Weeping Leak between stearn tube and GRP ?

[crg]

Hi All,

Hears the deal - Yanmar 1GM10, 1" Stainless Steel prop shaft, Mechanical seal, Inner Brass Stearn Tube with outer cutless bearing, "P" bracket with cutless bearing to fixed two blade Prop.

I have put the boat back in after winter ashore and discovered a small ( 1/2 Ltr per day) weeping leak between the Brass Stearn Tube / Shaft Log and the GRP, I think this may have been leaking last season but I put it down to rain water ingress through the wash board, Guess the leak has developed due to vibration from the single cylinder engine through the prop shaft and stearn tube causing some movement / vibration between tube and GRP, Questions are:-

1/ How serious is this? I plan to continue sailing through the season and keep a close eye on the leak before, during and after sailing.
2/ How is the stearn tube fixed in the GRP?
3/ Any one seen or tackled this problem before, if so whats the fix?

Photo attached, regards, Cliff.

 

[Poignard]

This stuff sounds too good to be true [maybe it is!] See here - Ding , but it might do as a temporary repeat temporary means of reducing the inflow. Someone on here wll have used it and can advise.You have nothing to lose by trying it except the cost of a tube and a wasted 1/2 hour.

Next lift out I would investigate the leak and try to find out where it enters the hull on the outside. Excavate that area, wash thoroughly with fresh water, dry thoroughly and make a repair using ordinary epoxy. If you only repair the leak on the inside you are not preventing water soaking into the hull laminate.

 

[Athene V30]

If it really works on wet surfaces that would be worth a try - might get some for the 'emergency' bag

 

[tangofour]

To me that looks pretty serious. The crack is clean and new so has not been developing over an extended time. The gelcoat is chipped off cleanly. It could be the engine or perhaps a knocked/grounded or fouled prop.

If you get caught in an emergency/weather suddenly needing full power from the engine are you also likely to be worried that the stern tube is going to let go as well to add to your troubles.

If you are going to continue to operate go below and mark the endpoints of the cracks with an indelible marker pen so that you can really see if the cracks are propogating.

I'd think twice about adding epoxy to it. It will mask the problem and only have to be removed to do a proper repair.

At the very least I'd get check the engine mounts and alignment of the engine / propshaft and coupling.

 

[adl]

When was the stern gland last changed, or removed and inspected? Apparently every 5 years is the norm from reading an article in one of the mags last year. They infered that if there was a total loss due to failure of the stern gland then insrance would not payout if maintenance wasn't adequate. Only reason I ask is if when the prop shaft was reseated it may have damaged the hull. I would want to get the boat out of the water asap and remove prop and glands to see what the problem is.

Depends how quickly you can bale with a bucket.

 

[Twister_Ken]

Is the leak coming through the GRP, or between the GRP and the stern tube?

If the former, there's a good chance you've got water wicking into the structure, and that needs to be properly sorted, pronto, before some delamination occurs.

 

[smeaks]

Could the leak be through porosity/pinhole in the Stern tube at that point?

 

[crg]

Thanks Guys,

Not in to the temporary underwater epoxy repair, would rather do a permanent repair, not sure if it is a crack in the GRP or just the paint line between the Brass Stearn tube and GRP, will have to have a closer look under the paint, engine mounts look good but will have to split the coupling and check the alignment.
Thanks for the stern gland info but I have a mechanical seal fitted.
The leak seams to be between the GRP and stearn tube, Guess I will have to put her on the hard standing and investigate / repair or replace the stearn tube.

 

[Spyro]

If the stern tube is made of brass could it be it has corroded through. Don't have any experience of this but believe it is possible.