Oceanis 37: stern tube/stuffing box vent or feed pipe?

[Rob Heath]

On our Oceanis 37 there is a small bronze nipple on the stern tube, just aft of the stern gland seal, with a hose attached. The hose is connected to the top of a Vetus Air vent (AIRVENT_V_H_installation_instruction.pdf (vetus.com) ), I'm note sure whether it a "V" or an "H" model. As far as I know this is how the boat was delivered from the factory.
The manual shows the nipple connected via a pipe a through hull, which I think could just lead a bubble of air in the pipe.
Does anyone know the purpose of this connection to the stern tube? Does it let air out, or feed water in please?

 

[sail sfbay]

The Volvo stuffing box manual (attached) says "ensure that sea water is circulating through the inside of the seal to ensure full lubrication that will secure the [sealing] function......Some installations may require extra water supply to offer proper [sealing] function. Your Volvo Penta dealer can also confirm. This thread on your stern tube might be informative (1) Check your stern tube water nipple | Sailboat Owners Forums

 

[Rob Heath]

Thanks @sail sfbay

I have an update on this....I have given some incorrect information....

On re-inspection the hose from the top of the air vent goes to the bilge and there is a second hose (of exactly the same type!) that goes from the back of the heat exchanger to the stern tube nipple. So it is indeed a water feed for the stern tube.

Mystery solved!

 

[BigEasy]

Thanks @sail sfbay

I have an update on this..there is a second hose (of exactly the same type!) that goes from the back of the heat exchanger to the stern tube nipple. So it is indeed a water feed for the stern tube

Beneteau must have changed their design, originally, they installed a dedicated thru Hull fitting & ball Valve assembly, specifically for the shaft seal cooling / lubricating water. The thru Hull fitting was adjacent to the shaft; the stern tube nipple hose was secured to the thru Hull valve & nipple with double hose clamps.

 

[Rob Heath]

Beneteau must have changed their design, originally, they installed a dedicated thru Hull fitting & ball Valve assembly, specifically for the shaft seal cooling / lubricating water. The thru Hull fitting was adjacent to the shaft; the stern tube nipple hose was secured to the thru Hull valve & nipple with double hose clamps.

Yes, this is what is shown in the manual. I attached the page to my original post. I suspect this arrangement could just lead to a bubble of air in the pipe, which may be why they changed it.