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

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

Being no expert on that fitting, I'll make a guess. There may be
fasteners through the hull from the bottom, or, it is bonded to the hull.

Either way, the fix is the same. Remove the fitting, clean out all old
"goo" and replace through hull fitting using new polysuphide (sp) sealant.

You cannot EVER fix a leak by putting goo around the outside. Silicone
is a bad choice for below the hull fittings. Polysulphide has a life
span of 20 years. +/- How many of our boats are that old?

You may not nave to remove the shaft if you can slide the fitting aft
enough to get good access to the surfaces and rotate the fitting enough
to clean it properly.

My opinion here is that anyone who uses the term "goo" does not
understand the difference between the proper sealant for each job.

Jim

You may not nave to remove the shaft if you can slide the fitting aft
enough to get good access to the surfaces and rotate the fitting enough
to clean it properly.

Yeah, but if the previous owner gunked it up with goo, and this guy added
more, then it'll probably require a bit more than just 'cleaning it off'.

Then there's the question of the hull condition around that whole box. If
it's been leaking then it's likely that water has gotten into the layers of
fiberglass. It may require a fair bit of fiberglass work to remove the
damaged portions.

This also leads to dealing with making sure the prop shaft is properly
aligned. The tolerances are pretty important.

It may be best to get a fiberglass place to take a look at it and give a
quote for proper repairs.

"Jim" wrote
Polysulphide has a life span of 20 years. +/- How many of our boats are
that old?

I've never owned a boat newer than that.

My opinion here is that anyone who uses the term "goo" does not understand
the difference between the proper sealant for each job.

He may have meant Goop, which is a brand name sealer/adhesive that comes in
a marine version. I agree with your guess that there should be something on
the outside that that clamps that fitting to the fiberglass. Doesn't make
sense that it would just be held in with sealant, even good sealant.

On Sep 15, 12:56 pm, "Ernest Scribbler"
wrote:
"Jim" wrote

Polysulphide has a life span of 20 years. +/- How many of our boats are
that old?

I've never owned a boat newer than that.

My opinion here is that anyone who uses the term "goo" does not understand
the difference between the proper sealant for each job.

He may have meant Goop, which is a brand name sealer/adhesive that comes in
a marine version. I agree with your guess that there should be something on
the outside that that clamps that fitting to the fiberglass. Doesn't make
sense that it would just be held in with sealant, even good sealant.


You are correct, it was Goop, I forgot the p. I looked under the boat
for any sort of clap or bolt that would hold the plate in place but
didnt see on. However I did this while it was up on the lift and
didnt get under the boat and may have missed it. I couldn't believe
that this would be held on with just sealant. I will take a closer
look under the boat.

The photos I put online are after my attempted fix. I cleaned out the
old seal and applied the Goop around and under the plate but it was
not good enough.

I had not considered damage to the fiber glass. I think I am going to
have to take it apart and inspect everything. The area I was dealing
with didnt feel soft but I need to check under that plate.

Thanks,
Mike

Mike wrote:
On Sep 15, 12:56 pm, "Ernest Scribbler"
wrote:

"Jim" wrote


Polysulphide has a life span of 20 years. +/- How many of our boats are
that old?

I've never owned a boat newer than that.


My opinion here is that anyone who uses the term "goo" does not understand
the difference between the proper sealant for each job.

He may have meant Goop, which is a brand name sealer/adhesive that comes in
a marine version. I agree with your guess that there should be something on
the outside that that clamps that fitting to the fiberglass. Doesn't make
sense that it would just be held in with sealant, even good sealant.



You are correct, it was Goop, I forgot the p. I looked under the boat
for any sort of clap or bolt that would hold the plate in place but
didnt see on. However I did this while it was up on the lift and
didnt get under the boat and may have missed it. I couldn't believe
that this would be held on with just sealant. I will take a closer
look under the boat.

The photos I put online are after my attempted fix. I cleaned out the
old seal and applied the Goop around and under the plate but it was
not good enough.

I had not considered damage to the fiber glass. I think I am going to
have to take it apart and inspect everything. The area I was dealing
with didnt feel soft but I need to check under that plate.

Thanks,
Mike

You will have to sand off the paint and undoubtedly the filler the
manufacturer used to hide the fasteners.

If the fiberglass is damaged in any way, grind off the damaged glass,
build up new glass with WEST epoxy and layers of 6 oz cloth. Then grind
back to original surface.

Unfortunately taking it to a "professional" might not actually be taking
it to anyone who knows more than you. Some things you should/have to do
yourself. Then you will have a better idea of how to attack the other
things you will find.

You will need professional advise aligning the shaft.

All in all I'd say this might not be a very hard job. I'd bet the glass
id ok under all the previous sealing attempts.

All you get by using WEST epoxy is the name. Save yourself the money and
get ordinary epoxy, us composites is a good source. West doesn't make it's
epoxy, they just package it. Just like everyone else. People like dupont
actually make the stuff.

"Jim" wrote in message
...
Mike wrote:
On Sep 15, 12:56 pm, "Ernest Scribbler"
wrote:

"Jim" wrote


Polysulphide has a life span of 20 years. +/- How many of our boats
are
that old?

I've never owned a boat newer than that.


My opinion here is that anyone who uses the term "goo" does not
understand
the difference between the proper sealant for each job.

He may have meant Goop, which is a brand name sealer/adhesive that comes
in
a marine version. I agree with your guess that there should be something
on
the outside that that clamps that fitting to the fiberglass. Doesn't make
sense that it would just be held in with sealant, even good sealant.



You are correct, it was Goop, I forgot the p. I looked under the boat
for any sort of clap or bolt that would hold the plate in place but
didnt see on. However I did this while it was up on the lift and
didnt get under the boat and may have missed it. I couldn't believe
that this would be held on with just sealant. I will take a closer
look under the boat.

The photos I put online are after my attempted fix. I cleaned out the
old seal and applied the Goop around and under the plate but it was
not good enough.

I had not considered damage to the fiber glass. I think I am going to
have to take it apart and inspect everything. The area I was dealing
with didnt feel soft but I need to check under that plate.

Thanks,
Mike

You will have to sand off the paint and undoubtedly the filler the
manufacturer used to hide the fasteners.

If the fiberglass is damaged in any way, grind off the damaged glass,
build up new glass with WEST epoxy and layers of 6 oz cloth. Then grind
back to original surface.

Unfortunately taking it to a "professional" might not actually be taking
it to anyone who knows more than you. Some things you should/have to do
yourself. Then you will have a better idea of how to attack the other
things you will find.

You will need professional advise aligning the shaft.

All in all I'd say this might not be a very hard job. I'd bet the glass
id ok under all the previous sealing attempts.

On Sat, 15 Sep 2007 13:13:28 -0000, Mike wrote:

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?

Tough to say with all that silicome gunk in the images, but given your
description, I would think that there is more going on there than just
a simple sealing job. From the looks of it, that bilge has more
problems than you may think.

If I owned the boat, I'd remove it entirely and look at the glass
supporting it. You may have come rotten glass in that area - just
guessing here, but from the photos, it would appear that the area
around the stuffing box (which is essentially what that is) is soft.
Again, just a guess based on the images - I could very well be wrong.

If it's doing what you said it was doing, then I'd take a closer look
at the surrounding area for more information.