2001 Beneteau 361 water seepage at or near prop shaft exit through the hull

[Jerry D]

I’m currently trying to diagnose a water leak associated with the prop shaft exit area. It leaks when the boat is just sitting. This 361 has a Volvo seal that has been greased and does not leak at the forward end.

After closing the small thru hull valve that supplies water to the shaft, it seems the leak quit. I snugged the two clamps and it’s possible the leak has been cured. I had to leave the boat shortly after this.

My big fear is having a leak from the glassed in tube or the base of the hose nipple. When putting her up for the winter, I did not push antifreeze into that hose, but the thru hull was left open. Hopefully it drained and ice didn’t cause damage.

Next week the rear engine mounts will be replaced along with the Volvo seal (I’m guessing just the inside seal, not the entire black boot needs periodic replacement). The front engine mounts were replaced before spring 2023 launch, primarily to replace the broken engine bracket ($500 part…improved with reinforced gussets) on the starboard side. Ultimately we replaced both front brackets and rubber mounts but have not checked the alignment.

After replacing the rear mounts, I’m going to suggest the yard haul her and remove the cutless bearing to verify the shaft is centered in the tube. Then install a new cutless, launch her, and re-check the alignment while floating. Also need to remember to burp the seal.…

Hopefully these steps make sense but I’m hoping for suggestions if y’all have any. My main concern is about the water seeping in and having a potentially hard to diagnose leak. Any guesses on this?
Thanks,
jerry

 

[sailaboutvic]

Are you sure it’s not leaving from the seal on the shaft ?
are you sure it’s not coming from some where else and setting in the lowest point . ?

 

[Jerry D]

Yes, I’m fairly confident it is not from the seal, at least not the forward end that secures around the shaft. It may be coming from the aft end of the black boot that is secured by the two Allen head screws. But, I may have overlooked checking those two screws for tightness….

When I return this week I’m bringing a scope that will allow me to peak around corners so I hope to find it before the mechanics work on it the following week. Thanks for your thoughts.

 

[Plum]

I’m currently trying to diagnose a water leak associated with the prop shaft exit area. It leaks when the boat is just sitting. This 361 has a Volvo seal that has been greased and does not leak at the forward end.

After closing the small thru hull valve that supplies water to the shaft, it seems the leak quit. I snugged the two clamps and it’s possible the leak has been cured. I had to leave the boat shortly after this.

My big fear is having a leak from the glassed in tube or the base of the hose nipple. When putting her up for the winter, I did not push antifreeze into that hose, but the thru hull was left open. Hopefully it drained and ice didn’t cause damage.

Next week the rear engine mounts will be replaced along with the Volvo seal (I’m guessing just the inside seal, not the entire black boot needs periodic replacement). The front engine mounts were replaced before spring 2023 launch, primarily to replace the broken engine bracket ($500 part…improved with reinforced gussets) on the starboard side. Ultimately we replaced both front brackets and rubber mounts but have not checked the alignment.

After replacing the rear mounts, I’m going to suggest the yard haul her and remove the cutless bearing to verify the shaft is centered in the tube. Then install a new cutless, launch her, and re-check the alignment while floating. Also need to remember to burp the seal.…

Hopefully these steps make sense but I’m hoping for suggestions if y’all have any. My main concern is about the water seeping in and having a potentially hard to diagnose leak. Any guesses on this?
Thanks,
jerry

Different Beneteau but I have the same arrangement with the boat out of the water and that seacock open all water will drain out through the seackock and through the shaft tube out through the cutless bearing so there should be no water in there to freeze.

When in the water, that seacock has no function if the hose is entirely below water level. Even if the seacock is closed any leak between it and the propshaft-tube will not be isolated as the water will continue to come in through the cutless bearing. I know this because I had a leak and was shocked that the leak did not stop when i shut the seacock!

www.solocoastalsailing.co.uk

 

[sailaboutvic]

Yes, I’m fairly confident it is not from the seal, at least not the forward end that secures around the shaft. It may be coming from the aft end of the black boot that is secured by the two Allen head screws. But, I may have overlooked checking those two screws for tightness….

When I return this week I’m bringing a scope that will allow me to peak around corners so I hope to find it before the mechanics work on it the following week. Thanks for your thoughts.

I would mop it up dry the lay some toilet paper in different spots you soon see where it my be coming from .

 

[Plum]

I’m guessing just the inside seal, not the entire black boot needs periodic replacement)

The internal lip seals and the black boot are all one moulding, you cant replace just the seals.

www.solocoastalsailing.co.uk

 

[Jerry D]

Different Beneteau but I have the same arrangement with the boat out of the water and that seacock open all water will drain out through the seackock and through the shaft tube out through the cutless bearing so there should be no water in there to freeze.

When in the water, that seacock has no function if the hose is entirely below water level. Even if the seacock is closed any leak between it and the propshaft-tube will not be isolated as the water will continue to come in through the cutless bearing. I know this because I had a leak and was shocked that the leak did not stop when i shut the seacock!

www.solocoastalsailing.co.uk

Ok, thanks for eliminating freeze damage.

i believe both ends of the rubber hose from the small seacock are below the water level. What function does it serve?

Replacing the black boot is what I should plan on. I don’t know when the Volvo seal was replaced, if ever. Is this the factory installed seal or was something else original? I’m left wondering what purpose the small water line has.

Seems like the area below the “nipple” where the small rubber hose connects stays glossy/wet. I’ll plan to replace the hose when it is hauled. Will water shoot out if it is removed (seacock closed) While the boat is floating?

 

[Jerry D]

Different Beneteau but I have the same arrangement with the boat out of the water and that seacock open all water will drain out through the seackock and through the shaft tube out through the cutless bearing so there should be no water in there to freeze.

When in the water, that seacock has no function if the hose is entirely below water level. Even if the seacock is closed any leak between it and the propshaft-tube will not be isolated as the water will continue to come in through the cutless bearing. I know this because I had a leak and was shocked that the leak did not stop when i shut the seacock!

www.solocoastalsailing.co.uk

I think you answered a couple of my questions with this earlier response. TY

 

[Concerto]

I would mop it up dry the lay some toilet paper in different spots you soon see where it my be coming from .

It is better to use either blue elephant bog roll, or personally I would use talcum powder as it washes away where any water runs.

 

[ithet]

When I first got our B331 (similar shaft arrangement) she had a slight leak caused by a hairline crack below the stern tube where it comes out through the skeg. The skeg is actually hollow and open to the boat, and water ran through and sat in the area of the shaft seal. I had extra glassing and sealing done.

 

[Plum]

Ok, thanks for eliminating freeze damage.

i believe both ends of the rubber hose from the small seacock are below the water level. What function does it serve?

Replacing the black boot is what I should plan on. I don’t know when the Volvo seal was replaced, if ever. Is this the factory installed seal or was something else original? I’m left wondering what purpose the small water line has.

Seems like the area below the “nipple” where the small rubber hose connects stays glossy/wet. I’ll plan to replace the hose when it is hauled. Will water shoot out if it is removed (seacock closed) While the boat is floating?

Best not to remove that hose while in the water, yes, even if the seacock is closed water will come in.. That seacock is attached to a skin fitting that scoops water due to the forward motion of the boat so a little water flows into the prop tube and out of the cutless bearing to keep the bearing cool. The hose needs to be as short as possible with minimal height in order to avoid an airlock in it. Also, every time the boat is launched/refloated the VP black shaft seal must be burped (to release any air trapped behind the lip seals in the nose). You can do this by applying finger pressure on one side of the nose to distort the lip seals and allow air out until water starts to dribble out, then release. The water keeps everything cool, air will not. VP say the shaft seal should be replaced after 5 years but others in this forum have reported much longer lives. My one was still sealing perfectly after 15 years and 800 engine hours when I replaced it with another genuine VP one just for pease of mind.

Www.solocoastalsailing.co.uk

 

[Tranona]

You may want to consider replacing the seal with a similar one made by Radice (who also make the original Volvo one) that has a vent and a greasing point. The air vent goes above the waterline and removes the need for the water feed.

 

[mrangry]

You may want to consider replacing the seal with a similar one made by Radice (who also make the original Volvo one) that has a vent and a greasing point. The air vent goes above the waterline and removes the need for the water feed.

Thats interesting as I have just ordered one of the Radice seals to replace the old Volvo one. When asked about fitting the supplier said I should connect my water feed hose onto the Radice seal and blank off the nipple on my Beneteau stern tube.

 

[Tranona]

Thats interesting as I have just ordered one of the Radice seals to replace the old Volvo one. When asked about fitting the supplier said I should connect my water feed hose onto the Radice seal and blank off the nipple on my Beneteau stern tube.

You can do that. The seal can be either water fed or vented. Normally the water feed is needed only for higher powered boats and fed from the engine. However Beneteau use that scoop arrangement on all their boats even though it is not really necessary in terms of cooling water. It does remove the need for burping the standard Volvo seal, but many boats rely just on the water coming up the short tube through the cutless bearing. With a higher speed boat there is a risk of water being pulled out of the tube leading to overheating the seal. should not happen with a sailing boat. I have just fitted a Radice to my boat which has a stern tube that is well over 1m long and just vented rather than water fed.

As it is there on your boat no reason not to use your water feed, but suspect it would work just as well vented to air.

 

[Beneteau381]

Yes, I’m fairly confident it is not from the seal, at least not the forward end that secures around the shaft. It may be coming from the aft end of the black boot that is secured by the two Allen head screws. But, I may have overlooked checking those two screws for tightness….

When I return this week I’m bringing a scope that will allow me to peak around corners so I hope to find it before the mechanics work on it the following week. Thanks for your thoughts.

on my 381 the brass tube that is glassed in toth figlass tube just aft of the clamp ofthe rubber seal de zincified and turned rotten. It then leaked. I sourced another bit of tube and araldited it in. Been ok for the last ten years