X#!&XX!! Watertank Lids

[P69]

The corners of square holes are weak points. Make sure they are well-rounded or cut circle/oval holes.  This is problematic in metal, but not sure how much of an issue it is with fiberglass.

[S/V AMITY]

A hard square corner in most any material is a concentrated stress point.  Water tanks with several hundred pounds of water sloshing around in them flexes them to a degree.  As mentioned above, good practice to radius the corners a bit if you can.  Can't hurt.

[Jordan]

Was rereading this and wanted to mention that we discovered additional inspection ports and a couple cubic feet of storage space if you take off the wood covering it completely.