Here's a good link http://www.boatdocking.com/other/Mushing.html

"Diego" wrote in message
ups.com...
I have a boat with twin 350 hp Crusader gas engines. I would like to
cruise this boat between Florida and the Bahamas. It will be optimal
for me to cross the Gulf Stream at high cruising speeds to get out of
harms way, then reduce to a very slow speed when moving around the
islands in order to conserve fuel and increase my range. I've heard
that this can cause fouling of spark plugs. Has anyone tried this and
can comment on doing something like this? Does the plug fouling
happen over a lengthy period of time (weeks) or rather quickly (hours)?