Tuesday, January 11, 2011

What did we get for our Money?

A sistership undersail
Dimensions, Capacities, Etc - Hunter 460 (as per the Owners Manual):

LENGTH OVERALL (LOA)………………………….. 44'3" 13.49m
LENGTH OF WATERLINE (LWL)………………….. 38'8" 11.79m
BEAM (MAX)…………………………………………..14'0 4.27m
DRAFT ..........................……………………………5'6" 1.68m
DISPLACEMENT…………………………………….. 28.000 lbs. 12,698 kg
BALLAST ...........................………………………..9,500 lbs. 4,309 kg
SAIL AREA (100% TRIANGLES)……………………908.1 sq. ft. 84.4 sq.m
SAIL AREA (ACTUAL W/STANDARD SAILS)…….1155 sq. ft. 81.29 sq.m
I………………………………………………………….55.26 ft. 16.84m
J ……………………………………………………….. 7.16 ft. 5.23m
P…………………………………………………………50.42 ft. 15.37m
E…………………………………………………………17.91 ft. 5.45m
MAST HEIGHT (FROM WATERLINE)………………62' 9" 19.13m
HEADROOM…………………………………………..6'6" 1.98m
WATER CAPACITY…………………………………..200 U.S. gal. 757 liters
HOLDING TANK CAPACITY………………………...50 U S gal. 189 liters
FUEL TANK CAPACITY……………………………..100 US gal. 378 liters
LPG TANK CAPACITY……………………………….10 lbs. 4.54 kg
BATTERY CAPACITY………………………………..75 amp (1) start battery
180 amp (2) HOUSE BATTERIES
ELECTRICAL VOLTAGES…………………………..12 V.D.C./ 110 V.A.C.
(SELECT OVERSEAS MODELS 220 V)
INBOARD ENGINES………………………………….76 hp 37.3 kw
76 hp OPTIONAL 47.3 kw OPTIONAL
OPTIONAL GENERATOR……………………………6 kw
MAXIMUM LOADING…………………………………10 people 2460 kg (including luggage)
LIFTING POINTS………………………………………indicated by "sling" labels on hull
PROPELLOR ……………................................... 3 blade driven by a YANMAR 4JH2HTE (turbocharged H.P.) 18" X 17 R.H.(457.2mm X 431.8mm)

View over boatyard in BVI
Capsize Screening Formula (result should be less than 2) = beam/cube root of (displacement - in pounds - divided by 64) = 14/cube root of 28000/64 = 14/cube root of 437.5 = 14/7.6 = 1.84.

Displacement Length Ratio = (long) tons/(.01 x LWL in feet) cubed = 12.5/(.01 x 38.67) cubed = 12.5/.3867 cubed = 12.5/.0578 = 216.  Boats with a D/L ratio of more than about 325 are heavy cruisers. A number between 200 and 325 indi­cates a light- to moderate-displacement cruiser, and less than 200 is very light displacement.

Ballast to Displacement Ratio:  Ballast/Displacement = 9500/28000 = .34 or 34%
Clean Lines
SA/D = sail area divided by (displacement in cubic feet) 2/3 = 908/437.5 squared then cube root of result = 908/cube root of 191406 = 908/57.6 = 15.76.  Sail area is the size of the mainsail plus the size of the foretriangle (the area bounded by the headstay, mast, and deck).  To find dis­placement in cubic feet, divide it by 64, then square the number and, finally, find the cube root.  A SA/D ratio around 12 indicates an extreme under-rigged heavy cruiser.  A ratio double that one is typical of racing boats, and most modern cruisers fall between the two extremes. You can carry all the sail you want for light air (so long as you can reef quickly).

Hull speed = 1.34 times the square root of LWL  = 1.34 x square root of 38.67 = 1.34 x 6.2  = 8.3 knots

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