Leak in a stern tube

I'm not sure if it's called a stern tube or shaft log but it's the tube that my shaft runs through the Cutlass bearing from the stuffing box. Any ideas on how to get the old Stern tube out to replace it with a new one

You might be better off seeing if you can slide in a new slightly small tube to line the old one.

I did what capt bill said on my Nordic Tug. Put a smaller tube inside the existing tube and then a smaller cutlass bearing.

Interesting. If a smaller tube will fit how would I seal it. Injecting some epoxy maybe? By the way is it a stern tube or a shaft log?

S-Dude!!! Long time no see!

No direct experience but years ago RickB posted a fix he did I believe involving 5200. He fished a cable through it and hooked a "bullet"(long disc) just under the size of the hole. Once ready to pull the bullet through he dumped the whole tube of 5200 in the hole and pulled the bullet through effectively sealing it from the inside.

I may be messing that up a bit but you can look up the post and check. Good to have ya back.

Deltaville Boatyard did mine. I think they glassed it in. 7-8 years ago. Can't remember.

Really would have to see your setup...but the standard TT type deep keel on a single engine....some have pressed them out, some cut from the inside of the boat...some from the sides of the keel...anything to relieve some of the pressure/friction and get an grip on it to speak.


Repair is done with another tube or coating the inside with 5200 as RickB reportedly suggested...others have used thickened epoxy and multiple coats.

Many don't worry unless the leak is excessive.

Is this a common issue? Is the stern tube structural in anyway? Where do you notice the leak?

Are you talking about the short rubber hose between the stuffing box and the cutlass bearing? Or do you have a fiberglass tube I between the cutlass and stuffing box?

It's the tube that my shaft is in runs from the stuffing box to the Cutlass bearing

I like the idea about the 5200 on the pole in the billet through the tube. Means I've got a haul the boat again

Got any pics? Where is the leak? My nagging thought is: Why did this leak start? Is the shaft rubbing the tube, abrading the inside of the tube? Is the alignment off that the engine has settled? Is there an intermediate bearing that is failing? Does the shaft have a whip in it, allowing it to rub? The rubber hose sections do wear out, and get spongy. If it is leaking on the aft side, it could be 'spraying aft, appearing to be leak in the tube.
Fixing the leak is one thing, figuring out why the leak started is probably more important.


If you have an issue, installing a smaller diameter inner sleeve will buy you time. But if this is a rubbing issue, it will rub through quicker. How long is the tube you are talking about? Is it fiberglass? Or is it a couple inches of rubber?

which type do you have?

I would love to add a few photographs but I don't know how to upload them on this thing. I'm on the boat what does url mean. Doing this from my iPhone 5

My stuffing box rests up against a bulkhead. Water is weeping out from a crack on the fiberglass of the bulkhead. I just recently installed a new 3208 n.a. The alignment seemed fine every thing bolted right up.

skipperdude said:

I would love to add a few photographs but I don't know how to upload them on this thing. I'm on the boat what does url mean. Doing this from my iPhone 5

Click to expand...

I use the iPhone 5 to access this site too. Do yourself a favor and download the Trawler Forum App. Adding pictures is stupid easy after that, especially if you take them with your iPhone.

How do I find the trawlerforum app

skipperdude said:

How do I find the trawlerforum app

Click to expand...

On your iPhone 5, look for the blue "App Store" application. Then do a search on "Trawler Boating Forums". Open and install it. You will need your Apple ID and password to do the install.

Skipperdude, on the pics i put up, on the one with number 1, 2 or 3 on it, where is your leak coming from? 1, 2 or 3? If it's from 1, you need a haul out. The previously mentioned caulking 'quicky fix' won't help a tube that is cracked from the back at the hull joint. (at least not for my money) Well, 5200 may buy you some time, but if it's the tube to hull fiberglass joint that is failing then you have a larger job to do to refasten the tube into the hull. Its one thing if the tube it self is worn or cracked.

If it is the tube to hull joint, if you have access to the entire way around the tube you could slap on some more fiberglass and beef the connection up from inside the boat. But getting it to stop leaking to actually put more fiberglass on is the trick. It would involve a dive outside, and sealing the shaft cutlass bearing and any water weep holes with beeswax (toilet bowl sealing ring works well,) and letting the wax get pushed in by seawater pressure. Then using a vacuum to suck up the water, and then acetone to dry up the remaining dampness. Acetone is very explosive. Air out the bilge the entire time with blowers.

You have to understand, the leak is small now. Something is failing. If it completely cracks, and overwhelms the bilge pump (and batteries) the boat will sink. That's about a 2" hole in the hull.

If you didn't align the engine reinstall correctly, it could have whacked the stern tube enough to crack it. Is there a boat repair yard near you? The 'why' it cracked is worrysome to me. If you don't figure out the Why it will likely happen again. And you know it will happen in the winter in AK......

It's easier to use than the desktop version


Sent from my iPhone using Trawler Forum

Coppy. It's leaking behind Number one. This boat is set up kind of different I don't have traditional motor mounts my engine is mounted by brackets that hang over the stringers and hard mount directly to that. when checking things out I found that one of the motor mounts the bolt had come loose and the engine was no longer mounted on the aft starboard side. The leak seems to have slowed down a bit. This was originally a commercial fishing boat and has three watertight bulkheads. The water is leaking from a crack in the fiberglass of the bulkhead at the back of the engine compartment about 6 inches above where the stuffing box is mounted to the stern tube. In effect the water is filling the bulkhead and then leaking out.

SD: If you can get to the crack, you could use Splash-Zone Epoxy. It will bond to wet areas and can be applied under water. I've seen it used and it is all that it is advertised for.

http://www.pettitpaint.com/fileshare/product_pds/Splash-Zone.pdf

I had a stern tube leak.
Didn't discover it untill I observed my aft bulkhead had moved fwd over an inch. That was because the steel in my concrete ballast in the Lazerette corroded enough to expand enough to cause the bulkhead to be pushed fwd. Big problem to say the least.
It was concluded that the FG stern tube failed (probably due to freezing and water) and allowed water into the boat and that seawater penetrated the ballast ect ect.
Removing the ballast w two different sizes of jackhammers was a job from hell to be sure. I only did about 20% of it but that was bad enough.
How the FG stern tube was removed I don't remember. It was done by the yard. Don't think it was that difficult .. just work that boatyard guys know how to do. Putting the new stern tube in involved building a shelf like pocket just ahead of where the stern tube exited the boat (keel) and that shelf was filled w resin called "chalkfast" (as I recall). They used this special resin as it's shrinkage is minimal. That was critical to the installation. Several boat bucks but all went well and has been for about ten years. I replaced the concrete ballast w lead and may be a bit over ballasted now but I also removed a heavy item from the stern.

Skipperdude I suspect that your stern tube is installed much the same as mine except for the ballast (lucky you). So at your haulout a good FG layup guy would be very desirable. I can supply you w knowledge about the people in Bellingham WA that make FG stern tubes should you be in need.

This is strictly a DIY job the nearest boatyards at least 70 nautical miles from my location either going to Valdez or around to Seward which puts it in about 200 miles one way to get to and from the boat and my home and I'm not even sure there's anyone there that can do the job. It's also the middle of fishing season silvers are running I've got numerous people coming up for boat rides this summer all of August so I think I'm going to rig an extra bilge pump just to be safe. The boat won't fit on the trailer so I can't call it to Anchorage it won't even fit through the 2 1/2 mile railroad tunnel that it takes to get out of Whittier. Seward.is 114 nautical miles i76 Cordova where most of the fishing fleet is. Is 110 so it's a fix it myself or no boat. Not complaining it's a matter of fact I'd rather do it myself.

Larry m. I can't even see the crack in the tube anyway. all I can see is where it leaks out. my boat has three watertight compartments The engine room the fish hold and the fuel lazaret. the Stern tube runs under the fish hold. I'm going to have to remove a large section of a bulkhead just to get to fiberglass that I can glass on to.

Thanks many boats. I'm better at fiberglass work than anybody I found when I replace the engine I had to cut away a 4 x 8' hole in the side of the boat just to get the motor out I rebuilt the whole thing myself that all the glasswork. So fiberglass work I know it's just being able to get to it so I can do the glasswork. Wouldn't be so bad but the silvers are in big time this year. I picked up a 20 pound hog yesterday.

First you have to get it to stop flowing water. Can you dive on it and plug it with beeswax from the outside? Toilet bowl seals (wax rings) are wonderful tools. Get it dried up.

Then either use thickened resin. Or the mentioned splash zone epoxy. I've used both with excellent results.

You don't need to fill the bilge, Just a round dollop around the shaft to and overlapping the hull material.

You're going to have to figure out how to re fasten the engine though. It will just break again if you don't get to the cause of the problem.

I am either missing exactly what the setup is and just what fix is in order....if it is a long tube all the way through the keel like mine...about 9 feet of it...and it is leaking into hollows in the keel....then just what "fix" is wanted?????


My possible leaks and many others with leaky tubes and single engines have resorted to the fixes I have posted earlier....definitely a haulout/major repair.

The pics below are not of my boat but some other kind TFer that emailed the process in pics to me when I had questions. Sorry to the pic taker...but thanks again!!!!

Just fixing water coming through a crack without knowing the origin (like what I am thinking but could be totally wrong)...would not satisfy me.

I didn't catch it until a couple posts ago, He seems to want to do a quicky repair, in the water, finish the charter season, then repair it.

SD. I think, using some of the techniques mentioned would buy you the time to actually get to a haul out. If you are thinking of doing this as a permanent fix.... Are your customers lives worth it? Is yours? If this tube completely separates you are looking at a 2" hole in the boat, a couple feet under water. That's a LOT of head pressure to blast water in.

Until (and unless) you actually figure out WHY it cracked (likely the engine replacement and mis alignment) it will likely get worse.

Unless it is unreinforced resin...composite usually doesn't catastrophically fail.

It may grow, worsen, etc...but closely monitored should not be a big suprise.

Psneeld. Your pictures look similar to what I have. my Stern tube is full of with water all the time. next to the Cutlass bearing are two small ports that allow water in. They look like small scoops on either side of the keel. The shaft extends out to a strut encasing another cutlass assembly then the propeller. The rudder is supported by the skeg extending out from the bottom of the keel.