Jon 33 anno 1980. Bella Vita i Utklippans hamn

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Rig

The boat 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.

Keel

The keel is made of lead. Compared with iron, lead has the advantage of being 44% heavier, which allows a smaller keel and hence less water resistance and higher speed.

The boat can only enter major marinas as the draft is about 1.85 - 1.95 meter (6.07 - 6.37 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.

Stability and Safety

What is Capsize Screening Formula (CSF)?

The capsize screening value for Jon 33 is 1.85, indicating that this boat could - if evaluated by this formula alone - be accepted to participate in ocean races.

Theoretical Maximum Hull Speed

What is Theoretical Maximum Hull Speed?

The theoretical maximal speed of a displacement boat of this length is 6.9 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.

Immersion rate

The immersion rate is defined as the weight required to sink the boat a certain level.
The immersion rate for Jon 33 is about 181 kg/cm, alternatively 1015 lbs/inch.

Meaning: if you load 181 kg cargo on the boat then it will sink 1 cm.
Alternatively, if you load 1015 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.

Motion Comfort Ratio

What is Motion Comfort Ratio (MCR)?

The Motion Comfort Ratio for Jon 33 is 29.3.

L/B (Length Beam Ratio)

What is L/B (Length Beam Ratio)?

The l/b ratio for Jon 33 is 3.01.

Ballast Ratio

The ballast ratio for Jon 33 is 41%.

D/L (Displacement Length Ratio)

What is Displacement Length Ratio?

The DL-ratio for Jon 33 is 314 which categorizes this boat among 'medium weight cruisers'.

SA/D (Sail Area Displacement ratio)

What is SA/D (Sail Area Displacement ratio)?

The SA/D for Jon 33 with ISO 8666 reference sail is 14.6, with a 135% genua the SA/D is 17.6.

Over- / underrigged

RSP (Relative Speed Performance)

What is Relative Speed Performance?

The Relative Speed Performance for Jon 33 is 54

Bottom Paint

When buying anti-fouling bottom paint, it's nice to know how much to buy.
The surface of the wet bottom is about 32m^{2} (344 ft^{2}).

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.

Rig

Dimensions of sail for masthead rig.

Are your sails worn out? You might find your next sail here: Sails for Sale

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 | ||

Mainsail halyard | 31.3 m | (102.7 feet) | 10 mm | (3/8 inch) |

Jib/genoa halyard | 31.3 m | (102.7 feet) | 10 mm | (3/8 inch) |

Spinnaker halyard | 31.3 m | (102.7 feet) | 10 mm | (3/8 inch) |

Jib sheet | 10.1 m | (33.0 feet) | 12 mm | (1/2 inch) |

Genoa sheet | 10.1 m | (33.0 feet) | 12 mm | (1/2 inch) |

Mainsheet | 25.2 m | (82.6 feet) | 12 mm | (1/2 inch) |

Spinnaker sheet | 22.2 m | (72.7 feet) | 12 mm | (1/2 inch) |

Cunningham | 3.4 m | (11.0 feet) | 10 mm | (3/8 inch) |

Kickingstrap | 6.7 m | (22.0 feet) | 10 mm | (3/8 inch) |

Clew-outhaul | 6.7 m | (22.0 feet) | 10 mm | (3/8 inch) |

Boat owner's ideas

This section shown boat owner's changes, improvements, etc. Here you might find inspiration for your boat.

Do you have changes/improvements you would like to share? Upload a photo and describe what to look for.

Finally

We are always looking for new photos. If you can contribute with photos for Jon 33 it would be a great help.

If you have any comments to the review, improvement suggestions, or the like, feel free to contact us. Criticism helps us to improve.

References