SailNet Community - View Single Post - The ratios and other numbers - can someone enlighten me or point me to a resource?
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Old 07-08-2008 Thread Starter
arbarnhart
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Quote:
Originally Posted by T37Chef View Post
Thanks - I did (pasted in below).

I am going to be uncomfortable in motion, probably hard to sail, capsize easily and never go 6 knots. I get the impression that the calculations aren't really made for small boats.

boatName=Newport 17
LOA=17.75
LWL=16.1666
beam=6.3333
displacement=1000
sailArea=147

displacementToLWL=106
Displacement to LWL: A medium value would be 200. 300 would be high (Heavy Cruising Boat) and 100 would be low (Ultra Light Displacement-ULDB). Boats with low numbers are probably uncomfortable and difficult to sail.

speed=5.39
Calculated hull speed.

sailAreaToDisplacement=23.52
Sail Area to Displacement: The sail area is the total of the main sail and the area of the front triangle. I cannot be sure that this datum was entered correctly for each listed boat. A racing boat typically has large sail area and low displacement. A number less than 13 probably indicates that the boat is a motorsailer. High performance boats would be around 18 or higher.

LWLToBeam=2.55
LWL to Beam: A medium value would be 2.7. 3.0 would be high and 2.3 would be low

motionComfort=7.89
Motion Comfort: Range will be from 5 to 60+ with a Whitby 42 at the mid 30's. The higher the number the more comfort in a sea. This figure of merit was developed by the Yacht designer Ted Brewer and is meant to compare the motion comfort of boats of similar size and types.

capsizeRatio=2.53
Capsize Ratio: A value less than 2 is considered to be relatively good; the boat should be relatively safe in bad conditions. The higher the number above 2 the more vulnerable the boat. This is just a rough figure of merit and controversial as to its use.

category=racer
Sailing Category: The four categories are racer, racer/cruiser, cruiser/racer, and cruiser in order of descending performance

ppi=366
Pounds per Inch Immersion: The weight required to sink the yacht one inch. If the boat is in fresh water multiply the result by 0.975. If you know the beam at the waterline (BWL) multipy the result by BWL/Beam.

-Andy
Newport 17 - "Kohanna"
At sea Darwin's hypotheses is the final arbiter of right of way.
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