How do you pump your bilge

[Danny Jo]

It wasn't until around 200 litres of water entered via a dodgy shaft seal last year that I discovered the inadequacy of my arrangements for pumping the bilges. There is a 40mm pipe leading from box fixed amidships (to the lowest part of the bilge) to a manual pump by the helmsman's seat in the cockpit. This pipe is perhaps around 6 m long and includes a number of joints. The combination of dead space and opportunities for air entry at the joints strikes me as inherently unsound for a pump that works most effectively when it is full of water.

An electrical pump located in the bilge would be more effective, until the electrics fail. What then?

 

[Seanick]

Don't use deep sea seals!

 

[matelot]

I dont. Its dry year in and out. I dont use thee old style stuffing box which has to drip to work but the modern lip seal system which interestingly they use on commercial shipping.

And thats not simply a glib answer - on a modern GRP boat like yours, you really should have a bone dry bilge. The wooden old bangers have an excuse but not us. /forums/images/graemlins/grin.gif

 

[Danny Jo]

[ QUOTE ]
Don't use deep sea seals!

[/ QUOTE ] After the incident in question I installed a Volvo shaft seal. This involved removing and machining a new surface on the shaft and is very effective.

Solving one problem has left me with another potentially serious problem. Like the Deep Sea seal, the Volvo seal relies on water for lubrication. Unlike Deep Sea seal, the Volvo seal has no built-in device to ensure that, after an initial purge, any air trapped behind the seal is vented. Although I was warned that one must "burp" the seal after any episode of drying out, I was not expecting to have to burp it at regular intervals - somehow air is getting trapped behind the seal. Discovering this and another problem which exacerbates it gave me a nasty shock.

It was a fabulous day for sailing, and we were on route from Tobermory to Rhum. We were reefed down a bit, having just refitted the starboard after lower shroud the shackle for which had failed, but were still cracking along at hull speed or better. We became aware of a high-pitched whining sound, a bit like a jet engine some distance away. Eventually I discovered the source - the shaft was rotating at a very high speed, and the shaft seal was too hot to touch. I hate to think what might have happened if it had got any hotter. This, I think, could only happen in the following conditions:

(a) a dry seal - how the air or other gas gets in their beats me;

(b) a self-pitching propeller (i.e. Brunton Autoprop) - a fixed pitch propeller would be limited by the flow of water, which is limited by the hull speed;

(c) a fancy gear-box clutch that I don't understand (i.e. Yanmar YM30)

Now before you jump in and say I should have a shaft brake, or stop the engine in gear, let me explain why these solutions don't work. In the first place, I don't have room for a shaft brake. And I have tried every permutation of stopping the engine in forward or reverse, or stopping it in neutral and switching to forward or reverse - I cannot reliably stop the freewheeling in the gearbox. So every time I stop the engine I now have to go through an elaborate routine: stop in forward gear; lift floor to see if shaft is still rotating; if rotating instruct helm to set throttle to reverse; if this fails, put on a shoe and apply gentle pressure to the shaft coupling; burp the seal.

It's a good job sailing is fun. But don't get me wrong - the Yanmar - Volvo - Brunton combination is in every other way brilliant, and has added to my enjoyment of the sailing.

 

[aluijten]

Quote:
An electrical pump located in the bilge would be more effective, until the electrics fail. What then?

Although true on itself, a well laid out electric bilgepump will help itself in keeping electricity available (keeping the batteries from flooding). One thing that will help this a great deal is to use a pump that is not located in the bilge itself and is self priming. So a hose from the bilge to a point high in a locker where the pump sits and from there overboard.

Pumps that sit in the water most of their life are bound to fail when you need them most. Only if your bilge is perfectly dry most of the time, submersible pumps are an alternative.

Cheers,

Arno

 

[Danny Jo]

[ QUOTE ]
on a modern GRP boat like yours, you really should have a bone dry bilge

[/ QUOTE ] Er, yes. Freestyle is built of cedar strip and epoxy resin, covered with three layers of mahogany and epoxy, covered with glass epoxy, and should be bone dry. But last year I discovered 6 causes of water in the bilges:

1. Failure of the aforesaid Deep Sea Seal, which, to be fair, was around 5 years past its use-by date.

2. Failure of the junction between the starboard freshwater tanks and its filler hose, combined with a 20-hour spell close-hauled on a port tack.

3. Failure to switch port heads to "empty", or to shut seacocks, combined with a stiff breeze on starboard tack.

4. Condensation from fridge.

5. Failure of pressure relief valve on calorifier, causing hot water to escape when engine is running.

6. Failure to secure forehatch before entering the overfalls.

Etc.

 

[Sans Bateau]

Our electric bilgepump, rather than having a banjo on the end, has a length of clear plastic pipe. This pipe will reach anywhere in the cabins/bilges. This is most useful to vacuum up water when taking out/replacing the log paddle wheel. I have also used it to evacuate the cooling water from the engine and calorifier, here though I placed a hose on the skin fitting so the water went into a bucket on pontoon rather than in the water.

 

[acbruce]

My family had an early Nicholson 35 with hydraulic drive. We were supposed to stop the the prop free-wheeling to avoid overheating the hydralic motor when no cooling was supplied. The "shaft brake" was a bracket with a hole through and a small hole drilled in the shaft. One was supposed to place a metal pin through both to stop the shaft turning. Of course you then had to remember to take it out before using the engine.

Of course you inevitably forgot so we substituted a match for the pin and amazingly it worked fine. Then it didn't matter if you forgot!

The point is that a shaft brake can be very slight if one stops the shaft by hand/foot first!

 

[Danny Jo]

[ QUOTE ]
Of course you inevitably forgot so we substituted a match for the pin and amazingly it worked fine. Then it didn't matter if you forgot!

[/ QUOTE ] Thanks. This reminds me that I did work out a solution of sorts, but failed to write it down: a wooden wedge under the bolts of the shaft coupling, light enough to be attached by a very short lanyard to the engine key; then, when you want to start the engine the search for the key (where the hell did I put it? Oh, yes, of course) will lead you to remove the wedge.

 

[matelot]

Interesting that is is cedar strip - how do you find that maintenance wise? Any problems with water into the cedar? I guess a number of people on the forum would be interested in knowing a bit more about it in practise so how about a post on the subject? /forums/images/graemlins/ooo.gif

 

[Danny Jo]

[ QUOTE ]
Interesting that is is cedar strip - how do you find that maintenance wise? Any problems with water into the cedar?

[/ QUOTE ] I forgot the mention the laminated mahogany frames. This construction makes for a very rigid hull, and provided the epoxy coat is kept intact, it is likely to last at least as long as GRP. A big bonus is the built-in insulation - I get virtually no condensation. The only problem comes when folks use the hull as a handy fastening point, driving screws and bolts through it and allowing water in. Whenever I replace or refix a fitting, I drill out a wider hole and epoxy in a "sacrificial" teak plug. After 20 years it still looks good from the inside.

 

[cyczebhes]

Ok, we all have a dreadful moment. This is the potted version . But I did learn a neat trick should I ever be in such a position again. My boat has both manual and electric pumps. My prop shaft became detached from the coupling and the rudder saved it from escaping further. This opened the stern gland and of course a lot of water. I discovered this when I went below.
I was just outside a the marina and managed to get an engineer aboard
Of course the electric bilge pump had failed and the water was by now above the sole boards. Now for the neat trick. He removed the engines raw water intake feed and passed it into the bilge. The engine then pumped out the bilge.

 

[Refueler]

Another trick is to use the bog. Take pipe with rag - anything to pack around to create a seal with pipe rammed into bowl outlet. It works. Not as fast as engine intake, but useable. One guy I knew had a rubber bung from a "Scupper-Gun" ready just for the job.

 

[Lakesailor]

I have a man to do it

 

[matelot]

my very first big boat was a hunter built from a kit by a man who was a shopfitter by trade. I sailed it very happily for a year and then took it out of the water at our club. Wanting to empty the water tank which had an internal filler, I stuck the wandering hose of the bilge pump through the filler hole and started pumping. Nothing happened. Persuaded SWMBO to pumpo whilst I investigated and found a gurgling noise from the tank. Turned out that he had attached the hoses the wrong way round and it was blowing not sucking.

Good job I didnt have the above posters shaft problem.