Where did it all go ?

dunedin

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A minor Irish mystery.

Filled water tank full before leaving Ardglass marina. Headed out to sail south, to discover unexpectedly bad waves (breaking over rocks at edge of entrance). After some deliberation decided to proceed with plan and head south, upwind to Howth, taking fairly major pasting en route.

Arrive at Howth after fast sail. Check water level and down to a under a quarter of a tank - when not been used at all en route due to conditions.

Have we split the tank or a loosened a pipe by the pounding ? Not as far as we can tell, having lifted the floorboards playing hunt the water.

Is it the tank sensor damaged ? No, after some debate tried topping up and after a long fill had climbed back to 3/4 full when stopped filling.

Did we lose the water out the overflow pipe when heeled ? Would need to be very very heeled to do this, and surely would get salt water in the tank which passed the taste test.

Sailed on for 3 days checking regularly and water still there. With normal usage tank slowly reduced slightly to just over half full.

So where did it all go - 75 litres or so ? Any ideas ?
 
If the fresh water left your tank and did not end up inside the boat there are only two options I can think of:

1. Syphoned out.
2. Pumped out.

SYPHONED
Is is possible that with the way you are set up at a certain angle of heel the overflow could discharge and then start to syphon? In the right conditions it would not take all that long to syphon out a load of water.

PUMPED OUT
If conditions were bad, would you have heard the fresh water pump (assuming you have one) operating? What might cause it to kick off? Maybe something daft like a bit of crockery or something which pressed on the switch while you were out on deck dealing with the weather? Seems unlikely, but....

I can't think of any other possibilities. But as I say if it's not in the boat it was either pumped out or syphoned out - unless of course it leaked out from your filler!
 
on my boat there is a stopcock on the outlet pipe. If I forget to use it, on a hard port tack, the water tank is above the sink, so it flows to the tap and simply goes out the drain! This obviously only applies if the tank is off the centreline... but gives a reason not to close the sink drain seacock - but its above the waterline when level.
Rob.
 
Could a tap have been running -- the passage noise would cover up the sound of the pump. Otherwise it went into the bilge. I have a bilge pump monitor (an integral part of the BEP battery meter) which I highly recommend to everyone. I picked up a leak from the generator exhaust hose elbow after a stainless steel worm-drive clip (not allowed to mention the common name here as the manufacturer's lawyers are watching this forum but you probably know it as a [---word removed ---] clip; many of them not made by [---word removed---], of course, are prone to fail). A bilge pump monitor is one of the most important bits of kit you can have on a boat, telling you have many cycles since reset and for how long the pump ran.

If it went into the bilge, then I would be suspicious of a corroded weld on a stainless tank. Or a broken [---word removed---] clip on a pipe. You could block the vents and pump it up a bar or so with the dinghy pump to test it.
 
Thanks for your suggestions. It certainly didn't go into the bilge, which I had at first assumed as we lifted all the boards and checked.
The pump option is not imposible, though pretty sure it wasn't on when we reached calmer waters.
The siphone idea is a new one I had not thought of - but with the outlet well above the waterline suspect was going in and out of the water each wave cycle so would get an air-break every few seconds.
Usefull pointers - gues will now need to monitor and see if it recurs

thanks again
 
[ QUOTE ]
It certainly didn't go into the bilge, which I had at first assumed as we lifted all the boards and checked.

[/ QUOTE ]You don't have an automatic bilge pump?
 
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