I'm about to design and build a gear frame for my new raft. 14' 6" Wing with 21" diminishing tubes, 60" C to C tubes.
My current fishing frame is a 1.25" box store frame. I was going to modify it so I could use it for a gear frame and convert back as needed. However, now I want a winter project, frame and also a new trailer for the raft.
Frame, at this stage, is going to be a welded double rail with diamond plate. I'll buy dry box(es) and cooler and make the frame fit what I buy, probably a 4 bay but we will see.
From my research it appears 1.5" welded is needed on a cat and/or big water. With 1.25" you do have the ability of some interchangeability of box store parts. As this is a raft(and not a cat), and just 60" C to C, I'm thinking 1.25" will do me just fine even on roughest water. Is there an aspect of 1.5" that I don't know about that may make me go with the larger size material?