Picking a surfski - why do the think six and epic v9 feel so different

Im new to the sport. Up till now i've been borrowing a friends ski or paddling with them in there double but its time for me to get my own. On the advice of a few people i went and demoed some through a local shop (great experience). The ski's i demoed where the Epic V9. Think Six and Think Evo. I want something i can downwind in and that i wont grow out of immediately but also wont spend to much time swimming.
The Epic was awesome, it felt great and i felt really stable in it even having enough confidence to play on small waves from passing boats. I did come out when i started getting tired and was playing around but mostly managed to stay in for a good 6km of paddling.
The Think Six is a boat that seems to be comparative on paper and i thought would feel pretty similar but i couldn't manage to stay in at all.
Obviously i should steer towards the boat i felt better in but i would like to understand ski's enough to know what it was about the Think that made such a large difference. To me it felt like i was higher in the water on the Think's and i also found myself leaning back in them for some reason both of witch lead to a more twichy feeling. Is it just the cockipit shape of the epic works better or is there something else

V9 has a round hull in cross section. Six is more boxy and flat bottomed. Some prefer one or the other. Flat bottom boats have more primary stability but less secondary. Round bottom boats are more predictable in big messy conditions. Flat bottom boats will feel better in small annoying side chop. I like round hulls personally. I found the v9 to be among the very best downwind boats I have ever been in. It has beautiful manners on the wave.

surfski.info/forum/2-announcements/19885...k-six-v-epic-v9.html

Zach makes some good points that are really valuable to understand. I also prefer skis with round hulls. The worst ski I've ever paddled was the Think Zen. It has the flattest hull and the most boxy cross section I've ever seen on a ski. It is a nightmare in big, rough conditions. My favourite all round rough water ski is the Carbonology Sport Boost X LV. That ski has a very similar beam to the Zen but a rounded hull so it is completely different to the Zen. So confidence inspiring in rough and confused conditions. The V9 has a very slightly square cross section but nothing like the Zen. It is an excellent downwind ski if you are completely stable in it.
You say; "I want something i can downwind in and that i wont grow out of immediately but also wont spend to much time swimming." Just because you can put words into a sentence doesn't mean they make sense.
If you want to paddle downwind; you simply must have lateral and directional stability. If you think you will "immediately" "grow out of" a stable ski then you are kidding yourself. Have a look at some video of Boyan Zlatarev paddling his V8 or Oscar Chalupsky paddling a Nelo 520. A stable ski is the best investment you can make in your paddling development and it is a safe financial investment. When you can paddle a stable ski better than Boyan and Oscar; you will have no trouble selling that stable ski (probably to someone who has made the mistake of starting with a ski they "won't immediately grow out of").

"I did come out when i started getting tired and was playing around but mostly managed to stay in for a good 6km of paddling."
It is difficult to evaluate that experience without knowing the conditions.

If you are paddling a boat that you don't feel stable in, then you'll develop bad habits. Instead of reading waves, developing your forward stroke, you'll be constantly bracing, hesitating. You will be slower than if you were in a more stable boat. Your fitness won't develop as well as it could.

The Mocke brothers have a mantra "A stable ski is a fast ski", combined with "Never ever ever Never sacrifice stability for speed"

See this