I expressly wanted a single engined boat for simplicity and economy. My dream boat was a Nordhavn 62, and they only come with one main engine,,,perfect! A few years down the road now, I have changed my mind. If I was building a new build, and money was no object, I’d spec twins.
During our Pacific crossing from San Diego to Hawaii, I could not shake the inherent stress of 'What happens when the the big beast stops?' Turn on your wing engine right? Yeah, well I tried that, and she pushes us along smartly at 2.8 knots. That’s it. We could probably do 3 if we kept the peddle to the metal but that would not be sustained, and would also be foolish. So 2.8 knots it is.
INFINITY has 4 engine’s. Main, wing, and two generators. My imaginary lottery win (Nordhavn 76) would also have 4 engines, 2 Mains, and two generators, so in reality, no additional equipment or maintenance regime is required. At least with twins, your spares inventory could be streamlined down a bit as you now have common equipment.
With twins, you have a second engine on permanent standby, all the time, as it’s appropriately sized and spec’d as primary propulsion, not just emergency propulsion. Of course we all understand that twins are not as economical, nor as protected as singles, but I have found the following;
this marginal economy gain in a single is the last thing you are concerned with. If you are the type of person who lovingly cares for their vessel, (with the associated costs) then the price of diesel is certainly tertiary. You will have much bigger fish to fry.
our previous twin engined Cruisers 5000 (go-fast boat) never suffered any issues with PNW logs/debris. We may have been lucky, but it just wasn’t an issue. I’m a Nordhavn fan, so my next trawler (lottery win) will also be a Nordhavn, and the twins they spec appear just as ‘protected’ as the single is. They can also sit on their own bottom if required.
Our N62 has a single Lugger 6125A (Komatsu block) with 8353 hours on her and she purrs like a kitten, and I’m convinced she’ll never stop. But why then would I want twins, given the choice?
Neither boat is good-or-bad, each will safely take you wherever you want to go. It just boils down to what you (the Captain) feels comfortable with. It’s more a ‘piece-of-mind’ thing as others have stated.
Have fun out there - & Happy New Year!