Bilge pump discharge location

Stu Jackson · Nov 21, 2010

Yes, downside is an underwater drain. Why not consider adding another thru hull above the waterline?

Stu Jackson · Nov 21, 2010

Any underwater thru hull should have a seacock on it. Even my C22 had one! Just another level of complexity.

Ed Schenck · Nov 21, 2010

Stu, he does have a seacock on his scupper hoses. But I still agree that it is best to run the bilge hose to a separate thru-hull through the bootstripe. Not sure that a 'T' would be a problem though. I don't think scupper water could get back through the pump to the bilge. You sure would not want a check valve.

Roger Long · Nov 21, 2010

Prime Time said:
What is the downside to the underwater drain?

Look closely at the rules again. I don't have a copy but it wouldn't surprise me a bit if they say the discharge must be above the waterline. If it's below, you should close it every time you leave the boat and you are apt to forget to open it since it may never be used. When that do or die pumping situation arises, you may not be able to leave the helm or have anyone capable of finding and opening the seacock. A person in a panic might break some pumps trying to pull against a closed seacock. That probably wouldn't happen with an anti-siphon loop valve but they might pump away moving air through the lines thinking the great resistance of the small air valve meant they were moving lots of water. With a below water discharge, there is no way to verify that water is actually going out.

Roger Long · Nov 21, 2010

Prime Time said:
I have deck scuppers that drain below the waterline via seacocks.

I'm sorry to hear that. Maybe it's just a superstition but I never leave any seacock open when I leave the boat. I relocated my cockpit scuppers above the waterline for this reason.

Even though a below water discharge might not be prohibited by the rules, I would put a new through hull in for the reasons I gave. If you are pumping to save your life, any water pressure restriction becomes important. Chances are you won't be level but, if you have to be on a tack that puts the discharge under, every bit of depth reduces the amount of water you can pump.

Another thing about below water cockpit drains, debris go down them, float on the water surface, and then trap more debris until you have a plug. Rain water may keep draining and you won't realize that the draining capacity has been seriously reduced until you take a wave and are waiting for the boat to relieve itself of the weight of the water in the cockpit.

Roger Long · Nov 21, 2010

Prime Time said:
http://www.fastflowpump.com/

That's on my list of the 10 best boating ideas ever. I wish I had the shaft clearance for one. It might have a chance of keeping up with the kind of damage something like a floating container might do to a fiberglass hull. The fact that it can move air and be a blower when not moving water is very cool.

DianaOfBurlington · Nov 21, 2010

I did not see this made clear in the ISAF rules being cited, but the 'unspoken' rule is that NO bilge pump expected to be used for emergencies (and what other kind is there?) should ever share a through-hull with any other fixture or drain. Every bilge pump should have its own dedicated through-hull, switch, fuse, seacock, handle, and so on. If you happened to have three pumps the idea would be that all three could be operated independently or together, at the same time, with no interference.

I would NEVER rely on a bilge pump that had to drain into a cockpit and thus rely on the cockpit drains. What if the cockpit drain were the source of water coming into the boat? --and this is probably very likely. Ditto for an on-deck discharge that relied on deck scuppers.

Having a side-located through-hull for a bilge pump becomes a problem when the boat is heeled. This is why ISAF suggests a cockpit drain aft. If there is no vented loop in the discharge line, the discharge through-hull will suck rather than drain. One should make every effort to drain the pumps as far aft (and parallel with the centerline) as possible.

Especially for a very long (hopefully straight) discharge run, you can fit a check valve in the line, at the highest rise which should be immediately after the pump, to avoid the hose-full of discharge line draining back into the bilge when the pump shuts off, thus activating the float switch again and kicking the pump back on over and over till you become annoyed and turn it to 'off' or the pump burns out and/or battery dies. There should be no unnecessary dips, corners, or rises in the discharge line. Try to make the run beyond the highest loop drain downwards on its way out so at least out of the water the hose will be empty. I would NOT recommend PVC pipe for this, only the rugged Shields 148 holding-tank hose (or its Trident equivalent).

There are plenty of 'creative' ways to dewater a boat. These have been used throughout the ages. One is a Y-valve on the engine intake that allows it to suck water from the bilge, not the sea. This is for emergencies only, obviously. The nightmare I heard of was a boat striking something-- it went down in about 2 minutes. Someone on board had the presence of mind to start the engine, which probably added a minute to the abandon-ship time. The boat went down with the engine running... but that engine saved lives.

You can do the same thing with a deck-washdown pump.

Another idea is to have a large (2"?) drain plug towards the bottom of a gray-water or holding tank. Pull the plug, let the tank flood, and use the pumpout pump to assist the bilge pump.

You can do the same thing in an emergency by discharging a hand pump into the sink.

Every electric-only pump should have a manual backup. To my mind (and in my boat) the Whale ones are the best manual pumps in the world (Royal Navy spec). The double-diaphragm design ensures at least half the power even if one side breaks. Some of them are almost as efficient as an electric one.

In going to sea (and for the same reasons when leaving a boat for long periods at a dock) a backup electric pump is key. At CY we conceived of the 'bilge pump on a stick' --not a robotic delicacy but the pump and float switch mounted on a long plank and lowered vertically into the depths of the bilge so as to be easily accessible-- just unbolt the top end of the stick and withdraw the whole arrangement. The C44s get TWO bilge pumps on a stick, one about 6" higher than the other. A red light on the panel comes on when the second one kicks on, indicating that the first one failed and there is 6" more water than usual in the sump. Then when you carry a spare, you've got it covered. Those Rule pumps are actually very cheap-- too cheap to rely on 100% and too cheap to not carry spares to sea.

The last Cherubini 44 we built had 7 different, simultaneous ways to dewater the bilge-- and this on a hull that is renowned for NOT leaking (only a seacock failure or hose failure can admit water below the waterline; the boat is too rugged to crack and has no keelbolts to leak). Dewatering is not an issue to take lightly because you will only find out the true inadequacy of your pumping situation when you would really like to find it works above expectations... and if it does not, it's too late for it to matter.

Roger Long · Nov 22, 2010

you can fit a check valve in the line, at the highest rise which should be immediately after the pump, to avoid the hose-full of discharge line draining back into the bilge when the pump shuts off, thus activating the float switch again and kicking the pump back on over and over till you become annoyed and turn it to 'off' or the pump burns out and/or battery dies

This almost never works and is a source of line clogging. Bilges are full of stuff and a bid of debris will quickly lodge in the check valve flap. This will slow the back flow which may keep the cycling slow enough to let you come back to the boat and find your battery still alive but you will still be stressing it. You'll also probably be woken up by the pump running in the middle of the night.

Bilge pump lines (at least up to the siphon break) should always have less volume than the sump volume that will trip the float switch. This is at odds with the desirability of having the largest and least restrictive line possible. It's also at odds with having everything drain to a small secondary sump so that the bilge can be nearly completely dried out.

The answer is a small pump with a small capacity line to deal with the usual water intake like condensation, ice box melt, and stuffing box drips. The smallest pump you can buy will usually work for this. Then, put your "save the boat" pump(s) a bit higher up so they only get wet in case of unusual water intake. Keeping them dry will extend their life and you don't care if they cycle in the events where they will operate.

Check valves can be used and are useful on self priming pumps that are operated frequently, such as on leaky wooden boats, since the check valves will usually hold enough water to shorten the priming time and will make it easier to get flow established even if dry. These pumps will usually suck debris through a check valve flap, unlike centrifugal pumps that will choke at the slightest restriction.

Herrick18911 · Nov 22, 2010

Free flowing bilge pump

I think that a bilge pump should pump to an above the waterline thru hull for several reasons:

-You will be able to confirm that it is pumping and see the results.
-You will see if there is fuel or poop in the effluent to assess what problems you have in the bilge.:cussing:
-There will be less resistance to the pumping since you will be emptying into the air and not water. Pumping will be easier and more effective.
-Less chance of water flowing the wrong way.

My thoughts.

Tod

PJludlow · Nov 22, 2010

Manual Pump

I carry an Edson high capacity diaphragm pump mouunted to a plywood base that can be held by one's foot while pumping. Edson offers one configured this way. The pump is fitted with quick disconnects and 2in hoses about 20 ft long each. The suction is fitted with a bronze strainer and is naturally weighted to be dropped into the cabin or bilge. The pump discharge can be directed overboard from the cockpit and lashed to a stanchion if necessary. The pump has a long handle making the pumping easier and intrrinsic to the diaphragm pump are two check valves. It's the most dependable pump I have aboard and not dependent on electrical power. No drilling, routing or mounting. Easily inspected and serviced.
Other replies already address the disadvantages of tying in to existing drain lines. However for a manual pump, you don't want to discharge below the actual water line as you will be pumping against the pressure head at whatever depth the boat has settled to, reducing the rate of flow.

Prime Time said:
To comply with the ISAF rules, I need to have a manual bilge pump that I can operate from the cockpit with no lockers open and not discharging into the cockpit or a cockpit drain hose.

My center cockpit design makes this a bit of a challenge. From inside the cockpit, the only access to the bilge is from the floor of the cockpit straight down into the engine compartment. I can install the pump on the vertical outside surface of the side of the cockpit and get access from an interior locker to run the hoses. For simplicity, I am thinking about taking the output hose to a deck scupper drain hose that goes to an underwater thru hull with a seacock. I would not need a siphon break because of the open deck scupper.

Can anyone think of a disadvantage of this layout?

Plumper II · Nov 22, 2010

I agree with Tod.
I also wonder what would happen with your proposed setup if the below the water outlet got blocked (for whatever reason) and it rained hard. Would the scupper drain into the boat?
I like to see what and how much is coming out of the outlet. Back pressure just lets you know the pump is working. I was once pumping water from the bilge to the bilge because of a broken hose. You need to see it leaving the boat.

Gary

Guy D · Nov 22, 2010

I wouldn't tie it in to a scupper drain as scuppers are notorious for acquiring debris. And there's a better than even chance that it'll be plugged where you tee'd into it with the bilge pump discharge as the tee makes for a nice place for things to lodge. Even were the blockage below the tee and the water flows out the scupper, you're adding head pressure to the discharge and, in the case of a hand pump, that head pressure translates into greatly increased effort in pumping. I know that you're trying to satisfy a rule requirement more than adding a safety feature per se. I'm of the opinion that if you're going to put one in it's worth the extra effort to do it in the best possible way....just in case you need it some day.

All bilge pumps should be discharged through an above water discharge port and, if not through the stern, consideration should be made to discharging both port and starboard (using check valves). Sailboats founder far more often than power boats and there's every chance that when it does happen the boat will be either heeled or listing. If the discharge is underwater there is no pump that is not going to have it's efficiency compromised by head pressure. Discharging through the stern and above the waterline alleviates these concerns.

It's become a mantra to not use check valves on the bilge pump and I think it unwarranted. Putting a vertical loop in the discharge is a fine solution, as long as you never leave the dock. If the discharge is through the side of the hull and not the stern the loop may well be ineffective when listing or at large angles of heel.

Debris lodging in the check valve is always cited contraindicating check valves. I think that that concern ignores that the pump has a strainer or strum box around it's suction which will plug first and the pump's impeller will be fouled long before the debris gets to the check valve. Most anything that passes through a strainer box and a pump impeller will pass through a check valve. I advocate using an over-sized check valve, ie...1" hose going into an 1-1/4" check valve bushed to 1". I strongly favor spring check valves made of bronze over swing check valves of any type. The only type of swing check suitable is one with an externally visible pivot, some are even counter weighted, and I know of none of those in a size small enough for boat application. Swing checks leak without back pressure and they are notorious for sticking, especially when not exercised regularly. They also have to be installed properly to function, ie...with reference to gravity. In spring check valves there is no better made than that by Maas-Midwest. A 1" or 1-1/4" is going to run you about $50 retail but they're all bronze and the poppet is also bronze and of a caged design; it cannot come adrift and plug the discharge pipe. I'd avoid similar looking ones with plastic poppets. If the Maas-Midwest is too pricey, Flomatic makes a decent valve, albeit with a plastic poppet. Under no circumstances would I waste my money on any check valve made by Simmons; they self disassemble themselves internally seemingly minutes after installation.

If you're not going to use a check valve you probably ought to have a seacock on the through hull regardless of location. There's only three things that can happen with a hole in the hull, and two of them are bad.

It's always best to fit the largest pump reasonably possible, particularly on a smaller boat (they fill up and sink faster for a given size hole!). No pump is going to keep you afloat from a holing but a big one may give you extra minutes that may be life-saving.

pogo2 · Nov 22, 2010

Whale pump

On my Newport 30, 1987 there is a whale diophram pump located just under the control panel on the port aft side of the cockpit. It is connected to a Yvalve so I can either pump out the Ice box or the bilge manually, the pump is high and resdeded into the cockpit bulkheait and runs to a thru hull in the stern above the water line. I have been in 8-10' following seas and have never had water back up in to the bilge or ice box. Although I keep it turned onto the ice box, mainly to remove the melted water, and have 2 automatic bilge pumps on the bilge, God for bid you take on enough water to say

"wish I had put in another bilge pump" or some thing close to that. the reason for the second bilge pump.