I'd like to understand why Ultima bilge pump should be level

[Sunbeam]

Hi folks,

So, I bought two of the Johnson "Ultima" 600 gph bilge pumps, one for the "sump" near the transom drain plug, and the other for the "side bilge sump" that is between the galley and the cockpit on my era 22 Cruiser (2002).

Because of the shape of the hull, this "side bilge sump" is angled athwartships. This didn't really concern me until I sat down to read the pump instructions and they specified that the pump should be level on the exact plane where my hull slopes there. I had planned to install it with the outlet elbow facing outboard, which would make for an angled pump, not a level one.

Now, that being said, there are a few other things in the instructions that I'm not following, but on those I'm comfortable with it because I understand why they are saying what they are saying, and also why I'm not doing what they say (mounting it on a 3/4" piece of plywood, screwing it into the hull, etc.).

I could level the pump on a wedge, of course, but I really don't want to unless I have to. If I understood why they are requesting it to be level, then I could figure out for myself if I need to adhere to the letter of the law, or merely the spirit of it, and/or what I would be giving up if I ignored it altogether.

This is the style of pump that has two sensor pads on one end, and the discharge on the other end (i.e. a built-in switch). I suspect it has something to do with that but I don't understand it enough to figure out what it is.

[Edit: In thinking about this more, I think I can maybe see why it shouldn't be mounted in *one* of the un-level dimensions. Maybe if the sensor pads were "down" (how I was going to mount it, actually), then they would be in that last little bit of water and telling the impeller to pump water out, but the impeller would be "high and dry" and so there would be an endless loop of dry pumping. On the other hand, that only explains why the sensors should not be low, and doesn't cover the other three ways for the pump be un-level, which are also not recommended. You'd think if that were the case they would say "don't mount pump with sensors below impeller." Argh, why can't they just explain the basic concept for those of us who would like to better understand it (btw, I did check the website but didn't see anything helpful).]

Here is a photo of the pump with my notes:



Thanks to anyone who can help me to understand this,

Sunbeam

[rogerbum]

I think you already know the answer - e.g. that the sensor will be lower than the pump impeller and thus the pump will continue to run even when it's not fully able to pump water. As an aside, if I was replace the 500GPH Rule pumps on a 22, I'd put in 1100GPH pumps as opposed to 600GPH. 500 or 600 GPH is really not that much pumping capacity in the rare occasions where you really need it.

[Sunbeam]

Thanks for your input, Roger.

I agree about what would probably happen if the sensor were lower than the impeller; but then that doesn't cover the other directions, e.g. if the sensor was above the impeller. They say merely that "it has to be level," not that "the sensor should not be below the impeller."

Do I sound irritable about it? Or did I mostly manage to hide it The thing is, I don't mind simplified instructions for people who just want "the answer"; but I just wish that they would also give some idea of the concept, too, for those who would like to understand it. It's like when they say to only store a four-stroke motor on one side. That's great information for people who just want to know what to do; but then I'm glad they also explain why, because I like to know that sort of thing (and the base concept has been useful for me over and above the "plain instruction").

Anyway, I could easily have mounted it at an angle with the sensor above the impeller, by turning it 180º; but since they only said "it has to be level," with no details about "how level," or "in which planes," I went ahead (with some grumbling, as you can imagine ) and made three little fiberglass wedges, which I'll bond to the bottom of the sump before mounting my studs. The pump shall be level!

(BTW, the sump slopes at around 9º for anyone who would like to know.)

Sunbeam

[thataway]

"Level" is when the tiny air bubble is in the center of the liquid filled dome... in other words levee in all planes. We "level" our RV because of an absorption refer--it is within one or two degrees of absolute. I suspect that is plenty for this pump.

However, There is always residual water in a sump or bilge where these pumps are used.

Are you mounting this in the center of the boat? That is where most of there are--either aft of the aft cabin bulkhead or forward of the aft aft cabin bulkhead. In our 1992 boat there was one bilge pump aft by the drain. in our 2006 boat there is one, just inside of the door, but with a hole to the bilge in the cockpit. We added a second bilge pump in the aft area, sump, by the drain plug, so that when running, and water got into the cockpit it would be pumped out by the auto switch.

If you mount the pump to the side of the boat, and I don't know if you do, then the switch is moot, unless there is about 4" of water in the cockpit.
In the center , it does not take much to make a sump, or shim it to level.

Maybe I am missing something here.

Why have a auto s

[Sunbeam]

I probably could have explained it better:

I've seen three different ways that C-Dory handled the bilge water that the 22 Cruiser's hull shape (given the rocker it has) would naturally deposit in the cabin (because I think the low point in the "banana" of the hull shape is naturally a bit forward of the cabin door on a Cruiser).

1) A bilge sump that is offset to starboard, and which is slightly in the cockpit and mostly under the galley cabinet (but in a small "dammed" compartment).

2) A bilge sump that's in the center of the boat, athwartships, and just ahead of the cabin door.

3) With a glassed in cockpit sole that slopes to the sump that's at the transom.

3a) If the boat has #1 or #2, then it still/also has a small sump at the transom.

The bilge sump I'm speaking of here is #1. So it is offset to starboard, and therefore slopes athwartships, or "sideways," with the low point just inside the galley cabinet, and the high point outboard of that by 12" or so. It's about a 9º slope. This sump will collect water when the boat is trimmed as it normally would be afloat but stationary. I guess with a camperback not much water would get into the cockpit, but currently I only have a bimini, so some water does get in there. When the boat is parked on the trailer, as it is now, I jack up the front of the trailer enough so that all the water runs aft to the transom drain, and I guess it would do that underway (when accelerating) as well, but otherwise when afloat it seems like some water will flow forward into this sump.

Here is the photo that's probably worth more than 1,000 of my words (from another C-Dory album, maybe rogerbum's? I hope it's okay to use it):



Initially, I was going to put the pump in this sump with the outlet facing outboard, because that would have put the impeller as low as possible in the sump. It fit all nice and tidy-like. But then I saw the "pump must be level" verbiage in the instructions. I wanted to know more because, although I could imagine why it would be bad to have the sensor below the impeller, I could have, for example, turned the pump 180º and still had the impeller reasonably far inboard, with the sensor above the impeller. But... since I didn't know the reasoning behind the instructions (and if it applied to all possible angles of the pump (vs. say just not having the sensor lower than the impeller), I went ahead and cut some small fiberglass wedges to make it level. Yeah, it will leave a bit more water in the sump, but -- without knowing more -- I guess I'm just going to do what they say (in all planes).

I suppose I never "had" to worry about it before, because even with all the complications of a ~6' deep bilge on a sailboat: building a "foot" for the pump and switch to sit on for serviceability, etc., I did at least have a level bilge.

I hope that explains it better. And I probably sounded crabby, but that's because I wish they would just explain more, so I knew if, for example, I could have had the impeller lower than the sensor, or if it really had to be level in "all four" directions. It will be now though, by golly!

Sunbeam

PS: This is not an "automatic" bilge pump - those drive me nuts! It's just a pump with an integral switch, vs. a separate one. Ironically, I returned my "regular" bilge pump with separate switch because I thought I'd be able to get this one mounted in a more efficient way (whereas with the separate switch it had to string out for a ways, side-to-side and thus the slope meant more water sitting in the sump). This one might still end up slightly better in that regard, but not as much as I had hoped, due to the need to be level.

[Sunbeam]

[thataway]

I had not seen the set up that Sunbeam has--so this area under the galley, and perhaps under the aft bulkhead is devoid of core and is double glassed (inner skin and outer skin bonded together, with out the core between, forming the sump). This offset sump appears to comes down to the inboard edge of the lower galley cabinet, and must also be open to the cockpit probably at the lowest end--toward the center of the boat. --so you probably would need to have 2" of water in the bottom of the boat to activate this switch. (I had envisioned that your pump was all of the way outboard near the chine and in the cockpit
.

Of course this brings to mind one question--is the hole in the aft bulkhead sealed with epoxy? The reason I ask is that I saw one boat with some core damage from one of the center holes, and one with some aft bulkhead core damage from the side where water had stood and intruded (the bulkhead was not properly glassed in apparently).

Interesting that Sunbeam used the term "Rocker"--since not too long ago there was commentary that the C Dory boat bottom was flat, meaning that it had no rocker. I was under the impression that there is a slight amount of rocker to the bottom.

I am a little surprised that there is as much as 9 degrees of dead rise at this point. I have never measured it--and I am sure that Sunbeam has! However it is probably 1/3 of the way forward, and 9 degrees would make sense here.

I think I would use a wedge to make it level--or go with the step--as in the later boats, and put the pump in the center.

As I understand the amidships bilge pump concept there is a sump where the water would most likely collect if the boat was sitting in the water.

As you, do, when the boat is on the trailer, I jack up the tongue to the point that any water which gets into the cockpit (I have a full cover, so there is none)--will drain out the back drain, and we don't have to worry about power being on, batteries running down, or bilge pump switches sticking or failing to activate.

I have seen several other ways that the bilge water is handled--one a pump on the outside of the cabin bulkhead just offset to one side. I have also seen wedge shaped bilge strainer pickup, with a hose to a diaphragm pump off to one side with the hose along the aft bulkhead.

When the boat is on a plane, the water tends to go to the aft sump--and Sunbeam is covered by having a pump there. It would be interesting to know with the boat in the water, and a 90 hp Honda, if the water collection by the cabin bulkhead would be deeper with the aft sump pump or the offset under the galley pump, as Sunbeam has. My guess would be it would be a significant amount of water in either case--and probably about equal.

Thanks for the clarification...

[Sunbeam]

Thataway,
If you hadn't seen this particular arrangement before, I can see where it would be confusing - because placing a sump partway "up the side" kind of goes against logic!

[rogerbum]

A few comments -
My previous 22 had the same arrangement. Depending on how your 22 is loaded, at rest, water tends to run forward instead of aft in the cockpit. Hence, a bilge towards the bulkhead. However, the off center nature of this bilge area is just plain stupid. I remember having to sit/stand on the gunnel to tip the boat to the side so that water would get to the bilge when I was at rest. The new version of the bilge on the 22 (with it centered under the door) in much more sensible.

Bob - I believe that Sunbeam meant to refer to deadrise and not rocker.

[thataway]

Roger, I believe that Sunbeam used the term "rocker" correctly. She used a "Banana" analogy, which is correct. Deadrise is the angle from the horizontal athwart ships on one side. Rocker is fore and aft. Depending on how the boat was sitting on a trailer or in the water, any liquid getting into the cabin might run all of the way forward on the floor.

One of the dory type of boats which has the most rocker of any boat is the drift skiff, which is a flat bottom boat. So you can have a single sheet or transverse planking and still have significant rocker. The conversation about flat bottoms I remember was on the post 1987 boats. I even went out and looked at my boat.

I have seen some boats with no core in the sump area--but there can be differences in ear model/year etc. Or there could be "core mat" in this area.
In my 22 there is no core in the forward sump.

In any case, thanks for educating me about how some of the other boats handle the bilge water problem....

[rogerbum]

Bob - Sunbeam can answer for himself. I thought the 8 degree angle he is referring to is the deadrise angle - e.g. the slope starboard down to port in the bilge due to the bilge being off center - and not slope fore to aft. However on re-reading, understand that he was referring to rocker as the explanation for why water pools towards the front of the cockpit.

[Sunbeam]

As Thataway mentions, at various times in this thread I have referred to both deadrise and rocker. Deadrise when I was talking about the 8-9º slope of the forward bilge sump (i.e. athwartships angle). Rocker when I was addressing why water could tend to run forward in the cockpit with the boat afloat (i.e. fore-and-aft curve).

I've been concerned about my boat being starboard-heavy and doing what I could to mitigate that.... heck, maybe with the "side sump" it's not a fault; it's a feature!

Sunbeam

[rogerbum]

[Sunbeam]

I like it No, no, my boat's not out of trim, it's ... jaunty!

Another idea on the "side bilge": just use it as an "excuse" to order that camperback and tonneau cover I already want

Sunbeam

[tpbrady]

"Another idea on the "side bilge": just use it as an "excuse" to order that camperback and tonneau cover I already want"

Sunbeam, a much better solution but seriously more expensive than a bilge pump.

Tom