On Sep 15, 1:18 pm, Matt Colie wrote:
Mike,
After reading everything and looking at the pictures, I guessing that
the stuffing box was bonded to the hull with something significant and
later patched with silicone sealer (bad idea).

This is going to be more work, but you will have a better chance.

Go to a real marine store or web site and buy a tube (10oz?)of 5200. It
isn't cheap, but it is the right stuff to use here.

Now take enough apart so you can go over every thing involved with a
good stiff and really nasty wire brush on a grinder (4-1/2 would do).
This is the only way you are going to remove the silicone sealant the
you and others have used. It all has to be gone - completely. You may
have to pull the prop shaft out of the engine coupling to do this job
right. If you do not do it right this time, I can promise you will
have another chance and probably pretty soon. (In other words - do it
right or store the boat on a hoist or trailer where it can't sink.)

Well, I just looked at your pictures again. You don't stand a
snowball's chance unless you pull the shaft out.

You will want to back off the stuffing box and use a file to clean the
burrs off the end of the shaft before you pull it through the packing in
the stuffing box - even if it is backed off.

Now, Once you are POSITIVE that all the silicone goo and stuff is
completely gone from both parts, practice assembling the whole affair
with out touching the mating surfaces with hands or letting those
surfaces touch other things (you will soon know why). You won't need to
get the shaft all the way home, but it will need to be in the flange -
no key is required at this time. You need to have the shaft in place
and through the stuffing box while the 5200 cures.

Have at lease one friend and a roll of paper towels handy.

Then, coat both parts with what looks like too much 5200 and start the
assembly. Once the shaft is in the flange, push the stern tube (that's
the part the stuffing box is attached to) into its place in the hull.
If 5200 doesn't come out all around it inside and out, pull it back up,
smooth out what is there, push what did come out back in and add more
where needed.

When you are sure that you have a good fill and the stern tube is in
place, you can smooth off the excess 5200 so it is not too ugly both
inside and out.

Now, go ahead, try to get your hands clean - I dare you.....
Then sit down have a beer and read again how long it will take the 5200
to cure. Give it at least that long. It may be awhile, but you won't
have to do it again - ever. Don't move the joint until it is a solid
cure - it is temperature dependent - if it is cold, don't rush it.

Only when the 5200 is completely cured can you put it all back together.
This would be a good time to tend to the stuffing box if it needs any
attention. You might have to tap the shaft back into the flange (not
uncommon) and do not forget to safety wire the set screw in the flange.

It is also smart to put either a shaft collar or at least a hose clamp
on the shaft between the flange and the stuffing box. This is just a
little trick to keep the shaft from escaping (and leaving a hole) if it
should come out of the flange.

3m-5200 is a tenacious adhesive sealant. Removing something bonded with
it is usually better described as destruction than disassembly (but that
is what you ant here). There is a release solution that arrived on the
scene a couple of years ago. Just remember that in case you should have
to take this apart because something got damaged.

Mastercraft is a solid and well made ski boat. It is well worth the
effort to to the job right.

Matt Colie



Mike wrote:
I have an old Mastercraft inboard ski boat that I need some help with
fixing. Where the shaft of the prop goes through the hull there is a
metal plate. The edges around the plate were leaking and it was
sealed with silicon. I cut out the gobs of silicon that were there
and found that the plate sits in a 1/2 inch trough in the fiberglass
hull. When the silicon was removed I can move the plate fairly easily
by hand, even lifting it up slightly. I replaced the existing silicon
with Goo marine sealant. I let the sealant set for 24 hours then
lowered the boat back in the water. My little leak turned into a
gusher.

How is this plate supposed to be secured to the boat? Do I just need
to do a better job with silicone? Is there some adjustment that needs
to be made to hold the plate on better? Should this have done over
with fiber glass?

I put photos of the plate and problem area he www.lyonsland.com/BoatLeak

Thanks for any help.

--Mike- Hide quoted text -

- Show quoted text -

Matt,
Thank you for the detailed information. This is type of information
I was hoping to get. I will go pick up my beer and 5200. You are
correct that the job has been done poorly in the past and I look
forward to having it done right.

Thanks again,
Mike