The Standard Horizon HX400 is a handheld submersible VHF marine radio noteworthy for its exceptionally large battery although it does not float: I wanted extended usage between recharges more than I wanted flotation.
I've only broadcast on it long enough to check with the St. John's Newfoundland coast guard to see if it transmitted, and it did. It also received a few transmissions from others so I have to think it will serve well overall.
The only way I had of checking battery life was to let it run non-stop while broadcasting the NOAA weather channel reports and on two occasions it went well over 24 hours before the battery ran down. Both times the battery indicator gauge showed a full battery until shortly before it quit. I also just left it on (with the squelch high enough to stop any static) on Channel 16 to see how long the battery would last and it at least 48 hours. You can expect the battery to last at minimum of a week if you don't have it on and I imagine it would go a lot longer than that - I just haven't tried it.
It comes with both AC and DC (automotive plug) chargers and a better than average instruction manual. I'd been looking at radios for a while thinking I didn't want to spend any more than I had to but in the end paid only $165 shipped at gpsdepot.com, fully $30 less than Amazon so I went with this higher end model. It has a three year warranty and although I haven't had occasion to use it my perception is that Standard Horizon is the type of company that will stand behind its products.
It's got a lot of features (including a weather alarm which was triggered by reports of flash flooding near my home) although basic operation is relatively simple compared to many of the ridiculously complicated 'over-engineered' electronic devices extant today.
It's heavier than some I believe due to the large battery but there are always compromises.
All in all I'm happy with it.
