As luke says the buy and sell can be good for bargains but as you said this is your first boat buy which is why i didnt recommend it, ya get a lot of
"yeah its spotless" and after a long journey to get to see it your usually let down.
The orkney strikeliner,longliner,fastliner are semi displacement hulls which are slower moving boats,. Although fine safe boats.
heres a longliner
heres one with a cuddy
heres a strikeliner
heres a fastliner 19ft
And finally heres a 520, you can see the different shape/slope degree on the hull.
The 520s hull is more sloped which is faster as it cuts through the water better, ie get further quicker.
I personally think a fastliner 19 with cuddy would be a ideal boat if there is three or more of you with plenty of space and stability.
Its nice to be important , but its more important to be nice.