X-312 Fractional rigging

Sailboat specifications

The X-312 is a 30’4” (9.25m) cruiser-racer sailboat designed by Niels Jeppesen (Denmark). She was built between 1989 and 1994 by X-Yachts (Denmark) with 64 hulls completed. The Fractional rigging version features 7/8 rig and running backstays allowing finer sail trimming options and lower IOR rating.

The X-312 is as well listed, on Boat-Specs.com, in Mast head rigging version (see all the versions compared).

X-312's main features

Model: X-312
Version: Fractional rigging
Hull type: Monohull
Category: Cruiser-racer sailboat
Sailboat builder: X-Yachts
Sailboat designer: Niels Jeppesen
Country: Denmark
Construction: GRP (glass reinforced polyester):
Sandwich fiberglass polyester with galvanized steel frame
Number of hulls built: 64
First built hull: 1989
Last built hull: 1994
Appendages: Keel : fin without bulb
Helm: Single tiller
Rudder: Single spade rudder
Unsinkable: No
Trailerable: No
Standard public price ex. VAT (indicative only): N/A €

X-312's main dimensions

Overall length: 30’ 4”9.25 m
Hull length: 30’ 4”9.25 m
Waterline length: 24’ 7”7.5 m
Beam (width): 9’ 10”3 m
Draft: 5’ 7”1.7 m
Light displacement (M_LC): 7397 lb3355 kg
Ballast weight: 3638 lb1650 kg
Ballast type: Cast iron / lead fin

X-312's rig and sails

Upwind sail area: 567 ft²52.63 m²
Downwind sail area: 910 ft²84.55 m²
Mainsail area: 290 ft²26.95 m²
Genoa area: 276 ft²25.68 m²
Solent area: 240 ft²22.26 m²
Jib area: 184 ft²17.12 m²
Stormjib area: 61 ft²5.7 m²
Symmetric spinnaker area: 620 ft²57.6 m²
I iFore triangle height (from mast foot to fore stay top attachment): 34’ 10”10.6 m
J iFore triangle base (from mast foot to bottom of forestay): 10’ 6”3.2 m
P iMainsail hoist measurement (from tack to head): 37’ 1”11.3 m
E iMainsail foot measurement (from tack to clew): 13’ 6”4.13 m
Rigging type: Sloop Marconi 7/8
Mast configuration: Keel stepped mast
Rotating spars: No
Number of levels of spreaders: 2
Spreaders angle: 0 °
Running backstays: 1 set(s)
Spars construction: Aluminum spars

X-312's performances

IOR rating iIOR, or International Offshore Rule, was a measurement rule system used internationally for ocean racing. It allows boats of different sizes and designs to race each other fairly. Therefore, by comparing these values, we can have an indication of the relative speed of 2 boats.: 23.5
HN (French rating) iHN or "Handicap Nationale" is an empirical rating system used in France allowing various monohulls, of different sizes and designs, to race each other fairly. It is particularly suitable for cruiser and cruiser-racer. Therefore, by comparing these values, we can have an indication of the relative speed of 2 boats.: 18.0
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.: 243 ft²/T22.61 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.: 430 ft²/T39.99 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.: 225
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.: 49 %
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.: 6.65 knots