Strange water intake system

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35mm

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Not new to boats, but only had this boat for a few months. I don't understand the water intake system for the engine, and don't particularly trust it. To explain it, I'll start at the engine water pump and work backwards. Hose from pump to cock/strainer. Larger hose out of cock/strainer to domed fitting located mid-ships just ahead of stern tube. External inlet/hull fitting on port side of keel quite a way ahead of domed fitting! Some how there's a discrepancy between where the domed fitting disappears into the concrete ballast and the position it comes out through the hull. I don't trust it too much because the water comes through a hose, into the boat and is hosed a few feet before it gets to the cock. Presumably it is also hosed through the concrete ballast. So that's is a potential failing point.
 
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35mm said:
Not new to boats, but only had this boat for a few months. I don't understand the water intake system for the engine, and don't particularly trust it. To explain it, I'll start at the engine water pump and work backwards. Hose from pump to cock/strainer. Larger hose out of cock/strainer to domed fitting located mid-ships just ahead of stern tube. External inlet/hull fitting on port side of keel quite a way ahead of domed fitting! Some how there's a discrepancy between where the domed fitting disappears into the concrete ballast and the position it comes out through the hull. I don't trust it too much because the water comes through a hose, into the boat and is hosed a few feet before it gets to the cock. Presumably it is also hosed through the concrete ballast. So that's is a potential failing point.
Click to expand...

Photo`s ????

is it a keel cooling pipe
 
There's just one hole on the underside for water intake, but it's no where near the domed fitting on the inside. There's no simple, straight through skin fitting/cock. The hole on the outside is on the port side and about a meter ahead of the domed fitting on the inside which is midships. Oh, and the cock is some where entirely different. I can't quite fathom it!
 
Here's some pics I found. Note the intake on the underside on port side, and the dome fitting in the bilge, midships. And we haven't even got to the cock yet - that's just in front of the engine.
 
That dome headed unit is directly under the prop shaft right on the centre line and about 20 inches behind the stern gland.

Not sure how far behind the stern gland the external sea cock opening is but it is certainly off the centre line and therefore cannot be the same.

You need to measure how far back from the stern gland each one is before anything else otherwise it is pure speculation.
 
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To give you some perspective, that intake on the underside is pretty much level with the front of the engine. But it's the only intake there is down there. So it has to be connected to the dome fitting, via a pipe that must be buried in the concrete ballast. It's a very odd layout and what concerns me is that there is potential for a leak to occur any where between the intake on the underside, and the dome fitting, and on until the sea cock which is just by the flywheel.

In fact it's just dawning on me that the external intake is pretty much directly below where the cock is inside. However, I have removed the cap on the top of the cock, and the filter and tried to poke about with a welding rod. It didn't seem to go through the hull. It's only connected to the dome thing via a hose. It sure as hell doesn't make any sense to me. If it does go through the hull straight to the intake, then what is the hose to the dome thing all about?
 
I suggest pouring some water through the system to make "sartin sure" what's connected to what.

Here's my theory. The strainer is connected direct to the skin fitting. The dome is a strum box. The valve changes over between the two to let the engine intake be used as a bilge pump.

Pete
 
prv said:
I suggest pouring some water through the system to make "sartin sure" what's connected to what.

Here's my theory. The strainer is connected direct to the skin fitting. The dome is a strum box. The valve changes over between the two to let the engine intake be used as a bilge pump.

Pete
Click to expand...

This is also what I think....The concrete has been poured as an afterthought and maybe buried a three way cock under the flywheel which would as others say allow the engine pump to draw from the bilges or the sea. The domed unit is the strum box in the bilges.

My only concern would be whether the concrete was only poured in as ballast. I would check the hull on the outside and under the concrete to see there are no deformations or signs of damage to the hull.

Old sailors poured cement boxes in ships to stop leakage!!!!:D:D
 
Strum box. Interesting. The concrete was added during the build as ballast when it was built in @ '73. The concrete is only in the centre "V" of the bilge and runs the length of the boat. The sea cock is located above the concrete level on GRP.

There is a manual bilge pump - old brass type, so probably original, but no strum box on that. I can't really see any reason why it would need a separate bilge drainer that could drain through the intake or potentially send bilge crud through the engine block.

I'll do some more experimenting and see what's what.
 
You say the seacock is located "on GRP". Does that mean it is attached to the hull? If so, from what you have described the seacock is directly connected to the intake and there is a second port to that strum box so that you can draw water from the outside or the bilge. Used to be a common set up.

Disconnect the hose from the pump, pour water down it and see where it comes out. With the handle in one position it will come out of the hole in the bottom, in the other out of the strum box. There may also be a third position where it goes nowhere because the outlet to the pump is sealed.

Photo of the seacock and piping would help.
 
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