Here are the measurements and images detailing a ca1950 Thompson Hiawatha with narrow ribs: Serial number (on stern stem only) appears to be DX 11631 but the 116 is questionable. Will need to confirm when I strip the interior. ID plate on bow deck has no number nor does the original bow stem. LOA 16' Tip to tip of outside stems 176" Max beam (tumblehome) 33" Max beam of outwales at center thwart 32" Inside beam inwale to inwale at center thwart 28-1/8" The following lengths are referenced from the tip of the bow outside stem (hook of tape wedged between stemband and OSS): Tip to leading edge of bow seat frame 49-1/2" Tip to CL of bow thwart 63-1/4" Tip to CL of center thwart 88-7/8" Tip to CL of stern thwart 114-1/8" Tip to leading edge of stern seat frame 132-1/2" CL of center thwart is slightly offset toward stern by about 3/4". I'm not sure if this was intensional, accidental, or just poor measuring on my part. CL of either qtr thwart is approx 25-5/8" from CL of center thwart Thwarts are 2-1/8" x 3/4" stock, 27" longest dimension of qtrs, center thwart is 29-3/4" long Decks are 14" from tip to tail measured along the sides, tail is 6-7/8" wide Seat frames are 3/4" stock x 1-3/4" for long rails and 3" wide for side rails, dowelled construction, machine cane held in place by an inner frame Bow seat blocks are 2-1/2" x 10-1/4" Cane openings measure approx 6-1/2" x 10" Thwarts and seats fastened using steel round head slotted machine screws. When I removed the stern seat to inspect how it was put together all 4 nuts sheered off. Another tidbit: under each deck is a brass strap running across under the deck from inwale to inwale. Hope this data helps! Someone who has seen more Thompsons needs to chime in on the seats - original or not? Seems rather unique construction. More pictures to follow (6 image limit).