How many bilge pumps?

[MicHughV]

Some many years back (in my neophyte years)....I was on the ICW heading north, when I came to a drawbridge that had restricted times openings due to heavy vehicle traffic.

Unbeknownst to me at that time, the retaining bolt holding the prop shaft inside the flange coupler had worked loose and had fallen out.
Coming up the bridge, I had to jockey back and forth a few times until the bridge opened.
During a " reverse" moment, the entire prop shaft backed out, of which I was quite unaware. A few moments later I engaged forward, but nothing happened. I heard the engine spool up, but no forward motion ensued.

I ducked below, to spy a 1 1/4" column of water hosing down the inside of the engine compartment. By this time, the wind had also blown me sideways, and I was aground.

In a panic I donned a dive mask and went over the side. I don't know what I was hoping to find, as the visibility was close to zero.

Thru' sheer luck, the shaft had backed out of the stern tube, but the tip was hanging by a half inch or so on the rear cutlass bearing. Another 50 rpm on the engine and it would have been gone.

With my last remaining breath, I shoved the shaft back in, where mercifully, it went back in in one go.

Tragedy averted. I spent the next eight hours or so on a falling tide whilst I pondered my dumb luck.

What amazed me was the flow of water coming inside the boat. It looked like a fire hose. I don't know how I would have plugged it from the inside. A tapered wood plug maybe, which I didn't have. No bilge pump would have equalled the flow of water coming thru' that hole.

I am testimony to the that fact that the good Lord looks after drunks, fools and sailors.

It goes without saying, that since that time, I've taken extra care to ensure there will not be repeat of that occasion.

[rslifkin]

Originally Posted by MicHughV

What amazed me was the flow of water coming inside the boat. It looked like a fire hose. I don't know how I would have plugged it from the inside. A tapered wood plug maybe, which I didn't have. No bilge pump would have equalled the flow of water coming thru' that hole.

Depending on the depth of the hole below the surface, you might be surprised. The math says a 1 1/4" hole 3 feet down will give you about 52 gallons / minute (3120 gal/hr). That'll make a heck of an impressive geyser, but even de-rating the pumps by 50%, a pair of Rule 3700s would keep up with that easily. Certainly for long enough for you to find a way to reduce the flow.

[DeValency]

That's probably the horror story we are all afraid of. Yes, we need to remember that any bilge pump, number of fixed bilge pumps or even an added 1/4HP emergency pump, as I have, will not drain such inflow. Actually maybe you were lucky you have been grounded in the ICW, as the inflow pressure was lower than a full displacement...

Apart from the obvious lessons learned which we all need to remember at our weekly/prior to passage checks, this case wouldn't happen where the rudder (or better, the skeg) is close enough to the prop. I can add that when serving the drivetrain (CV Shaft/Joint, Thrust Bearing and couplings, although my skeg wouldn't let the prop shaft pulled out of the stuffing box, I always tighten a hose clamp over a split hose on the shaft, to eliminate more movement than needed for the service - just in case...

[Cynara]

All good points

[MicHughV]

I don't recall how big my bilge pump was at the time, but it was likely a very small one.

I have since gone to great lengths to ensure all the flange bolts are wired together as well the shaft retainer bolt. Besides wire, I also have a small hose clamp on it, such that the tang bears against the flange preventing rotation. On top of all that, I have a larger hose clamp around the entire flange to hold that bolt captive. In addition, I have another hose clamp set at 180 degrees from the first, holding a nut at 180 from the bolt so as to " balance" everything out a bit.

As above, I also have another shaft zinc on the shaft just behind the flange coupler.. to prevent the shaft from disappearing again.

Overkill, nah.....paranoid...probably..

I now make it a habit to peer inside the engine compartment at 30 minute intervals or so to check up on things....

I sometimes wonder why boating is considered fun ???

[alitaptap]

All good points expressed above. #2 is valid but I would double or maybe triple the expected volume required depending on the depth below waterline.

But, from experience, one other thing you simply must do is check what is stored within reach of ingress below waterline.

On an entertaining (euphemism) San Fernando Sea Race (1993), out of Hong Kong, aboard a 47-foot ferro-cement yacht we were all (four) on-deck watching the horizon, other yachts, waves, dolphins, etc etc and nobody realised that there was water coming in through a forward facing window coincident with each wave over the bow (waves were every 14 seconds over the bow) as we beat into a force 6 weather front.

It was my meal-duty so I went below and found the cabin was awash. The two 2000gph electric float-switch bilge pumps had failed, tripped circuit breakers. Immediately I requested the manual whale pump in the cockpit to be used but after five minutes that stopped working too.

Buckets were the order of the day. 400+ buckets of water over the side counted until the weather eased and the waves stopped crashing the foredeck.

Analysis of the cause of the various pump failures were: (a) we had stowed canned goods below waterline so when the water rose as the yacht heeled the labels peeled off as water drained into the bilge - the mashed paper clogged the automatic bilge pumps; and, (b) half of the hook of a plastic coat-hanger (nobody could remember having one) had been sucked up into the manual whale pump and had jammed open the valve so it could no longer suck.

Moral of the story: never store goods below waterline (calculated at extreme of heel angle) with paper labels, instead label cans (and other containers) with permanent marker pen and remove paper labels; before any adventure always, thoroughly check the bilge and any pathway into the bilge for foreign objects; before heading out, practice dismantling the manual bilge pump to check for obstructions; and, make sure everyone aboard knows how to use a bucket.

[gwoiler]

Follow up to my original post.
After cleaning up the bilge and sump, there is a failed pump switch down there. It is wired in parallel with the RULE white lever switch, higher up, which is in one of my past pictures. It was interesting to see an inline brass check valve on the bilge suction hose. Of note is - there are 3 hoses going in to the bilge sump. One is the working diaphram pump, and one is the cockpit manual hand pump. I am wondering what the third hose is for? I did not have time while there to trace it out. It is a small sump! I am not sure which pump auto switch to put down there.

[DeValency]

Is the failed pump senso the black electronic rule sensor? These are usually perfect and bullet proof, I use two of these plus one Water-witch - but note these are sensitive to oily residues in the bilge and anything that holds moisture (that will create a continuous positive sensing) or oils around, such as the tie wraps around - so insulating the sensor from water sensing... They need to be cleaned, as well as the entire bilge, frequently.

[gwoiler]

Originally Posted by DeValency

Is the failed pump senso the black electronic rule sensor? These are usually perfect and bullet proof, I use two of these plus one Water-witch - but note these are sensitive to oily residues in the bilge and anything that holds moisture (that will create a continuous positive sensing) or oils around, such as the tie wraps around - so insulating the sensor from water sensing... They need to be cleaned, as well as the entire bilge, frequently.

I have no idea what that black sensor is other than it is failed. The RULE I mentioned is seen here in this picture. Maybe, this is not a RULE? It looks like one.

[DeValency]

My mistake. - the black box you see is in fact a Whale sensor and is considered very reliable if kept clean
Whale BE9003 Electric Field Sensor Switch, 12V or 24V, Suitable for Up to 20 Amps https://www.amazon.com/dp/B00N4X2DWS...4C0M18QEB0NATC

[gwoiler]

Originally Posted by DeValency

My mistake. - the black box you see is in fact a Whale sensor and is considered very reliable if kept clean

OK. Thank you for identifying this! At $52, I will see if it is possible to clean this. My bilge was filthy. I have no idea how long this has been failed. It was not checked during sea trial. I did notice, as the sailboat was on the lift, and being moved after sea trial, the pump was coming on and off. I was walking next to her and observing intermittent water pumping out. I was wondering if water was traveling in the bilge? If the level was as high as the second level switch, it makes more sense that travel movement was changing the static level as there seems to be passage ways for water to flow from one bilge to another.

[AWT2_Sail]

According to my pre purchase surveyor, ABYC says bilge pump capacity should be 150 gph/foot According to that you should have 6000 gph total capacity. I’ve heard others say one smallish and one larger, probably plus the shower sump.
My ‘77 Pearson 10 m had a grand total of 210 gph capacity, but that one diaphragm pump didn’t even work. Thankfully she’s basically dry.
I’m working on installing a 1100 gph low profile primary and a 3700 gph secondary wherever I can fit it. A little too tall for the 10m shallow bilge. Maybe the engine compartment. Both are seaflos and use water witch solid state switches.

[GordMay]

Originally Posted by AWT2_Sail

According to my pre purchase surveyor, ABYC says bilge pump capacity should be 150 gph/foot ...

IIRC, ABYC is silent on bilge pump capacity [GPH].
ABYC standards and recommended practices [‘H-22'] apply to all boats equipped with DC electric bilge pumps operating under 50 volts intended for control of spray, rainwater and normal accumulation of water due to seepage and spillage. This standard does not cover pumps intended for damage control.
Bilge Pump Rating - Bilge pumps shall be rated in gallons per hour versus heads at zero and three feet at design voltage. Positive or semi-positive displacement pumps shall also be rated at the maximum suction in feet at design voltage. Capacity and head may additionally be stated in SI units.

[DeValency]

Originally Posted by gwoiler

OK. Thank you for identifying this! At $52, I will see if it is possible to clean this. My bilge was filthy. I have no idea how long this has been failed. It was not checked during sea trial. I did notice, as the sailboat was on the lift, and being moved after sea trial, the pump was coming on and off. I was walking next to her and observing intermittent water pumping out. I was wondering if water was traveling in the bilge? If the level was as high as the second level switch, it makes more sense that travel movement was changing the static level as there seems to be passage ways for water to flow from one bilge to another.

Well, you are going to spend much more than $52 on a boat mainenence… and you don’t check water in the bilge by listening to your pump but by opening all the floor boards - ALL - including those normally not opened... Check the situation everywhere, trace any moisture, clean the bilge thoroughly and dry it until your Navy Ship Sergeant “can eat from the bilge”. Make sure also the pumps and sensors are perfectly clean. And then start checking how they function by controlled flooding of the bilge in multiple areas by hose and fresh water.
That’s in the first chapter of seamanship - in fact, has nothing to do with sailing or cruising… 🙂

[Sailorman97]

I have 4. 1 small maintenance pump to keep the bilge dry. 2 2,000 gph and 1-3700 gph. These 3 pumps likely not pump much more than 3-4000 gallon per hour in real life.

The chart below which can be found here

Flooding.html

shows how fast the water comes in.

A 1.5 inch hole 2 ft below the water would overwhelm my pump system. Any blue water boat should have very loud bilge alarms that go off if water gets above the nuisance level. The bilge pumps will not save the boat. They only give you time to save the boat. In order to save the boat you need to know where the water is coming in and you will not be able to find that if the water is too deep before you notice that you are sinking.