Actual Lengths vs. Nominal

[DJE]

I'm new to wood boats and am currently looking at a handful of 17' and 18' late '40s through early '50s models. Ideally, I'd like to be able to store the boat in my garage in the offseason...which was unfortunately built for a couple of Model Ts and doesn't nearly work for current life. As I'm dealing with a very tight fit, I'm wondering how close the actual lengths are to nominal lengths- ie is a 1950 U18 Sportsman exactly 18'-0" from tip to stern or something else? Page 70 of the 1950 Fleet Brochure lists the shipping length as 18'-5" and beam as 6'-4". While I assume the shipping dimensions include something for the crate, the beam width matches the published beam width on page 8 of the same brochure...which seems odd. Can anyone shed any light on this?

 

[varnishandwaves]

The U18 Sportsman from 1950? The real hull length is roughly 18'2 from the front to the back, but that doesn't count any of the extra stuff you might bolt on. When they talk about shipping length, they usually add in things like the rudder or any parts that stick out