The bottom line is there are a lot of trawlers and other types of power boats cruising around the world right now with single screws. There are trade
offs with both and yes, you should and will learn to work on your diesel
is not a consideration then you could go with twins, but you will be cutting in your navigational range by half since I would guess there is no opition for more fuel
tankage. On the other hand you will be able to go faster, if that is your goal.
is being considered, twin engines will double your fuel and maintenance
bills. Not to mention the initial outlay of funds for the second engine.
Bow and maybe a stern thruster, as well as a good prop walk, will compensate for close quarter manuvering on a single screw. So manuverabilty is normally not an issue when considering twin or single screws.
If you are worried about only having one engine, I would find out if they have the option of a take off unit on the Gen Set to be used as a "Get Home" motor
. These are normally very slow as compared to the main engine (3 or 4kts), but does give you a back up, while you repair the main engine.
When I convert from sail to a power boat
, mine will be a single screw with a bow thruster and a "Get Home" take off from the Gen Set.
Good luck with your purchase!