I once made a small boat for my son out of 4 inch PVC drain pipe.

The boat looked like a small pontoon boat 12 feet in length. I found that the
boat was quite stable and seaworthy. Unfortunatly it could only carry my son at 100 pounds. A 1 foot section of pipe would be half submerged with a 3.5 pound load.

The pipe becomes very brittle (like a christmas ornament) at cold temperatures.
The boat shattered when someone stepped on it in January (Wisconsin!).

Beware!!!

Rick