Page 21: of Marine News Magazine (June 2022)

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The two primary bene? ts of increasing above two drive- lines are: • Graceful degradation – if a boat with two engines loses one shaftline, odds are it will not accelerate through hump. If a boat with more than three engines loses one shaftline, odds are it will be able to accelerate through hump and attain planing speeds. • Increased Availability – With multiple shaftlines the smaller equipment is more affordable. It becomes possible (although maybe not palatable) to maintain spares on hand, enabling an approach of maintenance by replacement.

IMO III and EPA 4 requirements are driving commer- cial operators to adopt this approach to keep propulsion engines under 600 BKW (800 BHP) of rated output. In the case studies that I’ve examined in the past, I’ve found that the equipment costs are similar between the two differ- ent scenarios (this is without considering the cost of the ex- haust after treatment now required on the larger engines).

The point is there are lots of people exploring the bene? ts on increased quantity instead of size—so should you.

Twin Disc