Ted Brewer's 'Comfort Ratio'

JBJag27 said:
. . . I note that my boat (a Catalina 27 variant) scores 24, about the same as a Beneteau Oceanis 393. From this I would suggest that the number isn't a lot of practical use.
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You have to read what Ted says about the application of his 'Comfort Ratio' . He says it's for comparing boats of similar size. It was never intended to compare a 27 footer and a 39 footer.

He said it showed the 'corkiness' of a hull which is its quickness of motion in waves and is primarily a function of the waterplane area and its displacement. He also cautioned against using it to compare boats with very differing waterplane shapes as the formula only an estimates waterplane area and isn't really applicable to very wide sterned boats.

The notion of the comfort ratio was first suggested it in a magasine article as a bit of fun. The fact that the formula has gained traction shows that when used correctly, it can give an insight into highlighting one particular characteristic of boats.
 
Motor_Sailor said:
You have to read what Ted says about the application of his 'Comfort Ratio' . He says it's for comparing boats of similar size. It was never intended to compare a 27 footer and a 39 footer.

He said it showed the 'corkiness' of a hull which is its quickness of motion in waves and is primarily a function of the waterplane area and its displacement. He also cautioned against using it to compare boats with very differing waterplane shapes as the formula only an estimates waterplane area and isn't really applicable to very wide sterned boats.

The notion of the comfort ratio was first suggested it in a magasine article as a bit of fun. The fact that the formula has gained traction shows that when used correctly, it can give an insight into highlighting one particular characteristic of boats.
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'Quickness of motion' may be the key.
If you look at the design of small heavy-weather fishing vessels, they are not designed to resist rolling, but they are designed to roll at a low frequency.
It is a big subject which some yacht design books touch on.

A yacht in reality resists rolling not just by ballast, but by the forces the keel will exert if you try to roll it quickly. Consider a dinghy with no ballast.
It will tip quickly if the centreboard is retracted, more slowly if it's down.
It can be much more stable when moving at speed.
OTOH appendages like fin keels also transmit energy from waves to the motion of the hull. So in some conditions they may damp the motion, in others they may drive the motion.
Likewise the sails. Most yachts are more comfortable sailing than motoring in my view.
A hull that is prone to slamming is not IMHO comfortable particularly if you are below trying to cook or use Jabsco's finest porcelain.

Personally I think a boat which is more comfortable in e.g. Solent conditions, might be less comfortable in long offshore waves.
Also cats can have a particularly uncomfortable motion in some seas, I have known people puke on cats in conditions which would not trouble them on a monohull. True to a lesser extent of boxy, hard-chine vessels?
 
Achillesheel said:
Achilles 24, comfort ratio 100.55? I don't think so, must be a decimal point error somewhere......
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Indeed, I got 132 with the figures I used, but maybe I was slightly off. They rather unhelpfully don't specify units, so I selected metric and assumed SI.
 
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