Thumbing a lift. Honduras.

I´ll be heading through honduras towards nicaragua soon and thought it might be cool to get out to the bay islands and see if I can get on a boat, most probably private, and go round the coast to say, bluefields or the corn islands of Nica. Someone told me that now is a good time of year to do this as there are many private yachts, particularly from the states heading south through the caribbean at this time. Obiviously i would need to pay or work or a combination of the two. Is there a specific marina I should head for in Roatan/Utila to find this lift. Does anyone reading this have any experience of doing this kind of thing and can offer me advice? Also, if I go out into international waters what is the immigration proceedure? Get a stamp of the habour master when I make landfall? I put this up on the honduras branch too.

Many thanks for any assistance you can give me.
Russ