Copain Keel and centerboard

Sailboat specifications

The Copain is a 17’2” (5.25m) cruising sailboat designed by Henri Amel (France). She was built between 1962 and 1968 by Amel (France). The Keel and centerboard version features a centerboard inside of a short fin-keel allowing shoal draft while maintaining upwind capabilities.

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

Copain's main features

Model: Copain
Version: Keel and centerboard
Hull type: Monohull
Category: Cruising sailboat
Sailboat builder: Amel
Sailboat designer: Henri Amel
Country: France
Construction: Hull and deck: GRP (glass reinforced polyester)
Number of hulls built: About 50
First built hull: 1962
Last built hull: 1968
Appendages: Centerboard : pivoting centerboard in the keel
Helm: Single tiller
Rudder: Single transom hung rudder
Unsinkable: Yes
Trailerable: Yes
Standard public price ex. VAT (indicative only): N/A €

Copain's main dimensions

Hull length: 17’ 2”5.25 m
Waterline length: 16’4.88 m
Beam (width): 5’ 11”1.8 m
Waterline beam (width): 5’ 4”1.62 m
Draft: 3’ 4”1.02 m
Draft when appendages up: 1’ 10”0.56 m
Light displacement (M_LC): 1058 lb480 kg
Ballast weight: 397 lb180 kg

Copain's rig and sails

Upwind sail area: 172 ft²16 m²
Downwind sail area: 269 ft²25 m²
Mainsail area: 75 ft²7 m²
Genoa area: 97 ft²9 m²
Solent area: 65 ft²6 m²
Jib area: 32 ft²3 m²
Symmetric spinnaker area: 194 ft²18 m²
Rigging type: Sloop 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

Copain'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.: 281 ft²/T26.1 m²/T
Downwind 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.: 439 ft²/T40.78 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.: 117
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.: 38 %
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.: 5.36 knots