Kingfisher 20+

1967 — 1978
Designer
R.A.G. Nierop
Builder
Westfield Engineering Co. (Marine) Ltd.
Association
Kingfisher Yacht Owners Assoc.
# Built
?
Hull
Monohull
Keel
Twin
Rudder
?
Construction
FG

Dimensions

Length Overall
21 7 / 6.6 m
Waterline Length
19 3 / 5.9 m
Beam
6 11 / 2.1 m
Draft
2 3 / 0.7 m
Displacement
2,900 lb / 1,315 kg
Ballast
1,100 lb / 499 kg (Iron)
Drawing of Kingfisher 20+

Rig and Sails

Type
Sloop
Reported Sail Area
177′² / 16.4 m²
Total Sail Area
?
Mainsail
Sail Area
?
P
?
E
?
Air Draft
?
Foresail
Sail Area
?
I
?
J
?
Forestay Length
?

Auxilary Power

Make
?
Model
?
HP
?
Fuel Type
?
Fuel Capacity
?

Accomodations

Water Capacity
?
Holding Tank Capacity
?
Headroom
?
Cabins
?

Calculations

Hull Speed
7.2 kn
Classic: 5.88 kn

Hull Speed

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.

Formula

Classic hull speed formula:

Hull Speed = 1.34 x √LWL

A 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

7.19 knots
Classic formula: 5.88 knots
Sail Area/Displacement
13.9
<16: under powered

Sail Area / Displacement Ratio

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.

Formula

SA/D = SA ÷ (D ÷ 64)2/3

  • SA: Sail area in square feet, derived by adding the mainsail area to 100% of the foretriangle area (the lateral area above the deck between the mast and the forestay).
  • D: Displacement in pounds.
13.93
<16: under powered
16-20: good performance
>20: high performance
Ballast/Displacement
38.0
<40: less stiff, less powerful

Ballast / Displacement Ratio

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.

Formula

Ballast / Displacement * 100

37.95
<40: less stiff, less powerful
>40: stiffer, more powerful
Displacement/Length
181.2
100-200: light

Displacement / Length Ratio

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.

Formula

D/L = (D ÷ 2240) ÷ (0.01 x LWL)³

  • D: Displacement of the boat in pounds.
  • LWL: Waterline length in feet
181.19
<100: ultralight
100-200: light
200-300: moderate
300-400: heavy
>400: very heavy
Comfort Ratio
17.0
<20: lightweight racing boat

Comfort Ratio

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.

Formula

Comfort ratio = D ÷ (.65 x (.7 LWL + .3 LOA) x Beam1.33)

  • D: Displacement of the boat in pounds
  • LWL: Waterline length in feet
  • LOA: Length overall in feet
  • Beam: Width of boat at the widest point in feet
16.95
<20: lightweight racing boat
20-30: coastal cruiser
30-40: moderate bluewater cruising boat
40-50: heavy bluewater boat
>50: extremely heavy bluewater boat
Capsize Screening
1.9
<2.0: better suited for ocean passages

Capsize Screening Formula

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.

Formula

CSV = Beam ÷ ³√(D / 64)

  • Beam: Width of boat at the widest point in feet
  • D: Displacement of the boat in pounds
1.94
<2: better suited for ocean passages
>2: better suited for coastal cruising

Notes

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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