Safety/Performance Figures for NA23/Spirit 23

The following data was generated by Carl Adler's Sail Calculator v2.72, which can be accessed by clicking here .

(Figures in parentheses are for the 23k and were entered manually into the calculator. If not present, they are the same as the 23)

North American/Spirit 23
LOA (length overall)
23 ft.
LWL (length at waterline)
20 ft.
7.92 ft.
Displacement (empty)
2800 lbs.  (3150)
Sail Area (with standard jib)
215 sq. ft.  (233.4)
Displacement to LWL
156  (176)
Hull Speed
5.99 (knots?)
Sail Area to Displacement
17.32  (17.38)
LWL to Beam
Motion Comfort
13.06  (14.69)
Capsize Ratio
2.25  (2.16)
Sailing Category

Expanation of  safety/performance figures (taken from Carl Adler's Sail Calculator web page

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.

Hull Speed: This is the maximum speed of a displacement hull. Some racers and lighter boats are able to achieve greater speed by lifting over the bow wave and riding on top of the water,that is, planing.

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.

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

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.

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.

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

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.

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