the 1959 Crestliner V-hull that I have has the full length ribs also.
but, in the center, there is about 1/8" gap for water drainage.
If your boat has several layers of paint, perhaps these drain places may have
been closed up with paint ????
check closely with a small knife or screwdriver.
if you do have those drains, they are very easily blocked with the smallest leaves, etc.
if you do have them, get them unclogged by whatever means works; paint remover, etc.
then, be careful not to park your boat where it can accumulate dirt, leaves, trash, etc.
until you get your deck engineered to have adequate drainage.
Plan "B" would be to build your deck accordingly to allow ventilation as well as water drainage
and when you park it, put the tongue up as high as you SAFELY can . . . .
a serious thought would be to put a float activated bilge pump in the bow for hard pouring down
rain, should you ever encounter one. And, bilge pump in the back also - - -
Plan "C" is to get a waterproof cover for it when parked.
I never decked my Crestliner. I just tolerated the very small amount of water that gets
trapped between the ribs as some of the drains were painted shut.