Help reuired with a stern gland (WATER COOLED I THINK??)

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mskelton747

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Hello PBO readers. I have rescued a lovely 1972 Fisher Freward from a yard in Scotland and I am slowly restoring her to useable and then full glory. My first step has been to remove the old tired VOLVO MD2B and replace it with a new BETA 1005 which was all going well until I uncovered a clear plastic tube that runs from the stern gland to the old volvo exhaust. I has asumed that this tube was the gland greasing tube but on discovery of its connection to the exhaust I just do not know how it works. I thought it might be Water from the exhaust being used to cool the stern gland bearing but I am not sure. Has anyone else out there got the same or similar setup and if so can you tell me how it works and if they have replaced the exhaust and engine as I have how and where they took the water feed from.

A local lad said that it was a water cooled gland and I should just pack it full of grease using the tube to force grease into the gland and it would be fine but I am concered about this.

Any help gratefuly received..

Thanks

Murray & Machir
 
I have a water cooled stern gland which is absolutely no problem. It needs a positive water feed and has a T off the feed from raw water pump to engine (before the anti-syphon). After 'injection' into the bearing, water passes down the stern tube and exits at the plain aft bearing. How much water goes down it? No idea but there is clearly water being pumped down.

I cannot see how water from the exhaust can possibly be pushed into the stern gland since it will take the easier exit thorough the larger diameter exhaust. Besides it's hot and its supposed to be cooling water! I would just re-rig the inlet pipe as above. I think you cannot take the option of changing to grease since the water was also used to cool the tube and assist at the plain bearing by the prop. That is unless you have a water intake for the stern bearing which will be visible on the forward of the stern bearing on either side.
 
Thanks for the info, I can not understand why the gland connects to the exhaust either. One idea was it was a vaccum tube drawing water up from the gland and not a water cooler?

There must be someone out there with 1972 ish boat and the same setup e.g. VOLVO MD2B with an exhaust that connects to the stern gland?
 
I have a 1962 book on motor boat engines that says

'Other stern tubes are supplied with water from the main coolant circulating pump in order to provide the necessary lubrication, this type of shaft log cooling being found particularly on high speed craft' - not that TG is high speed. Anything but, but of course it makes sense since the water cooling would save the otherwise frequent tightening of the greaser at high speeds.

My experience is that water cooling isn't that common. You could try posting on the classic boat forum.
 
I have had two boats with a tube to the stern gland. One was a conventional gland, filled with packing material, with grease keeping it lubricated, and keeping the water out. The tube on that one was to a remote greaser, mounted somewhere accessible, to which you gave a turn now and then to top up the grease.
The other was a flexible seal supplied by Hayard,with a rubber gaiter, jubilee clipped to the shaft, which compressed two faces together to form the seal. This had a water feed `teed of off the syphon breaker. This again is lubrication not cooling, and has the benifit of cleaning out mud from the cutless bearing if the boat is ´kept in a mud berth, as mine was.
The tee was about 5mm and the main pipe was about 20mm, so most of the water still goes into the exhaust.
Which of these systems seems to resemble yours?
 
Could it be that the water from the stern gland is forced through the bearings and up the tube into the exhaust system where it is then used to cool the exhaust ?
 
The later, the tude seems to T-off the top of the exhaust on a water tight compression fitting but the water entering bearing must be hot so you may be correct its a lubricant and not a coolant?? I wonder if needs presure to force though the bearing or if it just trickles through..
 
It may possibly be a purge pipe that lets air escape, so allowing the sterntube to fill with water via the cutless bearing. The tube would need to be secured vertically so that it extended above the waterline, and when the boat is afloat a visible waterline in the tube shows that the sterntube is full. Suggest you closely inspect the tube/local boat structure for any signs of fixings. If the end of the tube looks as if a nipple has been fitted, it's probably a water injection type.
 
claudio, it could be but its highup and the gland is not a pump. I was hoping that another Fisher owner would read this thread and tell me exactly, the proble, is if I get it wrong what happens to the bearing and 5.6 tonnes that a lot of water to be forced in and lot of boat to be without power..
 
Intersting tugboat but rises from water tight nipple strait up and onto the top of the exhaust baffel where its connected with same compression fitting you would use on a fule line so its water / air tight until it enters the box. I fitting a new plastic exhaust box so I may cut it open to see what is happening.
 
Can you check which direction the water is flowing in the tube ?
You say that the tube is fixed to the upper part of the exhaust. I assume that this is above the waterline. This could act as a venturii and form a vacuum drawing the water up the tube. Where does the 5.6 tonnes come into it ?
 
Yes, I though that might be what happens e.g. sea water is drawn into the tube and gland drawn up the pipe and out the exhaust. Its a good theory but how to test it as she is on the dry and do not want to put her in the water till I am sure.

The other issue is that the exhaust and engine are both dead and are being replaced so how do we create the vacuum with the new engine..? A problems, I can see a replacement on the cards..
 
Is it possible to start the engine up ?
It only need to run for a minute or so.
Disconnect the tube from the stern gland, place the end of the tube in a small jar containing water and some food colouring.
Start the engine, leave in neutral.
If the liquid gets drawn up the tube you will confirm.
You will probably need a hosepipe or bucket to supply cooling water to the engine
 
You will find some information on the Vetus website about a water cooled stern gland.

If I am reading it correctly they have one linked to the pipe after the heat exchanger as well - ie on the pipe to the vacuum break.

Can't see the water being reversed though. Exhaust area will be relatively high pressure, and venturi will tend to draw water out through the cutless as you have a flow of water over it.
 
Murray
I don't want to seem to simplistic here but what you are describing seems to be a bit off an odd system but one that should work in theory.

I think that your tube connection to the exhaust provides a vacuum and draws water up through the gland all the time the engine is running - at low revs small amount of water but at higher revs it should draw more water.

The problem with your system is that when underway you have the engine trying to draw water up the tube and the movement of the boat through the water is trying to draw water down the tube.

My mate has a new fishing boat that has a water cooled gland but his is a modern system that has a separate sea cock mounted at a angle that simply blows water down the tube when under way. You might consider changing over to that system - as long as there's water running through the tube when the shaft is turning you should have no problems - it also means that you can shut the supply off when the boat is on it's mooring - much safer.

Peter.
 
You see this arrangement quite often on Dutch boats, as Vetus stern glands are popular. The stern gland is lubricated by a small tube teeing off at the exhaust, or by a separate seacock. On some boats, a small valve is added in this line to prevent the water from the gland syphoning back. It depends on the general layout. A friend had left his recently purchased boat unused for a month in winter, unaware of the purpose of the valve. Result was an engine full of seawater.
 
Thalassa, that is very interesting so it was HOT water that was pumped down the tube to the stern gland. The reason I ask is that is the most simple solution to recreate as the new BETA has a rubber hose that injects the used raw sea water into the exhuast and all well above the water level. Its a lubricant and not a coolant that makes sense.. Ta do you have any idea the model number of sucg glands / stern tubes?
 
Pye_End, It does, I have scoured my manual and saw no reference can you send me a scan of the page, that would be great. Thanks Murray
 
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