I find that I agree with much that has been stated above. As a point of reference I have done a lot of off shore diving frome my Boston Whaler 22 Dauntless, with up to four divers aboard (Tech gear and 2 steel tanks each). While we ventured as much as 20 miles off shore, this is alawys a risk and took much planning and coordination to ensure safety. If you stay within 10 miles of shore a well equiped center console single engine boat will do, but if you want to get out past that 26+ feet and twins is really what is needed. I am on the water almost every day and see divers and fisherman out well past the prudent limits of their vessels, this is always a risk and sometimes does not end well. While there are many very good used boat deals to be had, 30k is a bit on the low side unless you hunt a great deal. Good luck!