How to estimate a boats size?? Help!

Hi guys.I have a photo of an old fishing boat below.Been trying to figure out the size of it based on known dimensions and wondering if anyone out there would be able to help?I know the kegs on the front deck are 32" tall and the lifering on the bridge is 18" diameter..Any way to find the boats length (stem to stern,not counting pulpit or knee brace) based on these dimensions?Thanks

 

37 feet 6 inches & 11/16ths.
give or take 2 foot 6inches & 9/16ths

 

You already have a 32" scale. rotate 90 deg. & step off the boat boat length. But, using your scale, the windshield glass appears only 16" high????.
40'-8 1/8" (12.399m)

 

39 ft measured off the keg

 

Tried rotating the barrel and measuring it against the length and Im getting about the same numbers as you guys (38.5-40)..Since the barrels are sitting back a ways at the boats center line,would I get a more accurate number if I were to measure it from the stem to center of the transom,as oppose to the outside of the transom,where its longest ?
see pic
(I apolgize if Im not confusing anyone.)