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Old 02-04-2019, 06:35 AM   #11
Fish53
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City: Rockport
Vessel Name: Ana
Join Date: Jul 2015
Posts: 1,047
Quote:
Originally Posted by FF View Post
"And no they don't all roll abominably and in general make a better seaboat."

All boats will roll , for a Seakindly ride the question is not how far but how fast and how does the roll check and reverse.?

Happily to some extent this can be tested before purchasing.

With slack lines in a slip or anchored a boat can be rolled by simply moving from rail to rail. The roll period can be timed (usually about 4 seconds or so) and how the roll stops and reverses can be felt.

A quick roll with a hard check can create a vomitorium in a beam sea.


A full displacement boat is seldom bothered by the added weight of cruising gear , an added 2000 lbs of necessary stuff may add 3HP to the engine load or about 1/5 of a GPH.
Hence my word "abominably", all boats roll to some extent it's the nature of the roll that determines whether or not it's a comfortable roll. Here is a quote from Michael Kasten "Displacement vessels (sail or power) will usually have a less aggressive roll motion, a longer roll period, and a more gentle "return" at the end of the roll than semi-displacement or planing types. This is primarily due to displacement types having a proportionately less wide waterplane and greater displacement. We find that comfort and seakindliness are enhanced by keeping beam to the least amount necessary for initial stability and / or for sail carrying ability.
Conversely we observe that adding ballast will be counter-productive in terms of comfort.". I agree that you can get some idea of a vessels roll period at the dock as well as measure stability but at rest at the dock doesn't show the whole picture just a hint of what to expect at sea. I don't mind the motion of a full displacement boat with a round bilge but I have been on some downeast hulls that will jerk the coffee cup out of your hand in a beam sea.
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