Bilge pump outlet?

[Docpal]

Due to a variety of circumstances( bum leg, lousy launch ramps in area, etc.) I have been keeping Petunia in the water at a local marina. VERY convenient as all I have to do is drive there, and go sailing. I'm on the Toms River which usually has all the wind I'd want (and sometimes more...) every day. And the river runs right into Barnegat Bay less than a quarter mile from my berth.

I'm just about ready to launch her for the season but as I wrap up some last minute details I've been meaning to get around to I have one issue which still has me stuck: since we do get some good thunderstorms throughout the Summer I need to have a working bilge pump standing by. Last Summer I simply ran the outlet hose over the gunnel, but this is not only unsightly,it's inefficient as it extends the length of the hose  a few extra feet. Based on my pump placement (see attached picture) the "ideal" solution for me would seem to just run the hose directly into the centerboard trunk, but I'm still weighing the good vs bad here.

Good points: it's right there,and would mean no more than 12-15"of hose from the pump so I'd get maximum lift/suction not only while at the dock, but also underway.

Bad points : awhile back I believe Graham cautioned me that putting the outflow hose too far aft would risk being affected by the steady stream of water pressure which builds up at the aft end of the trunk (if any of you have ever had a small leak at the aft end you've seen just HOW much pressure than can be....). Another potential problem is that this doesn't leave me a lot of room for an "anti siphon loop" and so it would seem that I could be creating an unwanted path for all of that pressurized water to back flow into the pump.

I thought about running the hose a little further forward but due to the tight tolerances of the board/trunk there really isn't much room inside the trunk to let the water go anywhere, and the aft end of the trunk is where I seem to have the best potential for a clear outflow.

Has anyone else come up with a solution for a similar issue?

[Hirilonde]

Am I correct to assume that the only time the bilge pump needs to be set up is when you leave the boat?  Or primarily at least?  If so, who cares what it looks like, you can't see it once you start heading home.  I would be tempted to use into the trunk or over the side and coil the hose or remove it for sailing.  Bilge pump outlets should be well above the water line.  I can't think of any pretty route from the bilge to such a place for a permanent installation.

[Docpal]

Dave,

 Yes it HAS to be in service while at the berth at all times since obviously the Anderson bailer is then out of play. I did what you suggested last season (leaving it over the side even while sailing) although with the cabin Petunia is a lot drier than most earlier CS 17's.

One change I'm making for this season is the installation of a larger (group 24)  battery. My 20 watt solar panel should keep it charged enough  to offset even a local monsoon. I just thought I might be overlooking a simpler solution, but since the current method works I'll probably stick with it instead of poking more holes in her...

[Chick Ludwig]

When I worked at Irwin Yacht many years ago, a brand new Irwin 50 (I think) sank at the dock from an incorrectly mounted bilge pump. The hose ran directly from the pump up to the boot top. An onshore breeze caused wind chop to splash against the side of the boat where the pump thru-hull was, causing the water to back-flow into the bilge. ALWAYS have a vented loop if your discharge is near the waterline---even when the boat is heeled over.

[Ken_Potts]

I solved the siphon problem on my Red Witch by forgetting about it and putting the outlet way up on the side of the cabin.  The outlet is well above the cockpit coaming so if it ever goes under water we'll already be sinking pretty fast due to the water entering through the companionway.

There is a possibility that water could enter the outlet when the boat is heeled way over but I never spend much time at that angle of heel - Certainly not enough time to fill the boat through that little hose   I've washed the side decks plenty of times (even to the point of putting the cabin windows under) but I don't know if I've ever actually gotten the outlet into the water.

Now that I'm thinking of it, there's a good possibility that if the outlet ever actually does go under water due to unbelievable angles of heel, the bilge pump will probably be higher than the outlet...

[Hirilonde]

"f. The discharge location shall be above the waterline created by maximum conditions of the boat's loading, heel, trim and motion astern. EXCEPTION: The discharge may be located below the waterline if the discharge line is provided with a vented loop to prevent siphoning into the boat. A check valve shall not be used for this purpose."     Exert from ABYC standards for AC bilge pumps

https://law.resource.org/pub/us/cfr/ibr/001/abyc.H-22.1986.pdf

 

I have yet to meet a professional sailor who doesn't advocate to avoid the exception whenever possible.  If you really think it through, the exception is never really necessary though some times desirable.

[Dnjost]

Going rogue here.  How about a good fitting cockpit tent?  Many small one designs use this approach.  

 

If I needed to put in a bilge pump, I would run the discharge line under the center thwart and to a fitting about an inch below the gunwale, and add a vented loop in the locker.  

[Docpal]

David,

 I have experimented with a cockpit cover,using a space blanket type of material strung over wooden battens,which are then suspended by the mizzen boom. It certainly helps with incidental rain,and gives great shade while at the dock, but obviously if I get the thunderstorms in question the wind which comes with them will make short work of this rig.

I'll have to do a "dry run" (pun intended) of discharge hose routing to see if there is any loss of flow by adding an extra bend in the outlet hose. At the moment I have a gazillion last minute jobs to deal with so I can launch her and  the path of least resistance might be to follow Dave's suggestion and just leave things as they are for this season. The attached picture shows the current rig of both cover and hose routing.

 

[PAR]

Depending on the "lift" of the pump, the discharge hose type can improve efficiency by 10% - 30%. The usual corrugated hose is pretty restrictive, especially if the pump has a bit of height and some bends to lift through. A 1,000 GPH pump, lifting 3' might only manage 650 GPH, which is a pretty big difference. Use a smooth sided vinyl or rubber hose, of the appropriate diameter. The same is true of the intake side, if it has a remote pickup or you've modified it to have one (something I do often). You'll get a 10% improvement with a minimal lift (12" or less), using the smooth sided hose and over 30% if pumping the water higher around bends.

 

 

Lastly, don't think that the GPH figures on these puppies means they're any good. I've never seen a 1,500 GPH pump do anything close to this in the real world. I'm talking about the typical all in one units found at the local West Marine or other retail store. These figures should be just used to compare against other pumps of similar size. Most every one of these style of pumps will burn up if asked to pump 1,500 GPH continuously, like in a sudden and violent thunderstorm. A small boat can easily get overwhelmed in these storms (I've seen and bailed plenty), so consider two pumps, one mounted higher than the first, to act as a backup, in case the first pump gets hammered and can't keep up, the second comes on and eases its load. Of course, this is necessary on moored or berthed boats.