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Old 06-22-2021, 10:29 PM   #9
City: Newport, R.I.
Vessel Name: Hippocampus
Vessel Model: Nordic Tug 42
Join Date: Jul 2020
Posts: 3,278
What’s not mentioned is two key factors.

Displacement. A 48’ trawler may be quite significantly more efficient in moving the same weight when operating within its design parameters.

And speaking of water pushed aside. Prismatic coefficient, lwl, wave piercing or bulbous bow, parasitic drag and so many other factors effect fuel burn. So the geometry of the hull effects efficiency as well.

If you’re going to compare boat efficiencies LOA may not be the best the fixed parameter. A narrow, light long hull of for X displacement operating below hull speed is very much more efficient than a heavy beamy boat which would have much less lwl at the same displacement.
Rather would think displacement is a more meaningful one or total contained volume. Hence the half ton or one ton ratings for some old school sailboat races. In powerboats engines run constantly well below their HP ratings may be less efficient and even with common rail enhancements have less service life.
Wrote this as slowgoesit posted. He’s right. Get the boat that makes you smile.
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