There are some very good, environmentally friendly citrus based degreasers
that would do what you need, don't know how they react with paint or
gelcoat.
I used to use a product called "FSR" for fiberglass stain remover until I
found the active ingredient is oxalic acid. Now I buy "Wood Bleach" at my
local hardware for a fraction of the cost.
MMC
"Rick" wrote in message
...
After a beaching with Katrina and the refloating with Rita I am left with
a
boat with a brown scum smile on the side of the boat. The residue is from
mud mixed with oil and diesel from the sunken boats that were not so
lucky.

Question is cleaning the hull? My thoughts are open at the present time
and
am wondering if the groups experience base can help? Right now the boat
is
in the boat yard so access is fairly easy.