J/100 Shoal draft

Sailboat specifications

The J/100 is a 32’10” (10m) dayboat designed by Rod Johnstone (United States). She was built since 2004 (and now discontinued) by J/Boats (United States). The Shoal draft version features a shorter keel to grant access to shallow areas.

The J/100 is as well listed, on Boat-Specs.com, in Standard version (see all the versions compared).

J/100's main features

Model: J/100
Version: Shoal draft
Hull type: Monohull
Category: Dayboat
Sailboat builder: J/Boats
Sailboat designer: Rod Johnstone
Country: United States
Construction: GRP (glass reinforced polyester):
Sandwich fiberglass polyester
First built hull: 2004
Last built hull: Discontinued
Appendages: Keel : L-shaped keel (with bulb)
Helm: Single tiller
Rudder: Single spade rudder
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): N/A €

J/100's main dimensions

Hull length: 32’ 10”10 m
Waterline length: 29’8.84 m
Beam (width): 9’ 2”2.81 m
Draft: 4’ 6”1.37 m
Mast height from D_WL: 46’ 1”14.04 m
Light displacement (M_LC): 6504 lb2950 kg
Ballast weight: 2491 lb1130 kg
Ballast type: Lead

J/100's rig and sails

Upwind sail area: 478 ft²44.4 m²
I iFore triangle height (from mast foot to fore stay top attachment): 38’ 6”11.73 m
J iFore triangle base (from mast foot to bottom of forestay): 11’ 6”3.51 m
P iMainsail hoist measurement (from tack to head): 38’11.58 m
E iMainsail foot measurement (from tack to clew): 13’ 6”4.11 m
Rigging type: Sloop Marconi fractional
Mast configuration: Keel stepped mast
Rotating spars: No
Number of levels of spreaders: 2
Spreaders angle: Swept-back
Spars construction: Carbon fiber mast and aluminum boom
Standing rigging: Single-strand (ROD)

J/100'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.: 232 ft²/T21.59 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.: 121
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.: 7.22 knots