Stern gland feed take off

[seaangler23]

Fitting a new stern gland, similar to the Volvo / radice type but it has a water feed for an internal rubber bearing, the engine is an indirectly cooled yanmar 3ym20.
Now I have 2 options for taking a feed, there’s a drain on the hose on the raw water pump outlet I could tap into for a cold water or the hose from the heat exchanger to the exhaust elbow. I know then temp after the heat exchanger should not be high enough to bother the bearing so I’m thinking there rather than bleeding off pressure before the exchanger or does it make no odds?

 

[snowbird30ds]

Mine go from oil cooler drain on volvo tmd41a.

 

[Tranona]

Do you have an antisyphon valve? The take off must be downstream from that. The water feed is not really necessary for a low powered, low speed application. Normally it is only necessary to use that feed as an air vent to well above the waterline. That is what I have with a Beta 30

 

[seaangler23]

Mine go from oil cooler drain on

Mine go from oil cooler drain on volvo tmd41a.

that’s before the heat exchanger isn’t it on the tmd?

 

[seaangler23]

Do you have an antisyphon valve? The take off must be downstream from that. The water feed is not really necessary for a low powered, low speed application. Normally it is only necessary to use that feed as an air vent to well above the waterline. That is what I have with a Beta 30

No anti syphon valve, this stern gland has a cutlass style bearing moulded in behind the seals which requires the water feed and not just a vent tube, I’ve not seen them before but it will be interesting to see how it fairs,

 

[Tranona]

No anti syphon valve, this stern gland has a cutlass style bearing moulded in behind the seals which requires the water feed and not just a vent tube, I’ve not seen them before but it will be interesting to see how it fairs,

Do you have a link to the seal you have? The Volvo type also has a water lubricated fluted bearing similar to a cutless and water comes up the stern tube. The vent is to prevent airlocks when launching. With the non vented type you have to "burp" to expel the sir, but only once as when the stern tube is full the water is there to lubricate. The seal is made by the lip seals moulded into the forward end and they require periodic lubrication.

 

[seaangler23]

Volvo Type Stern Seal - 25mm Shaft & 42mm Stern Tube With Water FeedDefault Title
Instructions state for it to have a water feed and not just to vent the tube

 

[Daverw]

My understanding is that the water feed is not required for slower sailing vessels and only for faster motor vessels

 

[Tranona]

Volvo Type Stern Seal - 25mm Shaft & 42mm Stern Tube With Water FeedDefault Title
Instructions state for it to have a water feed and not just to vent the tube

Yes, that is made I think by Orbitrade in Turkey and is identical to Volvo/Radice in construction. It does not need a water feed in your sort of application although that is an option. If you do want a waterfeed then you will need to incorporate an antisyphon valve if the feed is from the raw water injection into the exhaust otherwise you run the risk of syphoning back into the engine through the exhaust elbow. On the Beta to avoid that there is a take off on the raw water side of the heat exchanger to avoid this problem. However a positive water feed is only required for higher powered/speed vessels. The photo shows my installation with a Radice on a 30mm shaft, Beta 30 and simple vent. Although the tube is very long (around 1m) never any problem with water even though it has a cutless bearing at both ends of the tube.

 

[snowbird30ds]

Yes, the raw water goes from pump to gearbox to oil cooler to heat exchanger to exhaust elbow, on tamd I think inter cooler is between pump and gearbox.

 

[seaangler23]

Yes, that is made I think by Orbitrade in Turkey and is identical to Volvo/Radice in construction. It does not need a water feed in your sort of application although that is an option. If you do want a waterfeed then you will need to incorporate an antisyphon valve if the feed is from the raw water injection into the exhaust otherwise you run the risk of syphoning back into the engine through the exhaust elbow. On the Beta to avoid that there is a take off on the raw water side of the heat exchanger to avoid this problem. However a positive water feed is only required for higher powered/speed vessels. The photo shows my installation with a Radice on a 30mm shaft, Beta 30 and simple vent. Although the tube is very long (around 1m) never any problem with water even though it has a cutless bearing at both ends of the tube.

Thanks, that saves the hassle, il run a vent tube and keep an eye on it