Originally Posted by Razorbill RIBs
They had twin 50's when they first went on service IIRC then 60's....someone like Martin (mchappelow on here) is a mine of knowledge re all things Lifeboat and could give you the proper /actual specs, but with twin 60's should do 30 knotts...
I know this will really date me, but when I served on a 21 it had twin 50s. It did us pretty well at the time, but the move to 60s certainly improved it. 30kn may be a bit optimistic for an old boat, but 25+ should still be well within scope.
In your part of the world, twins gives good reassurance, and I agree with Chewy - 90s would work well when the time came to change