On Jul 8, 8:54*am, " wrote:


Hi Tom,

You caught me in an usually benovolent and kind mood today........

Below is a post from 2005 that may be of help:


Hello:
Any thoughts on this.
Chainplates are a source of leaks and equal source of debate on how
to
fix the leak.
Some people say use polysulfide because if you use 3M5200 you'll be
tearing your boat apart to rebed plates in a few years.
Others say the reasons why plates leak is because polysulfide do not
have required strength. The only way to solve plate leaks is to use
3M5200. Why? It has a much stronger bond.
Others say that 3M5200 loses its bond eventually and it too will
leak.
Only this time the boat owner has a major problem removing the old
adhesive to rebed.

Here is the question....... Why would 3M5200 bond fail?


I called 3M tech people and they sent Tech Data Sheet (effective:
12/1/2004). Interesting data.
I also called Royal Adhesive and received data for Silaprene.
This is what I read.


Stainless to Stainless Overlap Sheer Strength
3M5200.........352 psi
Silaprene......488 psi


Interesting.


What about temperature. I was painting my garage last summer. Ambient
temp was 94 degrees F. I hung a thermometer on the side of the garage
in direct sun. Temp of garage wall was 150 degrees F. OUCH!


How hot do chainplates and decks get in many parts of the world
during
the hot season? 130-150-180F? Just a guess. How does temperature
effect
plate adhesive bond? I got more TDS stuff.


3M data: (Service temperature -40F to 190F) "Heat resistance-Due to
the decreased value in bond strength at elevated temperature, we do
not
recommend use of this product above 190F."


Silaprene data: (Service temperature -60F to 250F) " Heat
resistance-No significant loss of bond strength until 300 degrees F."


Elevated Temperature Shear Strength
3M5200......................(70F = 240psi) (150F = 176psi) (190F =
139psi)Teak
test substrate.
Silaprene.............(70F - 250F)No significant shear strength loss.
READ THIS AGAIN !


Question. Could 5200 fail because deck and plate temperatures reduce
its bond strength?


Has anybody used Silaprene?


Comparing data each company supplied says Silaprene has greater bond
strength than 5200 on stainless steel and keeps its strength at
temperatures when 5200 begins acting like butter (exaggeration).


Ideas about the deck temperatures causing 5200 failure
Should I use Silaprene to rebed my chainplates "forever?"

Bob