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Post by nickwight on Sept 8, 2022 12:27:28 GMT
While investigating (with no success) how salt water was getting into a chamber under the forward berth bed (see previous post), I have discovered that there are a worrying number of areas throughout the boat where if water gathers it will be trapped and there is no pump to extract it.
One area in particular bothers me and that is the well under the D4 engine. As far as I can see, should water enter this area there is no where for it to go until it is deep enough to flow over the transverse beam just forward of the engine, into the area where there is a bilge pump, by which time the lower 25% of the engine would be under water.
Therefore, I am considering fitting a third bilge pump in that engine well area, with any water being pumped forward into the area where there is already a pump. Has anyone else done that?
Also and I've only briefly looked at this, but it appears to me that there are no maintained DC circuits on the boat -- that is, when the battery isolators are turned off, ALL power to the bilge pumps is cut. Surely I have misunderstood this and that's not the case?
Any thoughts or information on this will be most welcome. Nick.
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Post by Charlie-Bravo on Sept 8, 2022 17:18:37 GMT
I have no idea what a NC9 looks like, but, the bilge pump power supply being off when the batteries are isolated does seem a common way to receive a boat, easy enough to wire a circuit to suit your preferences. As is the isolated bilge under an engine.
Having a live pump when all else is off isn’t such a bad idea, but the pumps supplied are for occasional emptying of the bilge of water from maintenance tasks and the odd leaky pipe, not there to save your sinking boat, although they can help a bit in the event, so does a washing up bowl . They do make a noise which can be an early indication of a problem, but you have to be there to hear it and passers by may well ignore it, perhaps a ‘live’ alarm with significant db and on deck flashing lights would be better.
The bilge under the engine is isolated to catch oil and fluids from the engine and so not pumping them into the sea, it also highlight’s an engine system malfunction e.g. a bilge full of pink fluid means a coolant hose is in distress. My SO35 has a forward bilge that is isolated , no idea quite why, but when the cabin sole starts to float it highlights a dodgy fresh tank fitting, all be it a bit late.
Could your unexplained salt water leak be coming from the anchor locker ? (haven’t read the other post yet)
CB
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Post by Charlie-Bravo on Sept 8, 2022 17:33:06 GMT
just had a read of the other post, …….. probably not the anchor locker suggestion, 25 L is rather a lot, could this have accumulated over a long time, or is it a sudden occurrence? if sudden pull the boat. Thruster tunnel sounds a likely culprit, have you had your head down there with someone else driving into waves (a great experience that will be !) CB
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Post by nickwight on Sept 8, 2022 18:35:27 GMT
Hi Charlie-Bravo and thanks for your response.
The reason that this 12v supply arrangement and the absence of a pump in the engine well concerns me, is that on our last but one boat a pump in the engine bay running on a maintained circuit DID save that boat from sinking! I wont go into all the details here, but the pump triggered automatically and kept running long enough and was just able to keep pace with the water flooding in from a failed bellows, for us to get the boat lifted out
I do see your point about the risk of pollution, but the well under the Volvo Penta D4 engine is so large that even if the engine should dump all of it's 12 litres of oil in one go, it would not reach a depth sufficient to trigger the automatic pump. Also, modern pumps have switches that can differentiate between water and other fluids and will only activate for water.
The thruster tunnel might be the culprit, but having now investigated further, I know that the "chamber" under the bed that held the water, actually connects to a bilge under the liner, that runs for almost the whole length of the boat and so the water could have got in from just about anywhere. So I'll need to get out the talcum powder and keep searching!
Kind regards, Nick.
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Post by Charlie-Bravo on Sept 8, 2022 19:52:13 GMT
Most fortunate that the pump continued running and could keep pace with the flood, preventing loss, and I’m sure you understand the point that pumps don’t run forever and that with perhaps a 2” heads outlet failure things might have gone very wrong rather quickly, I suffered a split hull and no pump was going to keep pace!
Still think alarms and flashing lights would be good.
Im not overly fussy on the pollution bit,( perhaps I should be) but seeing what is leaking in an engine bay, including the quantity I value more than the hassle of manually removing it once the cause is rectified, and so choose not to link my engine bay to the main bilge, …..each to their own.
Good luck with the powder trail leak hunting, sometimes kitchen roll sheets work just as well, sooner or later the cause will be found, and I look forward to reading where it is all coming from.
CB
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