I've had two Islander Bahama 30s, the first with an Atomic 4, the current with the original Volvo MD7A. The Volvo ran strong but was corroding from the inside (raw water cooling). I have just repowered with a Beta 20 on a new Sea Prop 60 sail drive unit (comes as a package from Beta). I chose a Beta 20 over the 13 and 16 as I wanted three cylinders for a smoother running engine. I have been very pleased with the results to date. There is an annoying ticking noise at idle that Beta is still working to correct, but the basic package has worked out very well. With the Beta all the service points are at the front (with the exception of the fresh water cooling system zinc) which makes working on the engine in the tight B30 compartment easy. I posted a daily log of how I did this re-power on the Islander 36 Association website (Islander 36 Maintenance
) under Propulsion Systems/Natasha Engine Replacement. It's a bit long and includes redoing the bottom and electrical, but does include photos of the new engine base and compartment. The document also includes the decision making process for selecting the Beta 20 and saildrive combination.