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.
Fin keel
The Alerion Express 20 is equipped with a fin keel. The fin keel is the most common keel and provides splendid manoeuvrability. The downside is that it has less directional stability than a long keel.
The boat can enter even shallow marinas as the draft is just about 1.07 - 1.17 meter (3.51 - 3.81 ft) dependent on the load. See immersion rate below.
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 Alerion Express 20 is 2.20, 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 Alerion Express 20 is about 72 kg/cm, alternatively 406 lbs/inch.
Meaning: if you load 72 kg cargo on the boat then it will sink 1 cm.
Alternatively, if you load 406 lbs cargo on the boat it will sink 1 inch.
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 Alerion Express 20 is 12.6.
What is L/B (Length Beam Ratio)?
The l/b ratio for Alerion Express 20 is 2.93.
The ballast ratio for Alerion Express 20 is 41%.
What is Displacement Length Ratio?
The DL-ratio for Alerion Express 20 is 169 which categorizes this boat among 'light racers'.
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): 22.84
When buying anti-fouling bottom paint, it's nice to know how much to buy.
The surface of the wet bottom is about 12m2 (129 ft2).
Based on this, your favourite maritime shop can tell you the quantity you need.
Note: If you use a paint roller you will need more paint than if you use a paintbrush.
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 | 6.1 m | (20.0 feet) | 8 mm | (5/16 inch) |
Genoa sheet | 6.1 m | (20.0 feet) | 8 mm | (5/16 inch) |
Mainsheet | 15.2 m | (50.0 feet) | 8 mm | (5/16 inch) |
Spinnaker sheet | 13.4 m | (44.0 feet) | 8 mm | (5/16 inch) |
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