Topic: Installing a bilge pump/thru hull questions

Hello all

My co26 doesn't currently have an electric bilge pump and I would like to install one before next season. My thinking on this is that I want a pump for catastrophic failure only, not to remove an inch or two of water of rain water from the bilge, I can do that manually.
A copy of questions;
- Where is your thru hull fitting located and where would you like it to be?
- Can anyone recommend a quality high volume pump? Cost is less of an issue compared to quality/reliability.
- Switch in the pump or external, which do you prefer?

Any other thoughts?

John

2 (edited by Ian Malcolm 2012-09-09 14:27:11)

Re: Installing a bilge pump/thru hull questions

Re: Installing a bilge pump/thru hull questions

I agree. My outlet is on the transom well above the waterline. Another thru-hull below the waterline increases your risk while you are trying to decrease your risk by installing the pump. If you get a big high volume pump, do not forget that you need lots of battery capacity to run it.

Re: Installing a bilge pump/thru hull questions

I wouldn't put another throughhull in the boat -- but if you do, make sure it is above the waterline, with a big loop in the pipe that goes as high as possible. Otherwise, you'll siphon water into the boat. Not good.
My pump outlet goes into the cockpit drain pipe through a T-junction. That cuts the number of throughhulls.
One problem. Most of the standard electric bilge pumps are immersion types. They sit in the bottom of the bilge and there's no way to get a standard immersion pump into my bilge, or out for cleaning, without removing the engine or the prop shaft or the exhaust. You could be into some complicated mechanical work.

Re: Installing a bilge pump/thru hull questions

Bertinol,

I put a "whale super sub pump 650" into the bilge, the pump is small enough to use thes access near the prop shaft. This pump as is own switch. I clamp the hose on the hull by gluing somes pieces of wood with 3m 5200, on the pieces i screew a clamp. the exaust of the hose is in the high of the transom.


Marc

Contessa 26 #158
Sun Wave
Montreal QC

Re: Installing a bilge pump/thru hull questions

Thanks for all the replies, good food for thought. At this point I think  I will install a thru hull high up on the transom. I considered T'ing into the cockpit drain pipe but am concerned about the fact that when healed over the drain is below the water line. Any thoughts on this?

John

Re: Installing a bilge pump/thru hull questions

Yes, don't do it!
Consider the scenario:

You are on a long beat to windward and that cockpit drain is continuously immersed on one tack.

The bilge pump starts itself due to the water level and promptly fills the hose with water.

After emptying the bilge, the pump gurgles to a stop, but   the hose is full of water and the outlet is immersed so it starts back syphoning and as the bilge fills, starts again.

You hear the pump short cycling and guess its float switch is jammed so turn it off (or some hours later the battery fades, or even the pump fails)

Now the pump back syphons till you notice the cabin sole awash, or even till you sink.

Also, how much down on your marks would you have to be for the outlet to be immersed with the vessel upright?
A simple cockpit party could be enough to start the trouble if a few extra guests drop by.


If you must install a pump to a (potentially) below water through hull, a vented loop is essential to break the syphon.

Re: Installing a bilge pump/thru hull questions

This is an interesting discussion....

Ian:
How about if the cockpit drains cross over to the high side.
And, the bilge pump hose goes as high as possible under the gunwale in the centre of the boat -- way above the water line.   
A vented loop is a good idea too.
So are doubled stainless steel screw clips. A lot of them have stainless clips and carbon steel -- ie rusty - screws.

By the way, the first thing I did on my 1975 Contessa was to install seacocks on the cockpit drains. I later discovered that many of the older boats never had seacocks (Help!). I also replaced all the Canadian Tire bathroom fixtures that a previous owner had used as seacocks elsewhere in the boat.
Proper seacocks are a good idea!

Re: Installing a bilge pump/thru hull questions

Why complicate your life?

T'ing it into a cockpit drain requires an expensive bronze barbed T fitting (as its potentially below the waterline) + an expensive vented loop, that must either be maintained annually (basically just unscrew and wash out the rubber air inlet valve - but access will be a stone bitch)  or have its own vent hose and vent fitting.   

It adds three extra joints to the drain to increase the risk and also, if the reason you are running the pump is a split cockpit drain, shutting the seacock will stop you getting rid of the water!

Well above the waterline with a simple plastic through hull with no seacock is cheap, doesn't compromise the cockpit drains and will give you better flow than anything that has multiple joints or fittings in the hose.

My JR Contessa 26 has three 1/2" cockpit drains to the bilge (non-self draining cockpit) and a 1 1/2" drain straight out through the transom from about 6" up the rear of the cockpit with a non-return valve, that is supposed to help if you get pooped.   There is not really enough room to fit a seacock + the angle is virtually impossible and access to operate would involve relocating the gas locker, but as the drain is well glassed in 2" copper pipe up to the valve, I don't worry much.  Unfortunately wave action 'burps' the valve and if there is any fine floating debris or even weed about, it can jam the valve open so I keep an expanding rubber dinghy bung in the cockpit end through hull fitting except in heavy weather.

Cockpit drain seacocks are GOOD, but its use them or loose them.  If you dont operate them weekly or at least whenever you go to the boat, they are likely to be seized when you most need them.  You also should have a good supply of tapered bungs easily accessible or even taped to the hoses in question. Bungs should be chosen to have a small end that suits the fitting and a large end that will still adequately block the hole if the whole fitting has sheered off and the flange dropped out. Tied on with a lanyard is a PITA as it is one more thing you have to undo if the lanyard is short, and if its long the bung is likely to have floated off somewhere awkward and jammed out of reach.   Give me a couple of turns of tape you can twist loose any day!