Longbow Ketch

Sailboat specifications

The Longbow is a 31’2” (9.5m) cruising sailboat designed by John Laurent Giles (United Kingdom). She was built between 1971 and 1980 by Westerly (United Kingdom) with 265 hulls completed. The Ketch version displays a divided sail plan guarantying less effort and better balance adjustment.

The Longbow is as well listed, on Boat-Specs.com, in Sloop version (see all the versions compared).

Longbow's main features

Model: Longbow
Version: Ketch
Hull type: Monohull
Category: Cruising sailboat
Sailboat builder: Westerly
Sailboat designer: John Laurent Giles
Country: United Kingdom
Construction: Hull and deck: GRP (glass reinforced polyester)
Number of hulls built: 265
First built hull: 1971
Last built hull: 1980
Appendages: Keel : fin without bulb
Helm: Single tiller
Rudder: Single rudder on skeg
Unsinkable: No
Trailerable: No
Standard public price ex. VAT (indicative only): N/A €

Longbow's main dimensions

Overall length: 32’ 6”9.9 m
Hull length: 31’ 2”9.5 m
Waterline length: 24’7.3 m
Beam (width): 9’ 6”2.9 m
Draft: 4’ 6”1.38 m
Mast height from D_WL: 41’ 7”12.67 m
Light displacement (M_LC): 8378 lb3800 kg
Ballast weight: 3990 lb1810 kg

Longbow's rig and sails

Upwind sail area: 533 ft²49.5 m²
Mainsail area: 150 ft²13.9 m²
Mizzen sail area: 54 ft²5 m²
Genoa area: 329 ft²30.6 m²
Solent area: 237 ft²22 m²
Jib area: 152 ft²14.1 m²
Stormjib area: 61 ft²5.7 m²
Rigging type: Ketch Marconi masthead
Mast configuration: Deck stepped mast
Rotating spars: No
Number of levels of spreaders: 1
Spreaders angle: 0 °
Spars construction: Aluminum spars
Standing rigging: 1x19 strand wire continuous

Longbow's performances

Upwind sail area to displacement iThe ratio sail area to displacement is obtained by dividing the sail area by the boat's displaced volume to the power two-thirds. The ratio sail area to displacement can be used to compare the relative sail plan of different sailboats no matter what their size. Upwind: under 18 the ratio indicates a cruise oriented sailboat with limited performances especially in light wind, while over 25 it indicates a fast sailboat.: 219 ft²/T20.33 m²/T
Displacement-length ratio (DLR) iThe Displacement Length Ratio (DLR) is a figure that points out the boat's weight compared to its waterline length. The DLR is obtained by dividing the boat's displacement in tons by the cube of one one-hundredth of the waterline length (in feet). The DLR can be used to compare the relative mass of different sailboats no matter what their length: a DLR less than 180 is indicative of a really light sailboat (race boat made for planning), while a DLR greater than 300 is indicative of a heavy cruising sailboat.: 277
Ballast ratio iThe Ballast ratio is an indicator of stability; it is obtained by dividing the boat's displacement by the mass of the ballast. Since the stability depends also of the hull shapes and the position of the center of gravity, only the boats with similar ballast arrangements and hull shapes should be compared. The higher the ballast ratio is, the greater is the stability.: 48 %
Critical hull speed iAs a ship moves in the water, it creates standing waves that oppose its movement. This effect increases dramatically the resistance when the boat reaches a speed-length ratio (speed-length ratio is the ratio between the speed in knots and the square root of the waterline length in feet) of about 1.2 (corresponding to a Froude Number of 0.35) . This very sharp rise in resistance, between speed-length ratio of 1.2 to 1.5, is insurmountable for heavy sailboats and so becomes an apparent barrier. This leads to the concept of "hull speed". The hull speed is obtained by multiplying the square root of the waterline length (in feet) by 1.34.: 6.56 knots