I assume that your boat looks something like this . . . Non-folding seat.
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In general, it is a fairly big job. The back-2-back backrest looks like a single cushion, so that would need to be re-fabricated into 2 backrests.
Then there are hinges and rails. The base cushions would get mounted on sliding rails and the re-fabricated backrests would get hinged together. 3 hinges . . . 1 to attach the backrests and the other 2 to attach the backrest (lower portion) to each of the 'sliding' base seats.
Probably some fiberglass work to be done as well, since what is underneath the seats probably will have to change to some extent.
Are you good at metal fabrication? Are you good at fiberglass work? Are you good at upholstery work?
