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Guest plesbit

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Right, another one to resolve here.

During my dismantling of the thermostat housing on our engine yesterday I decided to trace some of the pipes on the engine. The RAW water intake on this boat is connected to the leg, which it often is on these types of boat. On Silver Dream that had been blocked off and the raw water was drawn through the hull in copper pipes. On Grenick, it is drawn through the leg, like usual, using only rubber piping. But there was no sea cock at all. I traced it several times to be sure. A large rubber pipe, coming off the port side of the leg assembly and running along side of the engine and up into the sea water pump mounted on the forward end of the engine. There could be no doubt.

I don't understand how you can have an intake like that and have no means of blanking it off. I open the strainer and sure enough the water did not come flooding in, but that is probably above the waterline. But since the top of the drive is underwater and the intake comes off the bell housing of the drive what if the pipe should fail there? Also, what about changing the raw water impeller since that means opening up the raw water system? Any comments / suggestions?

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Hi Simon

In my limited experience with these drives, on our Princess the water take off from the drive unit was via an stainless elbow pipe from the bell housing, this was high enough to take it higher than water level. If they are rubber hoses below water line can you use a pipe clamp to carry out routine servicing such as impellers etc? With all drives you have to put your trust in the security of rubber pipe and bellow connections, as on the river side you have the main drive bellows and water intake hoses also. Failure of any will result in water entering the boat. It is esential these are replace at the correct intervals.


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Thanks Colin. I think the intake might JUST be able above the waterline, but it's very touch and go on that, and the pipe then ducks down and runs along quite low on the engine. I'd feel a lot happier if there was a way of properly shutting it off. From the setup it doesn't look possible that you could actually fit a seacock to the intake, at least where it comes off the bell housing, which might explain why there isn't one. Silver Dream also didn't have them on either drive both as she had been redesigned to draw water through the hull it didn't matter. The thru-hull intakes were copper not rubber and did have seacocks.

If wonder if anyone knows whether this (i.e. no seacocks) is a standard setup on stern drive boats. Can't remember what the drive type is, unfortunately.

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Perfectly normal Simon, some have water pumps mounted on the engine and draw through a skin fitting and the usual seacock, some have the pump mounted in the drive and pick the water up through the leg. Obviously the engine mounted pumps are easier to service and replace an impeller in an emergency but provided you replace the leg impeller at the specified interval you should have no cause for worry.

Whilst on the subject of seacocks (and any other critical hoses), make sure each one is double clipped with quality wide section hose clips such as JCS which are Lloyds approved. Try to steer clear of Jubilee clips except for non critical stuff like potable water systems etc. Certainly don’t even allow non branded B & Q type garbage near your boat.

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Thanks David. The water pick up is through the drive but the pump is mounted on the front end of the engine. Changing the impeller would be a fairly easy task but there is definitely no way to shut off the incoming water. Before reaching the pump it rises up to a strainer which is well above the waterline. Since you can open the strainer and remove the filter without water ingress presumably this also provides the same protection when opening the seawater pump to change the impeller.

The bit that bothers me is the >1m or so of rubber pipe from the drive up to strainer. If this should fail there is no way to shut the system off. (It actually looks pretty new so I doubt failure is imminent but I'd like to be prepared just in case).

Oops, must dash....

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Boats have been running around like that for years so I really wouldn’t worry. However if it eases your mind then tie a piece of dowel of the correct diameter to the hose and then you can cut and plug if needs be using the sharp knife that should always be readily available aboard.

P.S. hope the incontinence improves. :naughty:

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Got ya. That's basically what I was getting at - is this natural / normal / desirable. If the answer to that is yes then I am happy enough. Not having had the benefit of seeing many (any) other engines like this I had nothing to compare it to. My mind is at rest now.

PS - The incontinence will probably get worse rather than better if the meeting I just attended is anything to go by. I must change the wall designated for banging my head against as the plaster is starting to crack and the cleaner keeps complaining about the blood stains. :roll:

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