I also would not drill into the hull for this. I epoxied a thin piece of PVC to the hull (with pre-drilled holes for the pump) and then just attached the pump to it. It's been there for several years now, with no issues.

________________________________
From: Rhodes22-list <rhodes22-list-bounces at rhodes22.org> on behalf of Joe Dempsey <joedempsey at hughes.net>
Sent: Sunday, October 10, 2021 6:00 PM
To: rhodes22-list at rhodes22.org <rhodes22-list at rhodes22.org>
Subject: [Rhodes22-list] Hull Thickness

I'm looking for the thickness before I drill the mounting screws for the
pump. I want to mount it in the lazarette in the lowest location on the
centerline. The discharge will be above the water line.