18SF tank size

[erebus]

Just yanked my tank out today and was surprised to find that it was only two thirds the size it could have been.



Did SeaCraft have any particular reason for this in the 18 footers?
Would it be detrimental for me to have a tank made to accommodate the entire space? I imagine I could pick up some range that way, but also some weight.
It is down low though.

Anyone out there who's rehabbed an 18 want to weigh in?