• Bilge Alarm - Build Your Own Bilge High Water Alarm

    Wouldn't it be nice to be warned if your boat was taking on a dangerous amount of water? While many newer boats have bilge high water alarms installed, chances are if your boat is more than 10 yrs old you are missing this critical safety component. The only warning you may have of excess water in your bilge is the fact that your bilge pump is running continuously. But if your engines are running can you hear your bilge pumps?

    There are several commercial bilge alarms available but if you would like to build your own, this article will explain how. The total cost will range from approximately $30.00 to $50.00 depending on how complext you want to make the system

    Components you will need:
    - bilge pump float switch
    - piece of aluminum stock 3 inches wide x 1/4 inches thick, lenght appx 24 inches
    - 10 or 12 gauge wire
    - rivets or stainless steel bolts
    - piezo buzzer (radio shack)
    - red warning light (auto parts store)

    The basic idea is to make a bracket to mount the bilge pump float switch to that will extend to the desired depth into the bilge. When the water raises the float switch it will complete the circuit and trigger the piezo alarm and illuminate the red warning light. The piezo alarm can be mounted behind the instrument panel, while the red warning light should be mounted in the instrument panel. That way even if the engines are running you should be able to hear the alarm or see the warning light.

    The toughest part of this project is setting the appropriate height of the float switch. On most boats the bilge area is a confined area and a few gallons of water will raise the level in the bilge quite rapidly, but as the water begins to flow from the bilge into other areas of the boat the rate at which the depth of the water rises decreases rapidly. The water is filling up a larger area so it doesn't rise as rapidly, but you are quickly gaining weight. You want your alarm to sound off before this process begins.

    Personally I have a two stage bilge pump setup. I have a low discharge capacity bilge pump in the bottom of my bilge for normal use. I have a high capacity bilge pump mounted appx 1 inch above the bottom of the bilge to start pumping if the smaller bilge pump cannot handle the job. I have an amber caution light mounted on my instrument panel that illuminates to alert me that this pump is running. That way I can determine the source of the problem before it gets out of hand.

    My bilge high water alarm float is mounted to sit appx 1 1/2 inches from the bottom of my bilge, this level is just prior to the point where my bilge water starts spilling over into the remainder of the boat. To determine this takes some trial and error, each boat will be different. I actually took a water hose and began filling my bilge with water until it started spilling out of the bilge. I then inserted my bilge high water alarm float into the bilge and when it triggered the alarm I marked the bracket and mounting location 1/2 inch lower than this point. I wanted it to warn me prior to this condition developing. (I know most people won't intentionally fill their bilge with water but it is an eye opening experiment to see the bottom of your boat filling up with hundreds of gallons of water while the water level doesn't rise hardly any at all).

    Attachment 174

    The picture above shows my bilge alarm. It is mounted to a piece of aluminum stock and fits into the hole just behind it.

    Attachment 175

    This is a simple wiring schematic showing the wiring for the float switch, warning light and buzzer. It is important to wire the warning light and buzzer in parallel and not is series. If wired in series, failure of the warning light would also render the buzzer inoperative. See the diagram below.

    Attachment 176

     

    Comments 22 Comments
    1. kw210's Avatar
      kw210 -
      Great idea,simple and easy.
    1. TimG's Avatar
      TimG -
      thank you, it works really well!
    1. Cap'n Ray's Avatar
      Cap'n Ray -
      Very similar to the one I put together for the old Bayliner and plan for the Carver... It'll wake me up if something goes wrong during the night too!
    1. TimG's Avatar
      TimG -
      yeah Cap'n the only thing I have to figure out is how to temporarily disable it. When I installed it I actually poured water into the bilge to determine at what level I wanted it to go off. The only problem is when we are asleep in the v-berth the forward weight causes it to trigger much sooner and here I am pulling hatches with this thing screaming in my ear. It will certainly get your attention.
    1. Cap'n Ray's Avatar
      Cap'n Ray -
      I'd put a DPST toggle switch on the ground side of the piezzo so when you silence the piezzo you also apply ground to the light so you can't forget to turn your 'silence' switch off.
    1. TimG's Avatar
      TimG -
      That sounds like the way I will go and would definitely help. In the meantime I know they make switches with timers or something of the sort that I could silence and after a period of time later it would arm again. However I haven't found anything that would work yet and of course the price would probably be prohibitive for something like that.
    1. Cap'n Ray's Avatar
      Cap'n Ray -
      Check Fry's electronics website, search for a timed relay. Might be able to get something under 10bucks. Your not workin with huge current or voltage, and the precision of the time is pretty non-critical so you may be alot less expensive than you are thinking! If I get a chance I'll take a look too.
    1. TimG's Avatar
      TimG -
      That sounds exactly what I need and just didn't know what to call it so I could search.
    1. Cap'n Ray's Avatar
      Cap'n Ray -
      For what it's worth Tim...

      http://compare.ebay.com/like/1403837...=sbar&_lwgsi=y

      Just put 12v timer relay in your search engine of choice and watch it go nuts!!
    1. TimG's Avatar
      TimG -
      Thats exactly what I need, you have just added another item to my winter "to do" list!
    1. Cap'n Ray's Avatar
      Cap'n Ray -
      OOPS!!! lol, sorry to create more work for ya, I'm sure you already had plenty :-)
    1. tartanss's Avatar
      tartanss -
      Hi. Just close to what I'm trying to do. I want this alarm to trigger the pump the siren and a light but can't figure the wiring diagram in a failsafe way. Ie if the light fails. Was hoping to run circuit to connect light then siren and also a bypass wire for failsafe and then down to the float to pump. Neg return from pump. Is this possible.
      Any ideas out there.
    1. tartanss's Avatar
      tartanss -
      Hi. This is almost exactly what I want. I was hoping that I could wire from switch to siren to light and then to float. When the float switch connects to pump the circuit back to Neg would be complete. If I also put a loop around the siren and light the pump would still work if either failed. Is this assumption correct.
      Thanks
    1. Roger's Avatar
      Roger -
      I think I get what you're saying. A sketch would help for sure. I'm thinking that you can't wire loads in series like that.
    1. tartanss's Avatar
      tartanss -
      Hi thanks for reply. I would send diagram but I don't see how.
      Rob
    1. tartanss's Avatar
      tartanss -
      Picture of wiring diag of what I thought
    1. Cap'n Ray's Avatar
      Cap'n Ray -
      Nope. Here's the easy way: float switch has two wires, one goes to negative bus ("ground") and the other to the negative side of the pump. Positive side of the pump goes to a fuse or switch with battery positive on it. You can hook a second wire to the negative side of the pump with the wire from the float switch and take that to the negative side of your light and buzzer (you can go through a switch on the way if you want- that would disable the light and buzzer but pump would still run). The positive side of the light and buzzer should go to a fused positive source (fuse buss under your instrument panel etc) that is hot anytime you want them to work (same source as ignition switch or accessories??).

      If this isn't clear, I'll draw a diagram for ya. Just let me know.
    1. madcracker's Avatar
      madcracker -
      all switches use the same polarity, either positive or negative (unless there is a load in the switch such as a light). Generally speaking, most boat dash switches are positive switches, so are bilge pump float switches per ABYC.
      that being said, your idea is a great one and I will use it only reversing the polarity.
    1. Cap'n Ray's Avatar
      Cap'n Ray -
      Double check ABYC. Two comments- The switch doesn't care if it's in the positive side or the negative side of the circuit, it simply opens or completes it. If it has a light, it can still be in either side (unless it's an LED) you just change where the third leg goes. The reason for switching negative is because if your float switch (sitting in bilge water) looses its ability to insulate, you do NOT get a stray current problem (you would if you switched positive). The same can be said for the pump itself, but the electrical portion of a bilge pump isn't usually sitting in the water, but the float almost always is. The fewer sources of positive in or near the bilge water, the better- you reduce all of the nasty risks associated with stray current.
    1. jack's Avatar
      jack -
      Quote Originally Posted by Cap'n Ray View Post
      Nope. Here's the easy way: float switch has two wires, one goes to negative bus ("ground") and the other to the negative side of the pump. Positive side of the pump goes to a fuse or switch with battery positive on it. You can hook a second wire to the negative side of the pump with the wire from the float switch and take that to the negative side of your light and buzzer (you can go through a switch on the way if you want- that would disable the light and buzzer but pump would still run). The positive side of the light and buzzer should go to a fused positive source (fuse buss under your instrument panel etc) that is hot anytime you want them to work (same source as ignition switch or accessories??).

      If this isn't clear, I'll draw a diagram for ya. Just let me know.


      Can you supply a Diagram?Thanks Jack
  • Recent Forum Posts

    TimG

    yeah with them turned down you take a chance of...

    yeah with them turned down you take a chance of them siphoning water back into the system if the engine ever diesels, I think you have it the best way.

    TimG November 8th, 2017, 21:13 Go to last post
    footbrake

    I did try them turned down just below the water,...

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    footbrake November 3rd, 2017, 03:16 Go to last post
    TimG

    I'll be interested to see how they hold up, I...

    I'll be interested to see how they hold up, I would expect they should work fine. You may have a patent in the making....lol

    TimG November 2nd, 2017, 19:25 Go to last post
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