[Public-List] My Leaking Stern Tube Current Status

[George Dinwiddie]

Daniel,

On 9/26/18 5:11 PM, Daniel Swords via Public-List wrote:
> Current status, I hired a diver to check out the stern tube leak. As
> most know, there are two hex-headed machine screws that attach the
> cutlass bearing housing to the deadwood keel of the boat. They are
> just tapped into the fiberglass. Some may say a bad design but it has
> lasted 45 years so I can’t complain.  The top screw needed about 1
> and 1/4 turns to snug down ( but I warned him not too tightly because
> I didn’t want to strip it out) but the bottom screw was totally loose
> and would not tighten.
> So it looks like the easy fix will be to remove the screws, reamout
> the holes and fill them with epoxy (Marine Tex?) then drill and retap
> the holes and reinstall the screws with 3M 4200 caulking.
I suspect you don't need to completely fill the holes. Just make sure to 
get epoxy all around. I would soak with liquid epoxy to get a good bond 
and then, before it sets up, put the filled epoxy (MareneTex would be 
good) on top with a popcicle stick. That will make drilling and 
retapping easier.

I use 3M 5200 on these bolts and the cutless bearing flange. It's easy 
enough to pull later, heating the bolt/flange with a propane torch to 
soften the caulk if you have to. I don't generally have to do that in 
this situation, as the bolts are large enough to take some torque and 
accessible enough to provide it.

> Still some concern, is this just a symptom of age or is there another
> problem like shaft misalignment or excessive engine (Yanmar)
> vibration. The haul out yard I hope to use is a Yanmar dealer so I
> will rely somewhat on their assessment. Still afloat but still
> waiting for a haul out.
Have you been noticing vibration? I can imagine that if the cutless 
bearing housing was floating a bit, it could quickly wear the bolt holes.

I'm glad you found the problem. It seems relatively straightforward to 
repair, if a bit of a PITA.

  - George

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