Accessing deep bilge pump behind engine?

Someone somehow affixed a Johnson Ultima Bilge 1000 deep in the narrow aft bilge.

Of course, the pump has failed in two ways: (1) the automatic mode does not work (either always on or always off) and when it is on “manual” the flow is low. I have tried to clear the pump by shooting a strong stream of water around it but this has not worked. In any case, the large amount of muck that has accumulated likely would continue to create problems. I have no idea how someone would have been able to screw the pump to the bottom of the bilge since it seems in accessible unless I hold a small but nimble child upside down by the legs! Obtaining parental consent might be a problem Other threads suggest a pump affixed to a platform on a long stick so that it can be relatively easily raised. The only solution that I envision is to leave the old pump there and to install a new one. A second problem is finding a way to remove the muck that likely contributed to the problem. Any advice or solutions would be appreciated.

Paul: Hej!

  1. Have you tried pulling on the wiring lift your Johnson Ultima out from your deep bilge?

Johnson (aka SPX Flow) recommends that their Ultima model is installed by (i) first removing the strainer (depress two tabs); (ii) second affix the strainer to a 0.75" block of marine plywood; (iii) third glue the block of plywood to the bottom of the bilge; and (iv) finally clip the pump into place on the strainer.

I’ve attached a graphic of an Ultima on its recommended mounting block. And another showing the strainer (see the screw holes in it?) separated from the pump unit (and the impeller guard also removed)

I’d guess that jolly few owners of a BCC would follow such directions, if only because it guarantees you have a minimum of 0.75" of water sitting stagnant in you bilge. Further I would guess that an owner of a BCC might use a thinner mounting block of plywood and instead of gluing the block to the bottom of the deep bilge, just lower it in place (using the wiring to lower gently) and with the aim of using the wiring to withdraw the Ultima for maintenance and so on.

  1. The Johnson spec of a mounting block 0.75 inches thick might be needed for the automatic system of the Ultima. Apparently the way to test an Ultima is to place two fingers (of a live person) over the sensor (more or less diametrically opposite the outlet of the pump). And Johnson/SPX recommends that no part of the boat is within 25.4 mm/1 inch of the sensor side of the Ultima.

  2. If the installer just lowered your Ultima into the deep bilge, I would guess that the unit might move fore and aft. And perhaps jam itself into place at a narrow in the bilge? You might use a boathook or other stick of a convenient length to check if your Ultima is fixed in place, whether it can slide fore-aft, and to free it from a narrows so it is able to be withdrawn by pulling on its wiring.

  3. Zygote has its electrical pump in the deep bilge mounted on a bracket which is then mounted on a withdrawable timber rod. The withdrawable rod idea is not uncommon. I’ve seen other vessels with withdrawable rods in everything from timber to stainless steel tube. One significant advantage with a withdrawable rod is that you can choose to install two or more electric bilge pumps - for redundancy and also just to cope with the horror that electric bilge pumps are really poor at dewatering a boat in extreme conditions. Stacking bilge pumps, one above the other, means that you have redundancy that come into play in extreme conditions: if the lower pump has clogged, the upper pump might save the day; or if if one pump is not up to the task of dewatering, then the second might save the hull.

I’ve attached an image of a non-BCC boat with the owner’s withdrawable rod showing two brackets with strainer covers already in place (only the lower pump unit mounted)

  1. As for cleaning the deep bilge, we have in the past withdrawn the electric bilge pump, made a mop (fencing wire bent around cotton rag and then twisted on itself to make a long handle), added a wee drop of environmentally friendly detergent, added freshwater, worked the mop, and pumped out into a pail using a diaphragm pump that swallows most everything. Best done in a work pen on the hard when the pail contents can be disposed of appropriately in the boatyard sump.

med venlig hilsen

Hi Paul,

I recently cleaned out the bilges and replaced both the electric and manual bilge pumps on #bcc-mischief. I removed the aft tank to facilitate access to the aft bilge. I was then able to use a hose and deck brush to scrub it all out and use a shop vac to remove the accumulated debris and the multitude of ancient “gifts to the bilge”. I’ve always used “pine-sol” for bilge cleaning - but if you have a lot of oily sludge, you may need something more robust like “oil eater” (which I used to clean the engine space when I repowered Calypso). We cleaned, inspected, and leak tested the aft tank while we were at it. the electric bilge pump was already mounted on a G10 stick and foot - which made it relative easy to remove and replace. The stick is mounted under the shaft coupling - so not the most accessible thing - but very reachable.

On #bcc-calypso the electric bilge bump is mounted into the deep bilge at the forward end of the engine. It too is on a long “stick” - aluminum bar stock in this case. Calypso has a different arrangement of engine pan and aft tank which makes the bilge directly beneath the engine accessible from the main cabin when the engine cover is removed.


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Thanks so much to Bil (who always has patiently answered my questions and pleas) and to Jeremy as well. The pump does not move along the bottom of the bilge as far as I can see and attempting to lift the hose to it did not budge it). However, it does occur to me that I can detach some of the hose from above and try again, as well as poke around with a stick. And your ideas for “mucking about” in the bilge with various items to clean it are also appreciated. I’m sure that my hypothetical upside-down child worker is also grateful.


  1. Big thanks to Jeremy for his patience and assistance to me. I think the Forum uses Javascript or another scripting language, making my usual browser incapable of performing (and not showing the cyan rectangle with ‘Reply’).

  2. On the ‘automatic’ function of electric bilge pumps: I’ve met several schools of thought. (a) those who are surprised that any boat would not rely on an automatic electric bilge pump; and (b) those who think that (i) an automatic pump is crazy because it is guaranteed to pump out water with a sheen of oil or spilled fuel, thus breaching any boater’s responsibility to be kind to the environment; and (ii) that an automatic pump is crazy because it does not necessarily tell you that you’ve got a problem (i.e. better to know that the boat is making just a shot-glassful of briny a day or as much as an Oktoberfest Bierkrug).

  3. I’m not certain that the sophisticated Johnson Ultima is the right beast for the deep bilge of a BCC. But let’s focus on the simple things:

(a) the automatic function depends on correct wiring. Black (think of the English word ‘swarthy’ = DE schwarz = SE svart) to negative; and two wires brown (EN brown = DE braun = Svenska brun) and brown and white (= DE weiss = SE vit) to positive.

I’ve attached the Johnson wiring diagram.

(b) the Johnson spec for a 3/4" (0.75 inch) mounting board and for the sensor end of the bilge pump to be 1" or 25 mm away from everything are all about the sensor. Put the sensor end of the Ultima close to something (a skin bag holding blood and plasma with some muscle and bone; or even some dense GRP) and the pump in Auto mode will not shut off. I suppose the same is true if you don’t want to use a 0.75" mounting board and use instead something thinner!

I’ve attached the Johnson text warning: keep 25 mm/1 inch of clearance between the sensors and the sensor end of pump or else the pump (even in Auto mode) will run kontinuerligt (depending on the capacity of your battery bank, of course!).

one inch

Hi Paul,

It is remarkable how deep the aft bilge is on a BCC and I have a thought. Someone went to a lot of effort to get your pump placed. Why not clip the leads and keep it in place and use it as a bilge strainer for a diaphragm pump mounted higher? The Johnson pump is centrifugal so water should flow smoothly around the impeller, just a thought. Those little submersibles have a short lifespan.

I’m working on a bilge pump system too right now for Vixen. She has a wonderful old dual action manual diaphragm pump mounted where a crewman can sit on the settee and pump like crazy. It will shift a lot of water but the weak point is the bilge strainer. The bilge is so deep I’ve resorted to mounting lead weights on the strainer and letting it drop to the lowest point in the bilge. If it gets clogged with something, I can bring it up to clear and the pump can be easily taken apart without tools and cleaned. But this is just the manual pump, I’d like to have two electric pumps for day to day use.

A long time ago I was invited to board the Pardey’s boat and they did something I thought was very clever. There is a big bronze pipe on the after deck for the bilge water. The way I understand it is you can see if water is flowing and it was well above the waterline… I’d like to incorporate something like this as sort of a tattle tale.

I used to race old deep keeled wooden boats around the buoys in high winds and waves. These boats were lapstrake so would leak a lot as the hull worked in these conditions. So, on the downwind leg, the middle crewman would pass out beer and then pump out the water, a lot of water. We had great trust in manual diaphragm pumps. I’m going to school like you on electric bilge pumps.


“The pump does not move along the bottom of the bilge as far as I can see and attempting to lift the hose to it did not budge”

Drat. So perhaps someone really did glue the mounting block to the deep bilge!

I’ll tell a story, a real one, from the marina we call home. Three characters: Chris a young bloke who’d bought a steel hull and was cutting out rusty plates and welding in new. Glenn, a middle-aged bloke most famous for being the brother of Tony who plays no part in this story. And Unnamed, owner of a big MV. and to whom I never talked (and so never learned his name). Story goes (and we witnessed part of it) that Chris was walking back to Echo row (which as you will understand is right close to Foxtrot row, where Z has her home and which explains why we knew Chris well). Chris fell in with Glenn, who was walking back to Alpha row and they chatted. After passing Golf row but before they reached Foxtrot, Glenn heard something - a noise, a cry. He encouraged Chris to join him in investigating. Just as well they did - what Glenn had heard was a weak cry for help from Unnamed, who was stuck head first in his deep bilge without the strength and capacity to get himself out and had been in that position, emulating Benito M, for at least 20 minutes. Young Chris pulled Unnamed out. They called the paramedics. Unnamed spent a couple three days in a hospital bed, with the understanding shared by all that he would not have survived another 20 minutes of inversion.

We added a new rule to Z’s book: don’t work in the deep bilge without a buddy right there.

I checked the website. A link to a multilingual manual for the Ultima: But no 3D model.

If you found a retailer carrying a Ultima, you could measure the diameter between the two tabs that lock the pump body onto the strainer. And estimate the force necessary to depress the two tabs.

Then if you’re not prepared to copy Unnamed (with a buddy standing by), I’d suggest seeing if you could make a tool that could lock onto and depress both of those tabs simultaneously.

It might be that it’s not possible - that the dimensions of the deep bilge are such that neither a human hand nor a tool could get in position to press those two tabs.

In which case the only things I can suggest are 1. Paul’s initial idea to just ignore that pump; or 2. to blow or pump big mobs of air or even warm sudsy water under pressure down the outlet hose to clear muck away from the impeller of the Ultima (perhaps using a second bilge pump) and then to use a diaphragm pump, mop, etc to skim and otherwise remove as much of the muck as possible and 3. Rich of Vixen’s idea of putting another pump in series with the Ultima (or at least the Ultima’s strainer).

You have tried the simple fix of just reversing the polarity of the DC leads to the Ultima, yes?

Most electric bilge pumps are simple DC motors, so reversing the polarity should reverse the direction of the impeller rotation. Whether that is effective in cleaning out the strainer compartment is a different matter.

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I returned to the boat to sail for a couple of days and took another look. Sure enough, there was a vertical piece of wood screwed to the back of the deep bilge behind the engine, with a 1/8" horizontal platform to which the pump was mounted. Had to disconnect a vertical piece of hose from a connector (which probably reduces the flow) and cut the wiring to get it out. Surprisingly, there was little debris on the strainer or around the impeller. I’ll go ahead and test it at home. There was a check valve that reduces the hose diameter where it meets the pump and also likely reduces the flow, but it seems to me that a check valve is necessary given the amount of water that would drain back into the bilge. The pump is rated at 1000 gph and fits a 3/4" hose which looks like it is fitted to an adapter at the thru-hull which may take something closer to an inch diameter hose. Seems a little underpowered for what might be needed. I see the photo of a Rule 1500 with manual float switch. What do others use?

What ever I replace it with, I’m thinking that I’ll add a couple of feet of wiring so that the next time it is lifted out the wiring can remain intact.