Rebedding Ports

[jamato323]

My new (to me) CP 25 has water staining around two of its eight bronze ports. I was told the frames should be removed, old sealant removed and rebedded in 5200. I've read Don Casey on the subject but is there com-pac specific knowledge I should have?
Thanks

[Salty19]

Hi Jamato,

5200 is a very strong adhesive first and foremost, it's secondary function is a sealant.  Be aware if you bed anything in 5200, it's going to be on there for good.  It will be a bear to remove next time-in fact it will probably pull the glass out along with the port next time.  I would not use the stuff in this application...down the road it may leak again or you may have to replace them for whatever reason. 

3M 4200 would be a better fit me thinks.  Or any 50 year type household window sealant.  just be sure there is no silicone in it.    That would remain flexible, hold up to UV, be removeable down the road and get the job done at hand.
DAP makes a few sealants that would work well (available at the big box hardware stores).

[bmiller]

Salty hit it right on the head.

[Shawn]

As an alternate option consider Butyl tape. I just switched to it from the 4200/5200 and so far am very impressed with it. Much easier to apply, easier to clean up, never hardens, much easier to remove later. I think it also ends up being cheaper over time since you can keep using the roll years later until you run out. With 4200/5200 every time you need to bed something you end up buying a tube of it which has to be used with 48 hours.

http://www.pbase.com/mainecruising/rebedding_hardware

Shawn

[Bob23]

That was a cool little site, Shawn. I never thought of butyl tape but it makes perfect sense. I agree that 5200 is way overkill...meant for below the waterline use. I used some Dap 3.0 on my teak rebedding project this spring...had some leaks that I never had with good old bedding compound so I'm gonna remove 'em and start over again.
Bob23
Where do you buy your butyl tape?

[brackish]

Hey it moves!  different coefficients of expansion for different materials. Bronze has one, GRP has another, temperature cycles will make them both expand and contract but at different rates.   The idea isn't to stop them from moving (impossible) with a strong adhesive, the idea is to seal it with something that lets each move at their own rate and still seal.

Hey thanks for the site Shawn.  Break the edges on all kinds of things to avoid cracking.  GRP no different.

[Shawn]

Hi Bob,

They guy that put that site together ended up buying a bunch of butyl tape and sells it.

http://www.pbase.com/mainecruising/butyl_tape

I bought two rolls. I used the butyl tape on the Gooseneck wire passthrough and the Charlie Noble. Wish I had it last year when I pulled off all the teak, I used 3M which is going to make it much harder to get off in the future.

Shawn

[ciswindell]

I got butyl tape from an RV store for very cheap.  I think it was $3 for a huge roll.  I used about 2 rolls rebedding every piece of hardware on the deck.  That guy is not doing you a favor by selling you two rolls for over $30.  Keep in mind that a lot of RV places use a different, no butyl kind of tape that can cause staining, so make sure you ask specifically for the gray butyl tape.

Chris

[wes]

Just curious - why "just make sure it has no silicone in it"? I always use exterior silicone caulk for home projects (windows, shower stalls etc.) because of superior adhesion and longer life, and the exterior stuff is obviously going to be exposed to UV. I know it's not paintable, but why would this be a problem for rebedding portlights?

- Wes

[jamato323]

Thanks for your good suggestions 5200 will stay in the shop.
http://mobilehomepartsstore.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=403311

[Salty19]

Wes--Sure, silicone sealer/chaulk for the house works well.  The reason you don't use it on a boat is that permeates the gelcoat and glass and is tough to completely remove. A thin film will remain attracting dirt, staining the area and leaving a long term slippery spot where it touches. That means paint and other adhesives won't work there.  Not to mention all the spots you accidentally touch with a drop of the stuff on your finger.   

On my old 16, I put a small amount of silicone on two small bolts which filled holes where a compass had been not knowing the effects.  Within a year, a gray spot the size of an outstretched hand appeared around the two bolts.  Also a few other spots where I accidentally touched.  It came off after a lot of scrubbing with solvents eventually (repeated applications).  Or did it?   Check some other boat forums about it for many horror stories!

No offense to Don Casey but do not use 5200 if you can avoid it or if you really want it stuck for good. I noticed too in his solar charging "technical" article it completely left out the charge controller--a needed item to eliminate overcharging. No setup should be without one.    Bob Burgess he ain't.