JPK 960

Sailboat specifications

The JPK 960 is a 31’6” (9.6m) cruiser-racer sailboat designed by Jacques Valer (France). She was built since 2003 (and now discontinued) by JPK (France).

JPK 960's main features

Model: JPK 960
Hull type: Monohull
Category: Cruiser-racer sailboat
Sailboat builder: JPK
Sailboat designer: Jacques Valer
Country: France
Construction: GRP (glass reinforced polyester):
Sandwich fiberglass polyester (vacuum infusion)
First built hull: 2003
Last built hull: Discontinued
Appendages: Keel : fin with bulb
Helm: Single tiller
Rudder: Twin transom hung rudders
Unsinkable: No
Trailerable: No
EC design category iThe CE design category indicates the ability to cope with certain weather conditions (the sailboat is designed for these conditions) A: Wind < force 9, Waves < 10m B: Wind < force 8, Waves < 8m C: Wind < force 6, Waves < 4m D: Wind < force 4, Waves < 0,5m: A
Standard public price ex. VAT (indicative only): About
81 500 €
(2006)

JPK 960's main dimensions

Hull length: 31’ 6”9.6 m
Waterline length: 28’ 2”8.6 m
Beam (width): 11’ 5”3.48 m
Waterline beam (width): 8’ 1”2.48 m
Draft: 6’ 5”1.95 m
Light displacement (M_LC): 7496 lb3400 kg
Ballast weight: 3086 lb1400 kg
Ballast type: Cast iron fin with lead bulb

JPK 960's rig and sails

Upwind sail area: 603 ft²56 m²
Downwind sail area: 1313 ft²122 m²
Mainsail area: 344 ft²32 m²
Genoa area: 258 ft²24 m²
Symmetric spinnaker area: 818 ft²76 m²
Asymmetric spinnaker area: 969 ft²90 m²
Rigging type: Sloop Marconi 9/10
Mast configuration: Keel stepped mast
Rotating spars: No
Number of levels of spreaders: 2
Spreaders angle: Swept-back
Spars construction: Aluminum spars

JPK 960'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.: 267 ft²/T24.77 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.: 581 ft²/T53.96 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.: 151
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.: 41 %
Prismatic coefficient iThe prismatic coefficient is obtained by dividing the volume of the boat (mass divided by the density of water) by the waterline length multiplied by the area of the maximum transverse section. This coefficient describes the effectiveness of a sailboat for a certain speed range: lower is the coefficient (<0.45), more effective the yacht is below its hull speed; higher the coefficient is, more the boat is suitable for planning speed.: 0.55
Maximum righting moment iThe righting moment is a moment (torque) that tends to restore a boat to its previous position after heeling. Its value corresponds to the torque needed to heel the boat for this angle. Higher the righting moment is for an angle, greater is the stability.: 21699 lb.ft3000 kg.m @
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.: 7.12 knots