with a screaming alarm.

I realize it's happening due to the rainwater surging backwards and kicking off the rearmost float-activated pump, but I don't understand why the alarm needs to activate if the pump's doing its job properly. At the moment I'm stuck with manually lifting the floorboards and hand-pumping the water out - very annoying as it happens frequently.  The dealers' guys all seem to think this is normal - which seems like a basic design flaw if it is.  Any similar observations or suggestions?

[CommanderB]

Yep, well intentioned design flaw.

I have the same on a 350 SLX - rainwater if I leave the covers off or washdown water sits in the forward bilge and surges forward tripping the built in float switch and sounding the alarm while the pump runs, normally only maybe 10s.

It is working as designed, if the forward bilge is full then the alarm is a good idea. But under many conditions the alarm goes off unnecessarily.

There are a few ways to solve this, but you shouldn't have to do this on a 1yo boat.

You can cut the brown+white wire on the pump. The pump will still work automatically but won't sound the alarm. You won't know when its working, but you also won't know if you have high water in the forward bilge.

You can wire the brown+white to a light to alert you silently, or to a manual override switch and run the pump manually before you go out.

I took a rather extreme approach (on a 5yo boat) and installed an additional bilge pump in the forward bilge. I teed in to the shower sump (which never gets used) with a non return valve. And wired it to run with the main bilge pump, which is auto but without alarm. The pump will run dry sometimes, shortening its life, but it clears the forward bilge such that the original pump with alarm never sounds. I am pleased with this solution, but it is not something you should have to do on a new boat.

Thinking about it you could probably wire in a delay switch, so that the alarm only sounds after the pump has been running for x seconds. That might be the most elegant solution. But not something you should need to do on a new boat.

Good luck!

[Phudpucker99]

Hi again, Commander B.  Well, it took me some months to get around to trying your solution and it certainly appears that the brown-white wire suggestion works.  The pump still operates but it doesn't scream anymore - so that's a god-send in itself.

However, it seems that was only part of the issue, and I now believe that the pump (while operating) is not actually draining the bilge at all.  Once I stopped the alarm screaming I figured I should test the rest of the function before closing the compartment - so I added a couple of buckets of water and manually lifted the float switch.  Sure enough the pump started whirring happily (a good sign), but the water level never dropped.  Please keep in mind that I've been hand-pumping this bilge since I bought the boat (brand new) because the alarm screamed whenever we went out and I needed a quick solution.  Background aside I now realize I was an idiot - because it now appears the drain probably never worked or I wouldn't have had to hand-pump anything.

So I disconnected the drain line (the 1" black one) from the side of the pump and tried blowing down it - but despite my best efforts all I did was break several blood vessels (joking) - I could not get any air through the pipe no matter how hard I tried.  So the question is - should I be able to blow through that pipe, and if not how can I prove it's draining?

Last note - when we first noticed the alarm problem (first time out on a shiny new boat) it looked to me like the pump was simply stirring the water (gushing out the sides of the pump body) which seems strange if it was functioning correctly.  I called the marina and basically got fobbed off ("oh, they all do that"), but I'm now suspecting the only reason that happens is the water has nowhere else to go??

Please forgive the lengthy post, but any insights you can offer would be greatly appreciated!  Happy boating, right?