Not yet - the Scillonian 3, in service from 1977, is still serving the route. Appledore must have done a good job when it built her.
(Edit) Concerning stabilisers, she has them. It might be that they increase her draught, as I seem to recall she deploys them when the water is a certain depth. She usually runs into St Marys via the channel between the mainland and St Agnes, which is deep, but at certain states of the wind and tide can safely use the shallow channel north of the mainland, which saves time, and in come the stabilisers for that.
Mark
But Scillonian III is stablised. However, that can only reduce roll, rather than eliminate it, and as her roll does start off as "way too much" it's not going to end up as "not much".