Technique or Board problem?

Hey guys!
I'm a relatively new surfer, been going at it for about 5 months now. I get out roughly 4-5 times a week, Age 24, 6'2 194lbs fairly athletic. Got basics down on the Infamous Costco wavestorm, been riding a 10'2 log recently practicing bottom turning, going down the line, weight shifting, cross stepping, and have been catching unbroken waves with a fair amount of success.
My issue: Decided to try out a smaller fun-board shape and picked up a used 7'6 x 22-3/4 NSP off of Craigslist. The board had some chew on the rails and gel-coat damage on the board but other than that the board was in great shape considering the price. Was told it was water-tight, and the guy at the shop said he surfs it frequently and it was great for what I was looking for. Took it out(albeit not on a great day) and tried it out, for some reason the tail just bogs down on take-off, and to actually ride(not sink) I had to stand on the front 1/3 of the board. Even then the tail would sink when I got to a flatter section. Am I not doing something right? Why won't the tail lift? Is it likely the board has taken on water in the tail, and that's what's causing this?
Any help much appreciated!
Thanks- Mark
I'm a relatively new surfer, been going at it for about 5 months now. I get out roughly 4-5 times a week, Age 24, 6'2 194lbs fairly athletic. Got basics down on the Infamous Costco wavestorm, been riding a 10'2 log recently practicing bottom turning, going down the line, weight shifting, cross stepping, and have been catching unbroken waves with a fair amount of success.
My issue: Decided to try out a smaller fun-board shape and picked up a used 7'6 x 22-3/4 NSP off of Craigslist. The board had some chew on the rails and gel-coat damage on the board but other than that the board was in great shape considering the price. Was told it was water-tight, and the guy at the shop said he surfs it frequently and it was great for what I was looking for. Took it out(albeit not on a great day) and tried it out, for some reason the tail just bogs down on take-off, and to actually ride(not sink) I had to stand on the front 1/3 of the board. Even then the tail would sink when I got to a flatter section. Am I not doing something right? Why won't the tail lift? Is it likely the board has taken on water in the tail, and that's what's causing this?
Any help much appreciated!
Thanks- Mark