The keel is made of iron. Many people prefer lead keel in favour of iron. The main argument is that lead is much heavier than iron and a lead keel can therefore be made smaller which again result in less wet surface, i.e. less drag. In fact iron is quite heavy, just 30% less heavy than lead, so the advantage of a lead keel is often overstated.
The boat can enter even shallow marinas as the draft is just about 0.65 - 0.75 meter (2.13 - 2.43 ft) dependent on the load. See immersion rate below.
An outboard motor is often used on this boat. In that case First Class 7 will typically require a power of 2 - 3 hp, alternatively 35 - 42 lbs thrust if you prefer an electrical motor. Electric outboards are becoming popular for sailboat owners who want clean instant power with less noise and no exhaust fumes.
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 First Class 7 is 2.66, indicating that this boat would not be accepted to participate in ocean races.
The immersion rate is defined as the weight required to sink the boat a certain level.
The immersion rate for First Class 7 is about 116 kg/cm, alternatively 652 lbs/inch.
Meaning: if you load 116 kg cargo on the boat then it will sink 1 cm.
Alternatively, if you load 652 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 L/B (Length Beam Ratio)?
The l/b ratio for First Class 7 is 2.90.
The ballast ratio for First Class 7 is 33%.
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): 29.49
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 | 7.1 m | (23.3 feet) | 10 mm | (3/8 inch) |
Genoa sheet | 7.1 m | (23.3 feet) | 10 mm | (3/8 inch) |
Mainsheet | 17.8 m | (58.2 feet) | 10 mm | (3/8 inch) |
Spinnaker sheet | 15.6 m | (51.2 feet) | 10 mm | (3/8 inch) |
This section shown boat owner's changes, improvements, etc. Here you might find inspiration for your boat.
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