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Bilge pumps


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My boat was broken into a few weeks ago. The villan(s) left the washboards out and the hatch open letting an unknown amount of rain inside. Apart from nicking some tools, they probably did me a favour.

 

I thought I should check how much water had found its way into the bilge. Despite the carpet in the cabin being soaked, the bilge was all but dry. However I did discover something of concern that will be my winter project to fix. Unfortunately the bilge pump drains.... wait for it.... back into the bilge. There is about 2m of hose neatly coiled up beside the pump, so I think this may be a previous owner's unfinished project.

 

I'll need to get it sorted, but first I have a couple of questions you guys might be able to help with. The boat is a Spencer 28.

 

The first question is where is the best location for the outlet? I can get from the bilge, up inside the galley joinery and out through the hull relatively easily with a short run of hose. However the skin fitting could be be under water with a good heel on (about 150mm below the toe rail is the highest I can get) and there's not really any place to fit an anti siphon loop that won't look unsightly. From what I'm reading, using a backflow preventer valve might be risky.

 

The next easiest option is to go out through the transom via the quarterberth. I think I can position the outlet so siphoning won't be a problem, but this is going to require a much longer run of hose, with a number of turns along the way. I estimate about 5m all up. How is that going to affect the efficiency of the pump?

 

A third option might be to drain into the cockpit via one of the cockpit lockers. It would be a much shorter run, but I don't like the idea of possibly oily bilge water being discharged onto the cockpit sole if we are also dealing with some sort of flooding emergency.

 

Next question is the pump. The present one looks quite old. I can't see a brand on it, but it's a low profile automatic type. I haven't tested it yet, but I'm thinking it might be time for a new one. The electrical connections are a mess, so it will need to be rewired properly. So any thoughts on what are the good brands, what size, etc. Is it better to have a separate float switch? Some advice suggests using two pumps so as there is a backup if one fails, and extra capacity if there is major flooding? Thoughts on this?

 

Of course I can look at my nice dry bilge an think the pump will never be needed. Like the last one that probably hasn't moved a drop of water in the last 20 years. But it's about being prepared for that day when something unexpected goes wrong isn't it?

 

Thanks for any thoughts and advice.

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....make your own float switch !..

In-water rocker type float switches are as above....they fail often.

Nearly as bad is that they collect debri under the hinge when running and then simply dont turn off.

This means that they can either burn out or in a light battery/solar panel combo, kill the battery.

Which in turn means that the boat stops pumping and starts filling. This is more common on a swing mooring due to the boats movement than one might think.

In essence you have a piece of pvc pipe with a few holes drilled in it standing upright in the bilge. I use 32 mm but you could go smaller if you wanted to)

On top you make a simple "seesaw" in plastic . A sealed reed switch and magnet attached.

On the end of the "seesaw" you have a stainless tig wire with a float on the end that sits down in the bilge inside the pipe.

Parts are cheaper than a commercial one, the electronics and any connections are out of the water, the float cant get fouled, you make it so it suits your space (and can therefore remove it without doing "bilge yoga".)

If you swap the tig rod for light SS threaded rod, you can make it so that the float and hysteresis is fully adjustable.

If your pump has a high current load, then install a relay up with your auto/off/manual switch. (You should have one anyway in this case)

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Thanks for all the advice.  It's really helpful.

 

KM, I'm going for the transom.  I lifted the cabin sole and cleared all the junk under the quarter-berths yesterday and have worked out a route for a 28mm hose that won't need me to destroy anything structural or cut holes where I can't get.  I'll be going under the quarter-berth panels rather than just under the deck where I was first thinking. The run will be just a tad over 5m,  I need to get between the ribs and the hull in a couple of places, which is why 28mm hose will be the max.  The old pump has a 19mm outlet, but it's stuffed, so I may as well go bigger while I'm at it.  As you say, not much extra cost.

 

One pump I've looked at is the TMC 2000GPH.  It will just fit in the space by the look of the advertised measurements.  Does anyone have any experience with them?  There's also a Vetus that might fit, or a more expensive Johnson that I think is going to be too fat.  The old pump was possibly a smaller Rule, but the label has gone.

 

Idlerboat, I saw the DIY float switch instructions on another thread.  Maybe a good idea.  I'll look into that a bit further.  I'll also check out the ball bearing switches KM mentioned, and maybe the new iSwitches too!.

 

After yesterday's effort my bilges are spotless!  A previous owner took the time to paint everything nicely, so cleaning is a breeze.  It was surprising what had found it's way down there though, and some of it was worryingly organic!

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Guys, my website is now down until I come back to NZ. The best bilge controller by far is the smartswitch one. See www.smartswitch.co.nz for the site, or http://smartswitch.co.nz/downloads/specs/BSW%201000.pdf for the float and controller for a small boat. If you want one, tell Neil (the owner/designer) that Matt told you to call him direct, cause I'm not here!

If you use one of these, you'll likely never need to replace it. Its for pumps to 44 amps.

IMO the TMC pumps and the Rules are both Crap. The Johnson is much better...

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I've found simple ball baring float switches to be very reliable. They are the one where when the water rises the float lifts making the ball baring roll to the other end creating a circuit. I can't think of a simpler cleaner more reliable way of making one. 

 

They are a terrific design, but suffer from partial contact and arcing on the contacts.  This is because pumps have a large draw in start up and the contacts rely on the weight of the ball bearing. Which varies a lot from verticle to fully horizontal.  This design was originally filled with liquid mercury and was a flawless float switch.  An electrical relay based system these days is the most reliable. Because of the problem of partial contact with mechanical systems.  Unless current draw is minimal.

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Wow! Some nice products from Smartswitch IT, and good to see them Kiwi made. Thanks for the info on the pumps too. One of the deciding factors will be the diameter of the pump as it needs to fit in a tight little gap between the hog board and bottom stringer. Some more precise measurements are in order.

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Yep the Ball bearing type ones eventually wear out the contacts. That is why they came up with the Mercury idea. But the problem with any float type switch is that it has a high level for turn on and some bilges can end up with a lot of weight in water before they start to pump. IT's unit uses a time feature so that the pump runs longer than the float position would normally turn off, thus allowing for more water to be removed and a lower switch on level can be set. I also like the idea of having a suction type pump in the lowest level bilge as that will suck completely down to the bottom, won't block with debris and happily run dry if left running.

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.......Strange as it may seem....

a small amount of "back flush"...that is water returning back down the suction hose after the pump turns off is a very good idea.

It clears the accidental debri  (such as stuff like human hair, paper towel) that is in most normal boats, that has been drawn up against the strummer box grill.) Yes it is still in the bilge sump, but it stops the ever increasing cover of the strummer box. (Or in most commercial ready mades the clip on plastic grill around the impeller) 

You do of course still have to do bilge yoga from time to time to clean it out : )

 

A lot of vessels are beautifully kept with rigorous routines and ideal equipment. Some of their owners are bald and dont have pets on board. These boats have no gaps between their cabin soul floors, and nothing coming off their engine pipes lagging or indeed any loose insulation. 

Their shower sump boxes never overflow.  No grease comes from their packing glands.

....and heaven forbid that a small tool would ever find its way unknown into a bilge...

 

... my input is not meant for those people.

 

 

My suggestion about bilge switches was not at all about me being a crazy DIY nut...(although I do think sensible boat owners should do more).....but because there are genuinely gaps in what is available, at even quite high prices. Reliability in some marine equipment areas is not as good as it could be.

Float switches is one of those. 

I have replaced many...of all types...including the ball type. 

I am happy to debate if you doubt me, but I suggest you start by looking at the seals where the wires go into these units.

If you never have any water in your bilge then you may be lucky....but if there is enough water to activate the switch then it means that the wires are constantly getting washed...

that is getting moved. The seals cop water, oil, detergent...and more.

and fail...a tiny amount of moisture in the ball type renders them unreliable.

 

So why would you have all that underwater when you dont have too ?

 

.......and ...if you have a traditional timber boat...keep your bilges wet.

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OK ..now that I am grumpy...

lets talk about bilges...

after all it is more fundamental than the bilge pump.

What sort of bilge do you have on your boat ?

How many ?

If more than one, does one drain into the other ?

If a long bilge does it have a sump, or baffles ?

If its a tiny little bit of plastic....how long do you think thats going to hold water before it travels through the rest of the boat....or are you relying just on the magic bilge switch and electric pump....

to turn on...off...on...off..on...while moving a bats pee..

 

How long does it take you to access it ?

Is it deep enough or too deep ?

Can you reach the bottom...without inspector gadget ?...

Can you reach the bottom in a light gale without throwing up ?

Do you have a light in there ?

 

And for those who say "My boat is dry"...

 

Whatever.....

 

my boat has NO through hulls....NO seacocks... NO raw water.and a dripless stern seal...

 

But I have still had rain driving in from aft hard enough.....

I have still had the cockpit filled (center cockpit too) with a single wave...

....and knocked over a bucket of whatever... 

All enough to test the bilge....

 

.....if you take home "STorm Raiders Pride"... back to the yacht club at the end of the day...suck her out with a wet n dry vac...and apply wax....

 

you have probably got bored and not read this anyway.

 

 

 

 

 

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Funny very different bilges indeed,

Strangely enough I am now on my 5th keelboat and the last 4 have had only manual pumps, mainly because of dripless seals on the engine shaft (or no shaft) and very shallow bilges.  The first boat had a lovely deep bilge and all the water ran to a sump where the pump was, so an electric pump made sense. With the more modern shallow or non existent bilge a sponge is usually all that is required.

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Unless the boat floods for some reason. A scavenger pump is good for boats with little bilge area and no sump. Which is a pita offshore, as dewatering is difficult. Everything gets wet...

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One of those "important things to have in your toolbox" things for me is a Wet and dry vaccy. OK so it doesn't actually fit in the tool box and many wouldn't have room on the boat even. But having access to one is great. I regularly vacuum out the bilge areas and I am always shocked at what I suck up. Also it's good to suck up the main bilge directly below the engine. I have one of those Perkins engines that come with the self anti-corrosion system, namely, it leaks oil all over the show, but at least it stops corrosion. Early Perkins and Fords are terrible for it and the old saying was, "How do you know it's time for an oil change?  When it stops leaking" . Anyway, sucking the crap out of there ensures I don't pump oil over the side.

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