Tomcat transom leak

matt_unique · Posted: Sun Dec 13, 2009 11:58 am Post subject: Tomcat transom leak

I was looking over the inside of my transom today and noticed a leak. Here's a picture of the leak with the tell-tale mold following the apparent path of the water. If you are looking at yours, this area is just to the left of the hydraulic steering alignment valve. There is a hole you can see right at the top of the mold 'waterfall'. When I stick in a screwdriver I'm hitting metal. Using my screwdriver as a measuring stick, it appears to be dead center with my rub rail.

My starboard rub rail on the transom bows out just a little. It may be coincidence but I suspect this slight bow is allowing rain water to pool behind the rub rail and find it's way in through the penetration.

I know our transoms are cored, does anyone know if the transom is cored right where the rub rail goes in? How do you remove rub rail? I assume you need to remove the rubber insert somehow then remove the screws holding the rub rail frame. I've never done it before though so any advice is appreciated. Assuming the transom is cored where the rub rail attaches I would need to remove it, properly seal it, and reattach it of course.

On the portside of the transom I noticed a rust waterfall from the portside transom eye. I do not see any evidence of leaking on the inside of the transom. It may be a good idea to remove these eye's and properly seal them in the core as well.

My winter project list was almost complete for this year...better to find it and fix it sooner rather than later.

Thanks for the suggestions.

thataway · Posted: Mon Dec 14, 2009 9:01 pm Post subject:

Sorry to see that Matt. I don't have either of those problems. But you ask some very good questions. My transom is cored with foam. I had assumed that the top was solid, but it might not be, especially since you can stick a screw driver or ice pick in and hit metal. I'll try and look at mine in the AM.

The rub rail can be pried out--but I would heat it first to soften it slightly. Yes, there is an extrusion which is screwed into the hull. Often with this type of transom, the top part has the glass from the inside brought mate with the outside, so that the thickness would be the same as the top deck mold, and they would match, so that the hull and deck could be glass together. Now you have me very curious as to what was done here.

I have also wondered if there was a little water leak from the rub rail extrusion along my port side, since I do get a small amount of bilge water on the Stb--not much if any on the port side. None inside, where it is definately glassed. My boat is at a bit of an angle in the lift, so that little water would collect on the top of the rug rail aft.

matt_unique · Posted: Mon Dec 14, 2009 11:20 pm Post subject: Metal

Hi Bob,
I assume the metal I'm hitting from the inside of the transom is a screw or something coming in from the outside holding the rub rail to the hull. Am I understanding this correctly? Would you suggest removing the rub rail down to this point to inspect the hole/seal?

I actually notice these holes equidistant all along the inside of my transom but just this one is leaking. If these holes do coincide with screws or such from the rubrail, why would there be holes also on the inside?

Thanks

Sea Wolf · Posted: Tue Dec 15, 2009 1:13 am Post subject:

Matt-

You asked:

"If these holes do coincide with screws or such from the rubrail, why would there be holes also on the inside?"

I'm guessing it's because they just drilled them carelessly right though the hull all the way.

Installing the rub rails would be an easy job for a new, beginning worker, you'd think.

And a new worker, unless told specifically not to do it, might not think it would make any difference whether to stop at a given depth, or just drill holes plenty deep to put the screws in. Rolling Eyes

Stranger things have happened! Smile

Joe.

matt_unique · Posted: Tue Dec 15, 2009 9:34 am Post subject: Drill

lloyds · Posted: Tue Dec 15, 2009 10:52 am Post subject:

If it is like mine, the holes are drilled all the way through to accomodate rivets. The insert is actually pretty easy to take out and put back. Just use a hair dryer to soften it up a little.

Matt Gurnsey · Posted: Tue Dec 15, 2009 12:47 pm Post subject:

That looks like it might be a rivit. Pulling the rubber insert out of the rub rail will show whether you have screws or rivits holding the rubrail in place.

In either event, pulling the one fastener and reinstalling with sealant should solve the problem, and won't involve removal of the metal rubrail strip.

Tad and Toby Jackson · Posted: Tue Dec 15, 2009 12:52 pm Post subject:

Captain Matt,

On our 1995 22' Cruiser, the rub rail is attached to the boat with rivets. Over time, the rivets had corroded and broken free, allowing the rub rail to bow out and away from the hull. (I believe there were also some hard dockings that contributed to loosening of the rail.) I removed the entire rail after drilling out the rivets. I had to cut circular plugs of 5200 that covered the rivet caps on the inside. I used a thin walled piece of pipe to cut the plugs. After cleaning up the holes, I re-installed the rail with ss screws and washers and was able to draw the rail up tight to the hull. It is a much better way to attach than with rivets. I have the project documented in our album.

Good Luck...Tad

lloyds · Posted: Tue Dec 15, 2009 5:22 pm Post subject:

On my boat the rivets are covered by possibly 4200, something that is workable. So you can drill into the rivet from the outside and once through the outside can just push the rivet through to the inside. This spring when global warming reaches oregon I am going to replace the rivets with ss screws, and some more 4200 on the inside. I think I can do all the rivets on both sides in about three hours or so. That effort will make it better than new.

thataway · Posted: Tue Dec 15, 2009 5:41 pm Post subject:

I got a good chance to look at the inside of my transom and the rub rail today. The Admiral also offered her suggestions. I found only one rivet which I could see a small amount of, and that was back behind the seat--there were no visiable holes or signs of rivets in the areas around the lasarettes. When I have time I may take a fiberoptic scope or mirror and look behind the cockpit sides, where I suspect that it is less likely that the inside was glassed in. My boat appears as if at least one layer of glass tape was applied on the inside of the hull to deck joint in this area. The one rivet (where I also assume that the hole was drilled too deep) did seem to have some sealant--4200, 5200 or perhaps the dreaded Bostic?

There was no bulge or sign of water going under my rub rail, so I will do nothing. I know that the core is synthetic. There is no moisture inside or outside.

It was a bit disturbing that there was no end cap fitting over the rub rail. The rail was split in several pieces, but the joint was in the middle of hte hull, not on the transom. Putting the trim rubber back in, is easily done with a screw driver after warming the vinly. I have re done several of these rails. Silicone sealant can help prevent water from running behind the railing, but silicone is difficult to get perfect adhesion--especially where it has been used before. I would try it anyway.

Also no mold in this area on my boat. I do notice when I have the airconditioning on (all summer ) or heat (all winter) there is a convection flow of air in this area, which may prevent mildew).

matt_unique · Posted: Tue Dec 15, 2009 8:11 pm Post subject: Rivets

thataway · Posted: Tue Dec 15, 2009 9:33 pm Post subject:

We determined the core material when putting in the transducer cable hole in the transom.

You are correct that you can see a lot of the side area with the boxes out (they sould be siliconed or lifecaulked in)--but there are also some areas in the corners which need to be looked at with a mirror--or scope.

matt_unique · Posted: Mon Dec 28, 2009 4:34 pm Post subject: Update

Well we had some slightly warmer temps today so I decided to tackle the rub rail.

Removal of the rubber insert was a piece of cake. Warmed up the end with the blow dryer, 30 seconds later I removed it from mid transom to the starboard corner.

I definitely have rivets holding the rub rail frame. Most of the rivets do not go all the way through, but over my leak (referenced in the picture at the start of this thread) it was just wide open air (as is the case with several other rivet holes along my transom). I initially drilled with a small diameter bit but there was no resistance and no drilled material. Upon closer inspection it was just a wide open tunnel through the rivet. So...makes sense that water would simply run right through the rivet canal and down the inside of my transom and into the bilge.

I will say I was pleased with the gauge of rivet - they were the largest/thickest rivets I have ever seen. I used a large screw driver to push on the head of the leaking rivet to see if perhaps it was corroded and broken off or such - no evidence of being broken. The bowing of the metal rub rail frame I also reference above was due to the fact that they did not drill/place the rivet in the ideal spot to hold it perfectly flush right before the corner.

I'm wondering if there would be any value in removing the rivet based on what I observed and instead fill the hole with LifeCaulk or something. I'm also thinking of running a thin bead of something - perhaps LifeCaulk along the entire top and bottom of the rub rail. Thoughts?

Matt Gurnsey · Posted: Mon Dec 28, 2009 4:59 pm Post subject:

If the rivit "core" is not there, but the rivit itself is holding, I'd just seal the rivit with sealant and reinstall the rub rail. Easy fixes are best!

C-Bill · Posted: Mon Dec 28, 2009 5:59 pm Post subject:

That's odd!! My 1991 C-Dory Cruiser has the tip of a screw on the inside of the transom midway to the Portside. I recently noticed very minor leakage of water. On the outside, no screw head is visable. I have covered that portion of the boat for the time being.

Does the new C-Dory owner in Washington have an excellent reputation for fiberglass work?

Bill