Apart from not having a clearance to land on ships which must be a requirement for SAR Ops down south.
Is this a recent change; I've landed on a ship/boat on more than one occasion in the early 90s? (NI and Belize). Come to think of it, we did quite a lot of SAR (standby) in Belize, but I accept the winch was somewhat cumbersome. Furthermore, I'm sure the Puma was designed to fly nice and fast and not spend too long in the 'OGE' hover!