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 Sloop
version is offered with a classic masthead Marconi sloop rig.
is as well listed, on Boat-Specs.com, in Ketch
version (see all the versions compared
Longbow's main features
Hull and deck: GRP (glass reinforced polyester)
Number of hulls built
First built hull
Last built hull
Keel : fin without bulb
Single rudder on skeg
Standard public price ex. VAT (indicative only)
Longbow's main dimensions
31’ 2”9.5 m
31’ 2”9.5 m
9’ 6”2.9 m
4’ 6”1.38 m
Mast height from DWL
41’ 7”12.67 m
Light displacement (MLC)
8378 lb3800 kg
3990 lb1810 kg
Longbow's rig and sails
Upwind sail area
540 ft²50.2 m²
207 ft²19.2 m²
334 ft²31 m²
237 ft²22 m²
152 ft²14.1 m²
61 ft²5.7 m²
Sloop Marconi masthead
Deck stepped mast
Number of levels of spreaders
1x19 strand wire continuous
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.
222 ft²/T20.61 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.
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.
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.
Longbow's auxiliary engine
1 inboard engine
Longbow's accommodations and layout
Closed aft cockpit
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