The very first step and most important is to clean everything.
Remove all of the old sealant from the deck and hardware. Then
clean both with acetone. Relax, take your time. A little extra
care, a little extra attention to detail will add years of
waterproof service to the job.
Now here is the simple secret to a great looking job. Put
everything back together (dry fit) and then put masking tape
around the hardware. The masking tape makes it easy to remove
the excess sealant and get a clean professional looking
Ok, now take it all apart again and apply a 1/16 to 1/8 inch
coating of sealant. Go all the way to the edge of the tape. It's
better to apply too much than too little. If you don't get an
even coating it will leak and then you get to do it over and
over until you get it right. Apply too much and you just have a
little more clean up, but the tape makes clean up a snap.
Reassemble everything. Only tighten the screws enough to
just squeeze the sealant out the edges. Don't tighten the screws
all the way. You are creating a gasket with the sealant so you
want 1/16 inch or so of space under the hardware filled with
Let this stand overnight. Don't rush it, let the sealant cure.
Silicone will set in an hour or two but you can leave it for
24 hours without any problems.
After the sealant has cured tighten the screws. If you see
sealant squeezing out the sides like toothpaste you're rushing
it. Wait a while longer.
Finally for a great looking job carefully cut the sealant
down to the tape all the way around the hardware with a sharp
knife or razor blade. Pull the tape off and clean up with a
little soap and water. You're all done and you have a great
looking installation that should last for years.