using arduino R3 in boat

Using Arduino Project Guidance
1

I have two questions :

1- can I use the boat 12v battery as power source without stepping it down to 9v for this arduino board?
2- how can I protect the board from the harsh salt environment ?

thanks

2

1.yes.
2. Use some spray on stuff called "conformal coat" that seals the board up.
Mouser carries several kinds.
http://www.mouser.com/Tools-Supplies/Chemicals/_/N-wp63?Keyword=conformal+coat&FS=True
When I was in industry, we used Urethane conformal coat for military sales CCAs.

3

thank you so much !

4

Be sure to cover up your header holes, reset switch, etc, if you don't want them gummed up.