The theoretical maximum speed that a displacement hull can move efficiently through the water is determined by it's waterline length and displacement. It may be unable to reach this speed if the boat is underpowered or heavily loaded, though it may exceed this speed given enough power. Read more.
Classic hull speed formula:
Hull Speed = 1.34 x √LWLA more accurate formula devised by Dave Gerr in The Propeller Handbook replaces the Speed/Length ratio constant of 1.34 with a calculation based on the Displacement/Length ratio.
Max Speed/Length ratio = 8.26 ÷ Displacement/Length ratio.311
Hull Speed = Max Speed/Length ratio x √LWL
A measure of the power of the sails relative to the weight of the boat. The higher the number, the higher the performance, but the harder the boat will be to handle. This ratio is a "non-dimensional" value that facilitates comparisons between boats of different types and sizes. Read more.
SA/D = SA ÷ (D ÷ 64)2/3
A measure of the stability of a boat's hull that suggests how well a monohull will stand up to its sails. The ballast displacement ratio indicates how much of the weight of a boat is placed for maximum stability against capsizing and is an indicator of stiffness and resistance to capsize.
Ballast / Displacement * 100
A measure of the weight of the boat relative to it's length at the waterline. The higher a boat’s D/L ratio, the more easily it will carry a load and the more comfortable its motion will be. The lower a boat's ratio is, the less power it takes to drive the boat to its nominal hull speed or beyond. Read more.
D/L = (D ÷ 2240) ÷ (0.01 x LWL)³
This ratio assess how quickly and abruptly a boat’s hull reacts to waves in a significant seaway, these being the elements of a boat’s motion most likely to cause seasickness. Read more.
Comfort ratio = D ÷ (.65 x (.7 LWL + .3 LOA) x Beam1.33)
This formula attempts to indicate whether a given boat might be too wide and light to readily right itself after being overturned in extreme conditions. Read more.
CSV = Beam ÷ ³√(D / 64)
KINGFISHER 20 (Mk1) 1959 to 1959. Sail Numbers 1 to c.6
Keels moulded out of fibreglass as part of the hull. Transom hung rudder, large transom locker, engine well with removable seat sited at aft end of cockpit, fore hatch on the fore deck
KINGFISHER 20 (Mk2) 1959 to 1967. Sail Numbers c.6 to 267
Cast Iron keels. Later versions housed the engine in the transom locker using a pivot method similar to the 20+. Otherwise as per the K20 (Mk1).
KINGFISHER 20 Fin Keel. Year and Sail Number unknown
One produced and exported to Scandinavia.
KINGFISHER 20+ 1967 to 1978. Sail Numbers 268 to 464
Rudder shaft inboard through the transom, engine on swivel mechanism within the transom locker, hinged fore hatch located on fore cabin roof. There is also a long cockpit version primarily designed for the American market. Extra 70lbs of weight.
KINGFISHER 20+JR 1975 to 1978. Sail Numbers as K20+ but with JR at the end of the number. Sail number. 414JR is the oldest member number, 412JR being the earliest I’‘m currently aware of.
As 20+ but junk rigged. Fore hatch back on fore deck because mast stepped though the fore cabin roof. Came with either standard windows or portholes.
KINGFISHER 22 1978 to 1981. Sail Numbers 465 to x
This is identical to the K20+ except for a change in appearance when marketed by Kingfisher Yachts. The renaming to K22 was directly related to the boat length of 21’‘7” . This model was listed in the P.B.O. guide to yachts in 1978 as the Hasler KINGFISHER 22.
KINGFISHER 22JR 1978 to 1981. Sail Numbers as K22 but with JR at the end of the number.
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