Sounds scary to me. That stuff BONDS! Working the halyards may mean they
aren't anchored to the mast, but if the line is adorned with blobs, it
probably won't pass thru the sheaves freely.

When I spoke of the continued, forcible expansion, I was referring to the
cans labeled "minimal expansion."

Roger

http://home.earthlink.net/~derbyrm

wrote in message
oups.com...

snip
Now, for using expanding foam to silence internal halyard slap:

With mast down drill holes at 3' intervals, make the holes about 1/4"
to avoid stress cracking around smaller holes. Inject enough expanding
foam. While it sets over a few hours, work the halyards back and
forth.