Sealing Through-Hull Exhaust

[greg82255]

Hello,

I have a 1986 Formula 206 that has one of Formula's bolt-on swim platforms. There is about a 1 inch gap in between the swim platform and the boat's transom. I am installing a through hull exhaust and am trying to figure out how to seal the pipes properly. I know the pipes come with rubber seals that fit around them and are held in place by the mounting screws, but unfortunately that seal doesn't do much good for me. What I really I need to seal is the transom (see pic, the inner wall). How should I go about sealing this? I was thinking either put a large bead of 3M 5200 around the hole and then press the pipe in, or maybe putting flotation foam in the entire gap between the transom and swim platform so no water can get in there, and leaving the pipe as is. Any ideas as to which one is better? or any other thoughts? Thanks in advance.

 

[Bondo]

Re: Sealing Through-Hull Exhaust

Ayuh,... Don't use 5200.... They may have to come Out someday...

Is that a wet compartment,..??
How is it drained,..??

 

[greg82255]

Re: Sealing Through-Hull Exhaust

It's definitely a wet compartment. There's a gap between the swim platform and the transom and its not sealed in any way - that gap shown in the pic extends through the full width/height of the swim platform. I assume water just fills that area when the boat is in the water and drains when you pull it out of the water. I figured if I filled around the pipe with foam or sealant then water would still get in that area, just stay away from the pipes.

 

[Tahorover]

Re: Sealing Through-Hull Exhaust

I've been using silicone for the last 12 years.

 

[greg82255]

Re: Sealing Through-Hull Exhaust

Tahorover - Your setup is slightly different than mine - Silicone would work for the seal between the swim platform and the pipe itself. I'm trying to figure out how to seal the gap between the transom and swim platform around the pipe.

 

[cstrianse1]

Re: Sealing Through-Hull Exhaust

I know that this is an old thread, but I and trying to do the same exact thing with my Formula 206. I connacted formula and they recommend merc p/n 12648A2. http://www.mercruiserparts.com/Show_Pictures3.asp?dnbr=898117&ivar=images/COMMON/18053.png&inbr=12493&bnbr=105&bdesc=Transom+Exhaust+Kit(4+Inch)
I don't see how that will seal around the hole in the transom.
Thanks.

 

[Friscoboater]

Re: Sealing Through-Hull Exhaust

I've been using silicone for the last 12 years.

Please do not use Silicone. Silicone is for Houses, and has no place on boats. If you need it to be removable, you can use 4200. I used 5200 because I did not want it to ever come out.

 

[cstrianse1]

Re: Sealing Through-Hull Exhaust

I was planning on using 4200. My question is how do I seal the hole in the transom AND the swim platform. My one thought is to remove the swim platform; install the exhaust tip into the transom and seal the flange to the transom. Then I can reinstall the swim platform. I guess I would need to epoxy the plywood in the swim platform to that it doesn't rot. then finally I could put a decorative trim ring to make it look finished. Thoughts?

 

[Bondo]

Re: Sealing Through-Hull Exhaust

I was planning on using 4200. My question is how do I seal the hole in the transom AND the swim platform. My one thought is to remove the swim platform; install the exhaust tip into the transom and seal the flange to the transom. Then I can reinstall the swim platform. I guess I would need to epoxy the plywood in the swim platform to that it doesn't rot. then finally I could put a decorative trim ring to make it look finished. Thoughts?

Ayuh,.... That sounds like a reasonable plan....