I really like the frames Guy builds at whitewatermachine works. They are light, strong, stiff, adjustable, affordable, and hard anodized.
I have 3 of his frames and I can't find fault.
I think I'd stick with a 3 bay on a boat that size, but that's just me. I prefer a frame shorter than the flat section so I can adjust where frame sits on the boat, and have room for passengers etc ...
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