Leak where prop shaft goes through hull!

[dleroc]

I have a leak, about 1.5 litres every 24 hours, into the bilge where the prop shaft goes through the hull. It is very difficult to pin point exactly whether the leak is around the shaft cover or, god forbid, the hull itself. It is very difficult to reach by hand and I have tried to clean the area as much as possible with a view of trying to apply some sort of sealant.

By the way it is nowhere near the stuffing box.

Apart from taking it out of the water or to an area where it can be viewed when the tide is out, does anyone have any experience of similar problems and how they gave been solved? The boat is a Halcyon 23.
Thanks in anticipation!

 

[Tranona]

It could be around the stern tube which may well be bonded into the GRP and the bond has failed. Or if the stern tube is a bronze one bolted through the stern post the sealant might have failed. Only way to find out is close inspection of the area where the stern tube goes into the hull.

 

[Rivers & creeks]

We also had a leak, turned out to be a cracked stern tube

 

[vyv_cox]

Stern tubes can corrode badly, good photo of one on my website.

 

[dleroc]

Thanks all for your assistance so far. Vyv exactly what material is the stern tube made of? So far my cleaning has revealed it to be yellow in colour. I need to do more cleaning around the area but it is very difficult to get any cloth down there. I want o establish whether it is coming from where the stern tuble goes into the hull or whether it is dripping from the undersie of the bit ifstern tube that is visible. Short of getting it out of the water I was thinking of mixing up some resin/ hardener and painting it around the area where the tube enters the hull. Any thoughts?
I am attaching a photo of this area taking a few months ago before I applied new antifouling and beforeI put it in the water. Correct photo now uploaded I hope!

 

[Tranona]

The stern tube will be either a GRP tube bonded into the hull or a bronze tube which may be either bonded into the hull or bolted in with flanges either end. Your photo shows the inboard end of the engine so is no help in determining what sort of stern tube you have or where water might be coming in. You need to access the back of the gearbox and shaft. The stuffing box is attached to the stern tube and that will give you a clue as to the type of tube.

 

[dleroc]

Thanks Tranona. I have now got the photo from inside. I have cleaned it a bit more since then the top tube is the greasing tube.

 

[Burnham Bob]

I had a halcyon 23 and the stern tube was bronze and screwed on to the hull at the back. I sold the boat and the next owner got a leak which he tried to stop by rotating the tube (which has a thread at each end) to tighten up the end by the stuffing box. That was exactly wrong and when he called me I told him to screw the tube clockwise (facing the back end of the boat) to tighten the tube against the screw fitting glassed onto the hull. Leak cured. If yours is the same as mine was then the leak is easily fixed by tightening the tube against the boss glassed onto the hull. You might find that tightening that way will cure the leak at the back but you might need to tighten the stuffing box.

It does (and did on my boat) seem like a terrifying potential disaster. It's not - just a symptom of the way the stern tube is attached. Let us know how you get on but a pair of self grips around the tube should stop the leak.

 

[dleroc]

Thanks Burnham. Sounds good. I'll let you know!

 

[Burnham Bob]

by the way, if the stuffing box is bolted in position through a wooden cross piece (as mine was) you might need to free it, rotate the tube and then unscrew the stuffing box a half turn or so to get it back into position. then it might need tightening as the packing will have lost some of the compression. If your stern tube is the same as mine then its a very minor glitch. However, I only found out how it was fitted when I needed to renew the bearing which was just white metal stuck in the end. As for access, I found that lifting the cockpit floor was a ten minute job (second time I did it!). Take the screws out and break the seal the previous owner has used to make it water proof and when you put it back stick lots of sealant in it. If you take the floor up (and if you are having access problemns you probably haven't) you'll see everything and get at it easily.

 

[dleroc]

No problem in getting the cockpit floor up as you can see. Originally I thought it was the stuffing box that was leaking but not so. I did avtually turn the stuffing box up a quarter of a turn. Here is a photo of the shaft and s box.

 

[Burnham Bob]

mmmmmm my stuffing box was different but suggest you try turning the stern tube anyway to see if that stops the leak

 

[Burnham Bob]

and its all coming back to me - access to the inside of the transom is through the back locker - although the tank may get in the way

 

[dleroc]

Thanks Bob.