bedding external chainplates

[sailboy21]

I finally got sick of replacing one after another 304 stainless carriage bolts, so I'm going to pull the chain plates off, rebed and replace with 316 hardware. Question is, how should I goop them up? Spread the caulk out all over the backside and wipe up the extra? seems like this might get messy! Also, with some the the carriage bolts I have already replaced I noticed the old glassed in chain plates might also be corroding inside the laminate. Any way to address this? My plan is to make sure the caulk doesn't seal off the inside of the boat so that there is some ability for breathing.
Any problem with life caulk for this application?
Thanks

[mhfowle]

We use lifecaulk for almost all hardware bedding at the boat shop where I work. Just cover the chainplate, mount and tighten it, then wipe caulking that squished out with a rag with paint thinner on it. Life caulk is a great product!

[Faster]

Trace the outline of the chainplates and mask it off (wiht about 1/16 in clearance) before calking and installing the plates. That way the stuff that gooches out is easily removed and none of it will stick to the hull.

Wipe it off with a soapy finger to create a nice fillet before removing the tape, you'll have a good clean edge

[sander06]

From what I've read you should only seal the actual bolt attachment points and leave the rest of the chain plate back exposed to prevent corrosion due to lack of oxygen getting to the back of the plate.

[sailingdog]

Sander-

If the chainplate is clean and the sealant actually seals to it, the corrosion problem is minimal. IIRC, the oxygen deprivation corrosion problems require moisture to be present, particularly a problem when saltwater is trapped against the surface. That wouldn't be the case with the chainplates, and IMHO they're going to suffer less corrosion if fully sealed off using sealant.

Sailboy-

Don't forget to run a countersink bit over the bolt holes in the hull. This will give the sealant a place to form a natural o-ring type seal and will help keep them from leaking for a long, long time. Faster's advice on masking off the area is excellent and the way to go.