You don't need an engine. But if you're becalmed in Florida Bay, it comes in handy. Don't ask me how I know.

The other stuff becomes desirable if you want to extend your range. I'm pretty sure that H16s have sailed to Dry Tortuga and camped. They, of course, started the Worrell. However, that's a little too daring for me. If I'm out of sight of land, I'd like to have a weeks worth of food and water.