Bilge Pump Protection

Hi,

I am in the midst of designing a simple circuit to:
1. sound an alarm if water reaches a set of probes in the bilge and
2. sound an alarm if the bilge pump runs for an extended period of time (say 2 minutes)

What has prompted this was nearly sinking our 52ft catermaran that we had only had 2 days. Combination of a badly leaking shaft gland and some fishing line in the bilge pump.

I have put together a circuit to solve item 1 using a couple of transistors etc but I am open to suggestions for something to do item 2.

Any suggestions?

I have seen a couple of commercial systems around but they cost $100's for what is realy only a couple of $'s worth of parts.

Once I have the project finished I'll be happy to share the design with anybody who cares to use it.

Cheers
Tony

 

Why not put a timer on the bilge pump, with a selection switch on the dashboard for OFF, MANUAL, AUTOMATIC.
Normally you should have your bilges empty in 5 minutes (automatic mode). When your bilge alarm comes in again, you know something is wrong and you go to manual.
Just make sure your bilge pump can handle a certain time of dry running.

 

My first thought was, seems like a lot of fooling around for something they already make. A couple of hundred doesn't seem bad for a guy with a 52 ft. boat, seriously, not trying to be a wise guy!

 

There's more to it then you think, like how to keep the pump from endlessly cycling in a sea way as water splashes your probes and other issues you've less engineering experience with. Any pump can clog or burn up with crap in the bilge with or without home made devices attached to them. Start thinking redundancy for key systems.

First of all, seamanship is the key to keeping a yacht. You either pay someone who does it for a living or learn it yourself. Clearly a new craft of any size, with through hull fittings, will need it's bilge inspected very often the first few days in the drink. It's the first thing I do when I go aboard and the last thing I do when I leave, especially on an untested, yet trusted vessel.

I'm completely with Kkimble, in that your investment isn't finished, just because you've gotten a second mortgage and now are the owner of a fine yacht. Let me guess this was one of the options you failed to check off during the purchase, though the upgraded stereo and cushions were? I don't feel sorry for people that launch their boats in the water, with no idea there was a transom plug. What fraction of a percent, would this investment in proper bilge equipment amount to, in the total outlay for this yacht? Maybe it's the idea or principle of the thing, which I can understand, but not at the lose of my vessel to spite a hundred bucks. Just wait until you drop that nice new anchor in deep unexplored waters, just to find you forgot to make fast the end without the big chunk of metal attached to it . . .

 

The only way to keep any pump sucking floor- bilge water running forever reliably is to put several stainless steel wire " baskets "around the pump and use BLACK plastic TY-RAPS to close the top of the opening where they will meet at the power cord. The SS screen should be about 1/16" mesh hole size. 2 layers are a ABSOLUTE MUST to stop string stuff from reaching the impellor. You should unbolt the floor mtg. bolts and put them thru the bottom of the screen. Leave about a foot of screen flat on the floor all around the pump before you bunch it up at the cord..-----------------------what voltage does your pump run on?

 

Assuming the fish line came in with the water. DO NOT run the propellor. There is probably more fish line still in the packing space. It WILL cut the seal and leak again. Have a good mechanic check it for you.

 

If your pump has a separate on/off (i.e.: Float switch) switch you could connect a time delay DPDT (Double Pole Double Throw) relay into that circuit. Use one set of contacts to activate your alarm and use the other to latch the relay. Then wire in a reset switch to disconnect your latching power momentarily to reset the relay. Probably pick up those parts for less than 30 bucks.

If the switch is internal to the pump then I dunno
Maybe you could find some type of current sensing device and use the time delay relay from above.

Good luck

I'd like to see your final layout.

 

A lot of the new 120 vac basement floor pumps have a built in timer and test run circuit that only runs continously if the motor current senses a pump load. Then it runs 1 minute or 2 more to prevent nusience cycling. Great for a boat bilge? Not sure about dc version. Any one interested I still have the paperwork if needed.

 

A second pump and switch mounted higher in the bilge can be rigged. This way it comes on only when the lower pump is overwhelmed. Rigging strainers can be a real pain in the ***, but a necessary evil to prevent just this. Pump manufactures have engineered pumps that can swallow just about anything, but they do cost a bit and still can become clogged or jammed. I've done a lot of offshore sailing and pumps are as important as steering gear. You want a backup system, a easily repaired unit, while the boat is rolling and pitching and one that can be operated in the worst case scenario. BOAT stands for Bring Over Another Thousand in most yachts I've been acquainted with. I don't think this 52 footer is much different.

 

Par. Thanks for my laugh of the day. BOAT

 

Rule -boat pumps, makes a solid state pump that has the 1 minute run after pump out, to stop short cycling. Just 2 wires, - and +12 vdc. I know for sure. I have one in the small fishing boat. It has run for 2 years, no problems.

 

I think the owner of this yacht as well do I, don't like the idea of something cycling on and off without someone aboard. For a runabout or small cruiser this is fine, but a large craft requires better engineering then switching the pump on and off until it can suck on something other then air. I don't know how long it would take to draw down a battery, but it's generally not wise to leave a vessel unattended with electrical devices bleeding off the juice that will be needed to run the pumps if a thru hull tosses it hose or something.

There are systems available to perform the task as well as reasonable installation techniques that can prevent damn near all flooding issues short of taking a torpedo in the belly. He just doesn't like the cost of a motherboard, it's engineering and manufacturing that typically go into these automatic systems, thinking he can do better himself with a homebuilt rig. I wish him luck, but I'll bet his insurance man is wishing something else will be installed.

 

Click on Rule Industries, Bilge Pumps, automatic, read the description of operation. I see nothing unsafe. It has a third lead. + 12 vdc switched to this will start the pump even if no water is present or the sensor has failed.

 

I'm very familiar with the Rule line of pumps. There seems to be several ways to handle the engineering, the one he and I don't like are the ones that cycle the pump every so often then shut down unless the motor gets a load. Personally, I like external switch types. This provides some options in the way the pump will operate and when it will activate. All boats that can travel farther from shore then one can swim back to, should carry multiple pumping systems.

My current offshore boat has 5 pumps, 2 manual and 3 electric plus a "Y" valve, hose and strainer to the raw water intake. In the event all pumps are overwhelmed, or, for one reason or another not up to the task, I can suck water directly out of the bilge with the engine mounted raw water pump, simply by flipping a valve. Maybe this is over kill, but you can only drown once.

 

PAR. Did you get the idea of using the engine coolant suction side as a pump from the 1930 to 1940 Scott- Atwater outboard motors? That was a built in standard feature on them. Before plastic bags were in all waters. Just remember the filter screens to keep the impellor clean. I am talking about the engine water pump. Are you? Or are you a closed cycle?