SB20 Specifications
Main Specs
| Length, m | 6.15 |
| Beam, m | 2.15 |
| Draft, m | 1.5 |
| Displacement, kg | 685 |
Classification
| Hull Type | Monohull |
| Type by Usage | Racing |
| CE Class | C - Coastal waters |
| Hull Material | Fiberglass / GRP |
| Design | Sport-Modern |
Rigging and Keel
| Rig | Fractional Sloop |
| Keel | Lifting keel |
| Max Draft, m | 1.5 |
| Sails | Jib 9.3m2, Main 18m2, Spinnaker 46m2 |
Cabins & Passenger Capacity
| Max People on Board | 5 |
Engine
| Engine Type | Outboard |
| Engine Power | 6 |
Manufacturer Information
| Shipyard | Devoti Sailing |
| Country | Czech Republic |
| Model | Sb20 |
| Designer | Tony Castro |
| Period of manufacturing | 2004 - now |
Technical Specs
| LOA, m | 6.15 |
| LOD, m | 6.15 |
| LWL, m | 5.5 |
| Sail Area (S.A.), m² | 27.3 |
| Ballast, kg | 510 |
Sailboat Calculations
S.A. / Displacement Formula
SA/D = SA (ft²) ÷ [Disp (lbs) / 64]^0.666
A sail area/displacement ratio below 16 would be considered under powered; 16 to 20 would indicate reasonably good performance; above 20 suggests relatively high performance.
SA/D = SA (ft²) ÷ [Disp (lbs) / 64]^0.666
A sail area/displacement ratio below 16 would be considered under powered; 16 to 20 would indicate reasonably good performance; above 20 suggests relatively high performance.
Ballast / Displacement Formula
Bal./Disp = ballast (lbs)/ displacement (lbs)*100
A Ballast/Displacement ratio of 40 or more translates into a stiffer, more powerful boat that will be better able to stand up to the wind.
Bal./Disp = ballast (lbs)/ displacement (lbs)*100
A Ballast/Displacement ratio of 40 or more translates into a stiffer, more powerful boat that will be better able to stand up to the wind.
Displacement / Length (LWL) Formula
D/L = (Disp / 2240) / (0.01 × LWL)^3
The lower a boat’s Displacement/Length (LWL) ratio, the less power it takes to drive the boat to its nominal hull speed.
less than 100 = Ultralight; 100-200 = Light; 200-275 = Moderate; 275-350 = Heavy; 350+ = Ultraheavy;
D/L = (Disp / 2240) / (0.01 × LWL)^3
The lower a boat’s Displacement/Length (LWL) ratio, the less power it takes to drive the boat to its nominal hull speed.
less than 100 = Ultralight; 100-200 = Light; 200-275 = Moderate; 275-350 = Heavy; 350+ = Ultraheavy;
Comfort Ratio Formula
Comfort ratio = Displacement ÷ (.65 × (.7 × LWL + .3 × LOA) × Beam^1.33)
This is a ratio created by Ted Brewer as a measure of motion comfort. It provides a reasonable comparison between yachts of similar size and type. It is based on the fact that the faster the motion the more upsetting it is to the average person. Consider, though, that the typical summertime coastal cruiser will rarely encounter the wind and seas that an ocean going yacht will meet.
Numbers below 20 indicate a lightweight racing boat, small dinghy and such; 20 to 30 indicates a coastal cruiser; 30 to 40 indicates a moderate bluewater cruising boat; 40 to 50 indicates a heavy bluewater boat; over 50 indicates an extremely heavy bluewater boat.
Comfort ratio = Displacement ÷ (.65 × (.7 × LWL + .3 × LOA) × Beam^1.33)
This is a ratio created by Ted Brewer as a measure of motion comfort. It provides a reasonable comparison between yachts of similar size and type. It is based on the fact that the faster the motion the more upsetting it is to the average person. Consider, though, that the typical summertime coastal cruiser will rarely encounter the wind and seas that an ocean going yacht will meet.
Numbers below 20 indicate a lightweight racing boat, small dinghy and such; 20 to 30 indicates a coastal cruiser; 30 to 40 indicates a moderate bluewater cruising boat; 40 to 50 indicates a heavy bluewater boat; over 50 indicates an extremely heavy bluewater boat.
Capsize Screening Formula
CSF = Beam ÷ (Disp in cubic ft)^(1/3)
Designed to determine if a boat has blue water capability. The CSF compares beam with displacement since excess beam contributes to capsize and heavy displacement reduces capsize vulnerability. The boat is better suited for ocean passages (vs coastal cruising) if the result of the calculation is 2.0 or less. The lower the better.
CSF = Beam ÷ (Disp in cubic ft)^(1/3)
Designed to determine if a boat has blue water capability. The CSF compares beam with displacement since excess beam contributes to capsize and heavy displacement reduces capsize vulnerability. The boat is better suited for ocean passages (vs coastal cruising) if the result of the calculation is 2.0 or less. The lower the better.
S# Formula
S# = 3.972 × 10^(–(D/L)/526 + (0.691 × (log(SA/D) – 1)^0.8))
S# first appeared (that we know of) in TellTales, April 1988, “On a Scale of One to Ten” by A.P. Brooks. The equation incorporates SA/Disp (100% fore triangle) and Disp/length ratios to create a guide to probable boat performance vs. other boats of comparable size. For boats of the same length, generally the higher the S#, the lower the PHRF.
Under 2 – Slow, under powered; 2-3 – Cruiser; 3-5 – Racer Cruiser; 5+ – Fast/Racing
S# = 3.972 × 10^(–(D/L)/526 + (0.691 × (log(SA/D) – 1)^0.8))
S# first appeared (that we know of) in TellTales, April 1988, “On a Scale of One to Ten” by A.P. Brooks. The equation incorporates SA/Disp (100% fore triangle) and Disp/length ratios to create a guide to probable boat performance vs. other boats of comparable size. For boats of the same length, generally the higher the S#, the lower the PHRF.
Under 2 – Slow, under powered; 2-3 – Cruiser; 3-5 – Racer Cruiser; 5+ – Fast/Racing
Hull Speed Max Formula
HS = 1.34 × √LWL (in feet)
The maximum speed of a displacement hull (referring to a hull that travels through the water rather than on top of it, e.g. planing).
HS = 1.34 × √LWL (in feet)
The maximum speed of a displacement hull (referring to a hull that travels through the water rather than on top of it, e.g. planing).
Pounds per Inch Immersion Formula
PPI = LWL Area × 5.333
The weight required to sink the yacht one inch. Calculated by multiplying the LWL area by 5.333 for sea water or 5.2 for fresh water.
PPI = LWL Area × 5.333
The weight required to sink the yacht one inch. Calculated by multiplying the LWL area by 5.333 for sea water or 5.2 for fresh water.
| S.A. / Displacement | 35.79 |
| Ballast / Displacement, % | 74.45 |
| Displacement / Length (LWL) | 114.74 |
| Comfort Ratio | 9.25 |
| Capsize Screening Formula | 2.46 |
| S# | 6.48 |
| Hull Speed Max, knots | 5.69 |
| Pounds per Inch Immersion, lbs/inch | 454.80 |
Rig and Sail Particulars
S.A. Fore Formula
S.A. Fore = I * J / 2
This is the area of the fore triangle, calculated by multiplying I and J and dividing by 2.
S.A. Fore = I * J / 2
This is the area of the fore triangle, calculated by multiplying I and J and dividing by 2.
S.A. Main Formula
S.A. Main = P * E / 2
This is the area of the main triangle, calculated by multiplying P and E and dividing by 2.
S.A. Main = P * E / 2
This is the area of the main triangle, calculated by multiplying P and E and dividing by 2.
S.A. Total Formula
S.A. Total = S.A. Fore + S.A. Main
This is the sum of the fore and main sail areas.
S.A. Total = S.A. Fore + S.A. Main
This is the sum of the fore and main sail areas.
Forestay Length Formula
Est. Forestay Length = √(I² + J²)
This is the length of the forestay, calculated using the Pythagorean theorem.
Est. Forestay Length = √(I² + J²)
This is the length of the forestay, calculated using the Pythagorean theorem.
| I, m | 7.34 |
| J, m | 2.18 |
| P, m | 7.95 |
| E, m | 3.2 |
| S.A. Fore, ft²m² | 86.12 8 |
| S.A. Main, ft²m² | 136.92 12.72 |
| S.A. Total, ft²m² | 223.03 20.72 |
| Est. Forestay Length, ftm | 25.12 7.66 |
