Beta Marine

Beta Marine

Sailboat Specifications

Hull Type: Fin w/bulb & spade rudder
Rigging Type: Fractional Sloop
LOA: 40.00 ft
LWL: 35.78 ft
S.A. (reported): 959.00 ft²
Beam: 12.30 ft
Displacement: 11,900.00 lb
Ballast: 4,800.00 lb
Max Draft: 7.75 ft
Construction: Infused FG/Epoxy with balsa core.
Ballast Type: Cast iron fin/lead bulb
First Built: 2018
Builder: J Boats
Designer: Alan Johnstone

KLSC Leaderboard

KLSC Leaderboard

Auxiliary Power/Tanks (orig. equip.)

Make: Yanmar
Type: Diesel
HP: 30

Sailboat Calculations

S.A. / Displ.: 29.54
Bal. / Displ.: 40.34
Disp: / Len: 115.98
Comfort Ratio: 17.55
Capsize Screening Formula: 2.16
S#: 5.11
Hull Speed: 8.02 kn
Pounds/Inch Immersion: 1,572.50 pounds/inch

calculation mobile

2 nd ad half width

3rd ad full width

Rig and Sail Particulars

I: 51.41 ft
J: 15.30 ft
P: 50.00 ft
E: 16.64 ft
S.A. Fore: 393.29 ft²
S.A. Main: 416.00 ft²
S.A. Total (100% Fore + Main Triangles): 809.29 ft²
S.A./Displ. (calc.): 24.93
Est. Forestay Length: 53.64 ft

Sailboat Links

Designers: Alan Johnstone
Builders: J Boats
Download Boat Record:


The J/121 includes a water ballast system with a 104 gal (394 liter) tank on each side. This system allows up to an additional 867 lbs (approx) to the rail.
Some specs and photo are from a review by Adam Cort in Sail Mag. Feb 8, 2018.