For 1956 Skagit followed up the success of their 20 Chinook express with the big open utility runabout, the Tyee 20 Sports Coupe. This was announced in the February edition of Sea magazine. Also, the SKagit 17 series and the 14 Cohoe were released. Notice the Tyee ad mentions the upcoming Cohoe.
The boats all had stout fiberglass stringers, unless they were an inboard in which case they had 4x12 engine bed stringers glassed into the hull on industry standard 22.5" centers.

Here's the earliest 1956 Skagit ad we know of, for the newly released Tyee 20. Lots of room in one of these, we have located at least two outboard Tyee models, and at least two inboard models. They were available with a convertible canvas top or a molded fiberglass removeable hardtop.