Review of Fifty 21
Basic specs.
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The hull is made of fibreglass. Generally, a hull made of fibreglass requires only a minimum of maintenance during the sailing season. And outside the sailing season, just bottom cleaning and perhaps anti-fouling painting once a year - a few hours of work, that's all.
The boat is equipped with 4 berths.
The Fifty 21 is equipped with a masthead rig. The advantage of a masthead rig is its simplicity and the fact that a given sail area - compared with a fractional rig - can be carried lower and thus with less heeling moment.
The boat may be equipped with a diesel engine at 12 hp (8 kW). Calculated max speed is about 5.3 knots.
Sailing characteristics
This section covers widely used rules of thumb to describe the sailing characteristics. Please note that even though the calculations are correct, the interpretation of the results might not be valid for extreme boats.
What is Capsize Screening Formula (CSF)?
The capsize screening value for Fifty 21 is 2.03, indicating that this boat would not be accepted to participate in ocean races.
What is Theoretical Maximum Hull Speed?
The theoretical maximal speed of a displacement boat of this length is 5.5 knots. The term "Theoretical Maximum Hull Speed" is widely used even though a boat can sail faster. The term shall be interpreted as above the theoretical speed a great additional power is necessary for a small gain in speed.
The immersion rate is defined as the weight required to sink the boat a certain level.
The immersion rate for Fifty 21 is about 84 kg/cm, alternatively 473 lbs/inch.
Meaning: if you load 84 kg cargo on the boat then it will sink 1 cm.
Alternatively, if you load 473 lbs cargo on the boat it will sink 1 inch.
Sailing statistics
This section is statistical comparison with similar boats of the same category. The basis of the following statistical computations is our unique database with more than 26,000 different boat types and 350,000 data points.
What is Motion Comfort Ratio (MCR)?
The Motion Comfort Ratio for Fifty 21 is 21.1.
What is L/B (Length Beam Ratio)?
The l/b ratio for Fifty 21 is 2.55.
What is Displacement Length Ratio?
The DL-ratio for Fifty 21 is 367 which categorizes this boat among 'heavy cruisers'.
SA/D (Sail Area Displacement ratio)
Indicates how fast the boat is in light wind:
- Cruising Boats have ratios 10-15
- Cruiser-Racers have ratios 16-20
- Racers have ratios above 20
- High-Performance Racers have ratios above 24
Sail-area/displacement ratio (SA/D ratio): 12.71
Maintenance
If you need to renew parts of your running rig and is not quite sure of the dimensions, you may find the estimates computed below useful.
| Usage | Length | Diameter | ||
| Jib sheet | 6.2 m | (20.5 feet) | 10 mm | (3/8 inch) |
| Genoa sheet | 6.2 m | (20.5 feet) | 10 mm | (3/8 inch) |
| Mainsheet | 15.6 m | (51.3 feet) | 10 mm | (3/8 inch) |
| Spinnaker sheet | 13.8 m | (45.1 feet) | 10 mm | (3/8 inch) |
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