[Public-list] stern tube Leak Repaired.

[Jim & Carole]

Don,
 
Thank you for your  letter. It was very generous of you to take the time 
to go into such detail.
After pulling the boat I spent the day cutting loose and pulling the 
stern tube. I worked on cleaning the thiakol until my chest gave out 
from lying atop the engine. The marina spent the next day  scrapping and 
grinding the area clean and rebedding the tube. I'm happy to say that 
all worked out well and my bilge is bone dry.
Jim #565

Don Campbell wrote:

>Hi Jim;
>    Water on the shelf that you describe is probably at a lower point in
>the boat  relative to its entry point, and it is often difficult to see
>where it has come from. Nonetheless, making the correct diagnosis is key
>to affecting the correct repair.
>    The best I can suggest is to try to get your dry hand, or dry dark
>paper into the area to see if it is coming from the rudder post or the
>stern tube. start high and work down until the paper shows darker and
>wet.  Dyes carefully placed work too, but the key is to not apply them
>in any place you do not want them,  which is not easy back there. If you
>have done anything with the cutlass bearing holder, or tried to tighten
>the stern tube packing without holding the stern tube very solidly, it
>is quite probable that you have broken the thiakol seal. I have found
>that there is considerable variation with hull thickness at this point
>in the molds, and thinner tends to leak more easily than thicker as you
>might suspect. Almost any movement of the stern tube ( a couple of
>thousandths of an inch) will allow for a leak in the thiokol.
>    The shelf you describe as cracked is entirely internal to the boat
>and should not be leaking per se, unless there has been serious damage
>to the hull from a solid grounding, or that perhaps the bolts/screws on
>the rudder shoe have failed internally. I do not think there is a void
>within the construction here to allow for easy moisture migration.
>    Since you say you are lifting the boat out of the water, I would be
>using a moisture meter on this area of the hull, and checking the screws
>on the rudder shoe carefully, expecting no problems, but checking
>nonetheless. It may be a good time to check the bottom of the rudder
>post where it fits into the shoe as well
>    If you are going to rebed the stern tube, it is an awkward chore
>that takes time because of the difficulty of getting hands and tools in
>to the back end interior of the boat. I believe you will have to take
>off the prop shaft and cutlass bearing holder to get the thiokol out as
>it is a really sticky mess.
>    IT IS NECESSARY TO HAVE A ROUGH BUT VERY CLEAN SURFACE FOR 5200 TO
>BOND TO!!!
>    I found that a cup style wire brush on a drill was as efficient as
>anything to help clean up the surface of most of the grey stuff. For the
>corners, I used whatever I could from scrapers to flat wire brushes,
>(both hand and drill mounted),   to wire toothbrush sized equipment.
>Then I used several acetone washes, but ventilation needs to be good for
>that, especially in summer.  If you can get that through a pressure
>washer soap venturi, that may be the way to get in easily. You might
>want to experiment with several solvents to see if you can find
>something that will work to dissolve thiokol well, ie various alcohols,
>varsol, acetone, degreasers or other VOCs but all require very careful
>fume control. SAFETY FIRST. I did mine in weather that was less than 50
>degrees F and so the thiokol was solid and the fumes less than they will
>be in summer. I also had the motor out at the time for one reason or
>another,  so access was not as difficult as it might have been with the
>motor in place. It is still an awkward place to get to,  or rather back
>out from,  once one is prone in the motor area!
>    As you might imagine, I have taken things on my boat apart and put
>them back together several times, so have the system fairly well defined
>now. If you want the full method, let me know off line,  i.e. above
>address, and I will send it to you. I have sent a copy to Towney for the
>maintenance manual update, but you are welcome to it in the mean time.
>There are easy and difficult ways to do everything , and I hope I have
>figured out the easy or at least effective and not too costly ways for
>most of this.
>    And by the way, if you use 5200, (which I have done for this area
>too) you will need to let it cure for at least 48 hours and preferably
>for a week before you relaunch. Read the instructions for curing on the
>tube or package and follow those to the letter. I used a tube and a half
>to seal the stern tube area in #528. Because of the mass, and thickness,
>it takes the full time for curing. Getting air on the surface is easy,
>but the curing process has to work through the whole mass to get the
>chem reactions going all the way through. Don't rush it, because you do
>not need water pressure working on plastic areas (uncured material)
>within the mass that have not solidified. Getting these out of place
>because of  outside pressures  won't help to keep the water out. Thus
>this is a more time consuming job than you think it is , not necessarily
>because you have to work all that time, but wait for curing of materials
>you have no way to speed up. It took me about 6 hours to clean up the
>thiokol to my satisfaction - (remove cutlass bearing holder, prop shaft,
>and if you have a 3 blade prop, you need to remove that too as a 2 blade
>might just slip past the rudder, then clean up the thiokol.
>    Putting things back together takes only slightly more time than
>taking it apart because one needs to centre the stern tube on the shaft
>and the shaft needs to be aligned, so about an hour more by my methods.
>(The prop can be difficult to remove but is really easy to put back on
>so there may be time saved here.) Two people help for the re-assembly,
>not because the method is requiring strength, but eyes and hands inside
>the boat and outside sure cut down the running back and forth.
>Don #528
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