1967 Starcraft resto, code name "On Holiday"

[dpotter]

I was thinking of putting some neoprene on the top of the new fuel tank to keep the floor from touching it. Came up with a new idea. Since I'll have to use 3/4 coosa for the transom, I can cut some thin strips of that and 5200 it to the top in several places. That allows me to make it the exact thickness I need. For those that don't know, Aluminum tanks have a bad rap for life expectancy. The real issue is that some boat manufactures let wood or anything that traps water touch the tank. What I'm doing is using 5200 to glue the tank to the ribs on the bottom. 3/4 air gap on both sides and as much air gap as possible on the top. If nothing holds water against the tank, it will last a very long time.

 

[dpotter]

Has anyone bought one of the stainless screw/bolt kits? If so what do you think? Are they the right sizes... Is this a good way to go or just keep some of the old ones and make a list to go buy the specific sizes?

 

[dpotter]

The previous owner drilled 2 holes in the side of the boat to mount the TNT pump. He I was thinking of just putting a round head SS bolt through the holes with a washer on each side and some 5200. Any better suggestions out there? Oh, didn't they do some fine work with the silicone? ha

 

[dpotter]

Transom is out. First I knew they were made of multiple parts.

 

[dpotter]

The main section is 1.5 inch cut at 16"'s with the upper corners grafted on. Appears to be original. the grafted pieces were lagged in with flat tip screws. I assume they were trying to optimize material.

 

[dpotter]

Ok, another question. When the new transom goes back in, is trere any sealant used on the sides and bottom? I don't recall seeing this in the rebuild threads.

 

[oldhaven]

Ok, another question. When the new transom goes back in, is trere any sealant used on the sides and bottom? I don't recall seeing this in the rebuild threads.

I assume you mean is the transom fastened in with some sealant in rather than just slid in and fastened. On my original there was no edge sealant or adhesive used, and the new rebuilds do not either. If you mean were the edges water sealed, the answer for the original seems to be no, but everyone doing plywood rebuilds recently seals the edges as best they can to prevent future water ingress. When I was going to use plywood I was going to drill drain holes in the z-channel the transom sits in so water would not collect there and cause corrosion, and I still may though I am using a composite. I will be coating the entire transom with some sort of paint or opaque sealer just because Coosa is not very nice to look at and may need some UV protection. I would guess you will be doing the same?

Ron

 

[dpotter]

Ron, I'm thinking a auto wrap material(vinyl). I haven't committed to it yet, but my desire is to have a lot of wood looking material inside. Yes, I am talking edge sealant. I don't want to use 5200, to hard to remove if needed. There are some sealants that could be put on the edges as the transom is being installed. That would keep water from being able to get between the coosa and the aluminum and into the hull. The vinyl would be the UV protection. My concern is that the vinyll has a 10 year life expectancy if kept uncovered. I have not researched coosa's paint adhesion. Have you? It's always possible to just paint the coosa to match.

 

[dpotter]

Ron, I assume the reason most don't (even the factory) use sealant to seal between the transom and the hull is the aluminum on the exterior. I suppose if that is truly sealed we should be fine. especially using coosa.

 

[oldhaven]

I think I misunderstood. Yes there I found an original gasket material and sealant between the transom and the splash well. That could be replaced with 3M sealant and I will be doing that for sure, as have others here. Good idea. 3M 4200 is less tenacious than 5200 but with any luck and unless you want to live forever you will not be the one removing the transom again. I recently had to remove 5200 adhered parts in my other project, and even that can be done, but not fun. As far as paint adhesion, my research indicates it will take any coating you want to put on it. Treat it as you would plywood. Since it won't rot, you could even put aluminum over the exposed portion above the splash well.
Ron

 

[dpotter]

Oh, the other thing I found was water seeping through the splash at the transom into the hull. That may be all that's needed is to seal that.

 

[dpotter]

Perfect, thanks Ron.

Doug

 

[oldhaven]

One last thought. Sealing under the transom cap at the top is probably a good idea, but I don't intend to seal the outer edges or bottom in the z channel. Water will get in there and if it just drains through and out the bottom, fine. What I do not want to happen is for it to sit in there getting corrosive because the bottom is sealed up. The composite transom won't rot, but my transom's aluminum is already showing bad corrosion from trapped water over the years and I want to keep that at a minimum. Think how flashing around a chimney works.

Ron

 

[dpotter]

One last thought. Sealing under the transom cap at the top is probably a good idea, but I don't intend to seal the outer edges or bottom in the z channel. Water will get in there and if it just drains through and out the bottom, fine. What I do not want to happen is for it to sit in there getting corrosive because the bottom is sealed up. The composite transom won't rot, but my transom's aluminum is already showing bad corrosion from trapped water over the years and I want to keep that at a minimum. Think how flashing around a chimney works.

Ron

Agreed, I hadn't thought about holes in the z channel. I think it's a good idea though. I may also cut the transom 1/16th or so shy of the bottom.

 

[Watermann]

You want that transom to be down tight on the Z channel.

After filling the transom skin pitting I would prime and paint it including the Z channel so that it has a barrier to the water. It's also a good idea to remove that Z channel if you have corrosion issues, mine was loaded with the white powder between them, not sure how so much could be in there. Yeah I know more solid rivets but both surfaces were painted, the Z bedded in 5200 and then riveted it back on.

Here's what my Chief's Z channel looked like. The white powdered corrosion was between the Z and the skin. No way to have done the job right without taking it off.

 

[dozerII]

I think I misunderstood. Yes there I found an original gasket material and sealant between the transom and the splash well. That could be replaced with 3M sealant and I will be doing that for sure, as have others here. Good idea. 3M 4200 is less tenacious than 5200 but with any luck and unless you want to live forever you will not be the one removing the transom again. I recently had to remove 5200 adhered parts in my other project, and even that can be done, but not fun. As far as paint adhesion, my research indicates it will take any coating you want to put on it. Treat it as you would plywood. Since it won't rot, you could even put aluminum over the exposed portion above the splash well.
Ron

I have found the best and easiest way to seal the splash well to the transom is 1/2" wide butyl tape you can pickup at any glass shop, inexpensive.

 

[dpotter]

Thanks guys. This site is great. Keeps us from going astray.

 

[dpotter]

Ok, they are out of stock on the Coosa. I do't really want to wait another month so I may go ahead with marine 3/4. That means I have to find something else to 5200 to the top of the fuel tank. I think the plastic cutting board material will work. Thoughts?

 

[dpotter]

Oh, the gluvit is on the way and we are supposed to have 2 days of mid-high 30's. Hopefully work will leave me alone for part of that. I'd like to get the inside cleaned out and layout the old bolts, make an inventory and get those coming or even pick them up at ACE.

 

[oldhaven]

Good advice from Dozer and Watermann. They have done it all before. I will follow their guidance in mine. I have the same white chalk oxidation between my Z channel and transom skin. I will remove it, the knee brace, and probably the side brackets that hold the transom in so I can get at all the areas that need clean up and to be neutralized and maybe coated. I have seen POR 15 used by someone. I will also have to fill some pitting and even a few through holes. Then there is the 1/8 plate I will be putting on the outside. Inside the skin, anyplace I can seal to prevent water from above I will do that, but leave the bottom of anyplace metal or wood are touching open enough to drain. If you end up using plywood, that is a pretty well documented job.

As for above the tank, I wonder if something that is more resilient or springy, but will still not absorb water would be better than a rigid strip of plastic. It would absorb any flexing of the boat and deck that might dent or work harden the aluminum tank otherwise. Maybe it would be best to not transfer deck loads to the tank at all and just fasten it to the stringers and ribs. Just my opinion though.

Ron