[C320-list] Sealant/caulking

[Warren Updike]

I switched to butyl rubber tape a few years ago after reading advice from Maine Sail blog. Here is the article: https://marinehowto.com/bed-it-tape/ I used these techniques in rebedding chain plates, hatches, and other hardware. The chain plate effort was an experiment and so far it has worked well. There should be a bit on this topic in the Google archives.

Warren and Pattie Updike
1994 C320 "Warr de Mar" #62
Middle River, Chesapeake Bay

-----Original Message-----
From: Chris Burti [mailto:clburti at gmail.com] 
Sent: Monday, September 18, 2017 9:36 AM
To: 320
Subject: Re: [C320-list] Sealant/caulking

Let me pass on some tips for working with butyl tape.
1. When you need to make a joint, overlap it by the width of the tape. Then
cut across at a 45 degree angle, remove the triangle cutoff on top strip,
lift the top strip and remove the triangle waste on the bottom. This
creates a scarf joint that seals perfectly when the hardware is tightened
down. You can use this technique for square corners as well.

2. If you are having trouble with round corners, cut a three inch section
of tape and roll it in your hands like a noodle. Lay it down around your
curve and roll it flat with the beer bottle you just emptied. Scarf the
joints as above.

3. I  have awls in most of my several tool kits made from grinding a long
tapered point on old Phillips screwdrivers where the tips had broken or
worn down. Use one to make your hardware holes.

Fair winds,
Chris Burti
*Commitment,* #867
Farmville, NC


On Sun, Sep 17, 2017 at 9:51 AM, Dave Hupe <hoopdtwo at yahoo.com> wrote:

> I have used butyl tape, Dow 795 and several 3M sealants.......all this
> summer after having purchased our boat this April.
> I rebedded my center cabin Bomar hatch with butyl tape which worked very
> well.  However, it is hard to make 90 degree or curved corners.  I slightly
> overlapped the tape where I did the corners.  You need to be careful not to
> make the overlap areas too thick if you can't tighten hardware down enough
> to make sure everything seals when compressed. You might also be able to
> butt the tape tightly at transition points, since it should squeeze
> together at the butt edges and seal.
> I think butyl works good when you are dealing with smaller wood/sheet
> metal mount hardware that easily penetrates the tape during mounting.
> However, where you have large bolt type mounting hardware, you can't just
> lay the tape over the holes and punch the hardware through it.  So, it
> becomes tough to deal with properly sealing around the hardware.  That is
> why caulk type sealant may be better in such circumstances.
> I have used 3M products several times and am upset when I use very little
> and the tube hardens very quickly thereafter. It also dries essentially
> hard and can dry out over time. The Dow 795 sealant adheres extremely well,
> stays flexible/rubbery after curing, and has very good elasticity (so it
> can accommodate future "movement"/flexing without leaking).  The partially
> used tube can be sealed and it stays good for quite a while.
> Dave Hupe
> 1994 Cat320 (hull #32)
> Holland, MI
>
>
>