I didn't think they made the V5 until 1978, and they made them with the 5 V's well into the 80's...... then at some point the shortened the 2 extra V's that ran all the way to the bow and they dropped the V5 moniker...but some of the extra features are probably there, like the beam being wider... and the stringers being taller and laid out different. The splash well on the V5 is totally different than the regular hulls in the 22 ft version... they actually have a hinged door on the inside portion of the splashwell....that folds in....since I have a 22ft version I know more about that model than I do the 14ft and 18 ft versions...I don't think the 18 ft V5 had a fold down splashwell door... and I don't know that they were any WIDER in the beam than the regular 18 ft version...but the 22 ft V5 was WIDER in the beam than the non V5 hull... ( I think they only went with 21 ft versions of the non V5 hulls in the years they made V5 hulls....ie in the early 70s I have heard of 22 ft holidays....
the stringer height is MUCH taller on my 22ft V5 than my 1970 21 ft Islander.......
In retrospect I think the hulls didn't change much, but the early 80's just called the models "V", if it had the V5 hull config. because the 1983 brochure clearly shows an islander with the extra chines all the way to the bow!!
bob