The FCC has never type-accepted a radio that can transmit on both marine and aviation bands. I have radios that can do that, but like I mentioned I'm a ham and I know better than to transmit on those frequencies. My radios are locked (either by the manufacturer or by me) to be unable to do so.

SAR aircraft will almost certainly have marine radios aboard, where boats almost never have aviation radios. If you're not a pilot or a ham, the marine radio is a better bet. Not that it would do you any good in the interior.