Review of Biraou 4,70
Basic specs.
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The boat can enter even shallow marinas as the draft is just about 0.66 - 0.76 meter (2.17 - 2.47 ft) dependent on the load. See immersion rate below.
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 Biraou 4,70 is 3.28, 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 5.1 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 Biraou 4,70 is about 45 kg/cm, alternatively 254 lbs/inch.
Meaning: if you load 45 kg cargo on the boat then it will sink 1 cm.
Alternatively, if you load 254 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 Biraou 4,70 is 2.7.
What is L/B (Length Beam Ratio)?
The l/b ratio for Biraou 4,70 is 3.07.
What is Displacement Length Ratio?
The DL-ratio for Biraou 4,70 is 30 which categorizes this boat among 'ultra light racers'.
Maintenance
When buying anti-fouling bottom paint, it's nice to know how much to buy.
The surface of the wet bottom is about 7m2 (75 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 | 4.6 m | (15.2 feet) | 8 mm | (5/16 inch) |
| Genoa sheet | 4.6 m | (15.2 feet) | 8 mm | (5/16 inch) |
| Mainsheet | 11.6 m | (38.1 feet) | 8 mm | (5/16 inch) |
| Spinnaker sheet | 10.2 m | (33.5 feet) | 8 mm | (5/16 inch) |
This section shown boat owner's changes, improvements, etc. Here you might find inspiration for your boat.
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