Sealing Cable Runs

[jr88fan]

I am in the process of installing a GPS/Fishfinder combo and the directions state to seal the area around the cable running through the transom with a marine grade silicone. From what I have read silicone is evil on boats. What is the best thing to use to seal this area? Thanks

 

[Boats-A-lots]

Re: Sealing Cable Runs

Hum, never read or heard that silicone is bad for boats. I think I have always used it on my boats.

 

[BobGinCO]

Re: Sealing Cable Runs

When my new boat had a leak, what did the manufacturer send me? Silicone. Really, it's OK.

 

[Home Cookin']

Re: Sealing Cable Runs

should be OK especially if it really is marine grade (or is that a gimmick to double the price?) AS LONG AS IT'S ABOVE THE WATERLINE.
So in your case, your cable will pass through the transom above; use 5200 or something similar below.

Silicon will eventually degrade so just check it every year or so. Above the line, the consequences of failed silicon, short term, are nothing. I use it where it doesn't matter if it fails.

 

[salty87]

Re: Sealing Cable Runs

3m 4200 is approved for below the waterline and not quite as tenacious as 5200.

silicone isn't bad for the fiberglass of the boat but it's bad for the boat once it degrades and leaks. i don't know of any that's approved for below the waterline. even though this cable won't technically be below the waterline it's close enough to warrant an approved product.

 

[JoLin]

Re: Sealing Cable Runs

IMO, there's a better way. Drill the hole larger than needed and pack it with epoxy (Marine Tex or similar). That'll waterproof the hole. Then redrill through the middle of the epoxy to the correct size. Feed your wire through the hole, and top it with a 'clamshell' fitting with the open end pointing downward.

http://www.iboats.com/Marine-Electr...n_category.f--session_id.640885465--view_id.5

Any caulking will eventually break down, so I try not to use it when there's a better alternative.

My .02

 

[Woodonglass]

Re: Sealing Cable Runs

The #1 reason for Transom Replacements is water penetration into the wood core via the holes from engine mounts and other mechanical fasteners not properly sealed. JoLin's method is one of the best ways to ensure that your transom is protected from water penetration. I would Highly recommend it. You can use cabosil to thicken the resin to peanut butter consistency to easily fill the hole and then redrill to the desired size. No worries after that.