Almost Sunk my Power Catamaran

[Jim Hawkins]

Yup, almost went to the bottom of the canal from a bilge pump malfunction, here's what happened...

The boat is a 1997 Catamaran by Nautico/Seagull. Inside both hulls are bilge pumps with automatic switches. When one turns on the other does too. They are accessed by two round ports near the stern of the boat. The boat was new to me and I was still learning about the systems including the bilge pumps. When it rained I had to go out and manually operate the pumps with the switch on the console, the automatic switches weren't working.

Trying to figure out the problem I found one pump had a mechanical switch, the other an electronic switch. In the course of fiddling with them the one with the mechanical float switch began to work and as they are 3 wired they can either come on automatically or with a switch on the console. As I said, when one comes on it is wired to turn both on. OK, so here's how it happened. The boat was leaning slightly to one side (the side with the non working switch) and it began to rain. Since the boat was leaning the rainwater naturally ran more to that side. This increased the pressure for water to leak into that side hull...and the boat leaned more, and more. Finally, the upper side hull got enough water in it to operate the pumps BUT since there was less water in that side it quickly pumped that hull dry and left the other still full now with the boat leaning hard and rain coming down in buckets. Now the angle was so steep that all the rainwater ran to the lower side and had only another couple of inches to go before the water started pouring in.

I had been home the whole time and watching it to see how the bilge pumps performed. I looked out and saw the boat sitting what appeared level and no water above the deck. It continued to pour rain and less than 10 minutes later when I looked again I saw the boat leaning so hard over it was ready to sink. I ran out, and getting into the boat on the high side to help level it I turned on the pumps manually and began bailing like a madman. I was at it for about 20 minutes with the rain coming down so hard I could only keep it in check before I finally got it under control.

So, I've been reading and researching bilges and switches and have read that pumps fail far less often than the switches and the switches are almost universally problematic. I'll be posting a thread on my repairs but the gist is, after sealing up the deck to slow water penetration I will install 3 new pumps with automatic switches all switched together. 2 will be in the hulls and the third will be in the center hull. This cat has a very small middle hull that runs half the length of the boat and is only several inches deep and several wide. It also seves as a chase for wiring etc running from the console, under the deck and back to the motor. Instead of sealing this off, I am cutting the deck to open it up to use with a 3rd pump. This will catch all the water from the upper deck before it can get to the outer hulls. And, that 3rd pump will have an additional backup switch.

 

[GA_Boater]

Why do you want to control three pumps with float switches in parallel?

If the wrong one fails or jams, the pumps won't turn on until the center hull fills enough. The proof is almost sinking your cat at the dock. If you want redundancy, put two float switches in each hull, but not controlling all three pumps.

 

[Jim Hawkins]

""Why do you want to control three pumps with float switches in parallel?""

Because here in S Florida, when it rains, it pours and if one comes on, why not all three?

""If the wrong one fails or jams, the pumps won't turn on until the center hull fills enough. The proof is almost sinking your cat at the dock. If you want redundancy, put two float switches in each hull, but not controlling all three pumps.""

With the pumps and switches all wired together if any one of 4 switches closes all 3 pumps will turn on.

 

[GA_Boater]

What if the low, filling up hull has a failed switch? The two high and dry switches aren't turning on any pump until the boat is slipping under the waves - Exactly what almost happened already.

 

[Jim Hawkins]

GA_Boater, just when I have my problem all worked out you have to go throwing common sense into the mix. I suppose all three should be wired separately and double switching the pumps in the hulls would safeguard against a switch failure but not a pump failure. I wonder if I could have the lower hull pumps also trigger the upper deck pump (in the middle) without the upper pump triggering the lower pumps. That way if one hull was dry and the other full there would still be the upper pump to keep the water in check although still listing.

 

[Jim Hawkins]

Update: Turns out all 3 of my pumps with built in switches work. The main problem seemed to be the installation and wiring. So, I tore everything out. Bought new 3 conductor, marine grade tinned wire and each pump will operate separately and will have it's own new wire as well as manual and automatic switching. All new connections Soldered on and coated with liquid electrical tape stuff.. The upper middle pump which I recessed into the center hull as a bilge well seems to be working great and the lower pumps should never have to work if all goes well. Yes, I'm knocking.
Oh and, thanks GA_boater

 

[GA_Boater]

YW. Jim.

Sounds like you got the mess fixed up now. You should have peace of mind with the next heavy rain.