Review of Johnson 30
Basic specs.
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The boat is equipped with 4 berths and a galley.
The Johnson 30 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 Johnson 30 has been equipped with different engine alternatives.
Alternative 1:
The boat may be equipped with an inboard Volvo Penta MD 3B diesel engine at 36 hp (26 kW).
The transmission is a shaft drive. A shaft drive will in the long run require less maintenance than other types of drive e.g. a sail drive.
Alternative 2:
Johnson 30 may be equipped with an inboard Volvo Penta MD 21 diesel engine at 60 hp (44 kW). Max speed is 7.0 knots.
The transmission is a shaft drive. A shaft drive will in the long run require less maintenance than other types of drive e.g. a sail drive.
Alternative 3:
The boat may be equipped with an inboard Ford diesel engine at 80 hp (59 kW). Max speed is 9.0 knots.
The transmission is a shaft drive. A shaft drive will in the long run require less maintenance than other types of drive e.g. a sail drive.
The fuel tank has a capacity of 300.0 liters (79 US gallons, 65 imperial gallons).
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 Johnson 30 is 1.86, indicating that this boat could - if evaluated by this formula alone - 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 Johnson 30 is about 194 kg/cm, alternatively 1087 lbs/inch.
Meaning: if you load 194 kg cargo on the boat then it will sink 1 cm.
Alternatively, if you load 1087 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 L/B (Length Beam Ratio)?
The l/b ratio for Johnson 30 is 2.92.
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 | 9.2 m | (30.2 feet) | 12 mm | (1/2 inch) |
| Genoa sheet | 9.2 m | (30.2 feet) | 12 mm | (1/2 inch) |
| Mainsheet | 23.0 m | (75.5 feet) | 12 mm | (1/2 inch) |
| Spinnaker sheet | 20.2 m | (66.4 feet) | 12 mm | (1/2 inch) |
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