I have had great luck with the Rule Auto pumps going back to the 90's on all my different boats, airboat to offshore. I have tried all kinds of different float switch solutions and all of them have failed me at some point due to clogging, age etc. The Rule pumps kick on every 2-3 minutes, if the amperage draw is too low (no water) they shut right back off. They have 3 wires, ground, auto and manual. I wire the auto mode to my main power switch and the manual to a separate switch. My hulls stay dry with these pumps.
Page 5 of this link shows the 2,000 GPH we put in one of our boats. Sure glad we went over kill when we split the hull and had to run 15 miles back to the ramp.
I run the 500 GPH automatic unit on my deck over (I'm adding a 300 back up). I punched a decent size hole in the hull a few years ago and didn't realize it for months until I was sitting in water and saw the pump turning on/off. On my old offshore boat I had 300 GPH automatic units everywhere, including hull back up and 2x in the aluminum engine bracket.