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Review of JOJ:20


JOJ:20
JOJ:20.

Basic specs.

sail specifications
The JOJ:20 is a small sailboat designed by the maritime architect Bertil Jonson in the late seventies.

Looking for a new boat? Find a JOJ:20 or similar boat for sale

Interior
The interior is like many other boats made of mahogany.
The boat is equipped with 4 berths and a galley.
Note: the boat has also been sold to be self-made/-interiored, which means that the quality of each boat may vary.

Keel
Keel
Keel of JOJ:20.

JOJ:20 can enter even shallow marinas as the draft is just about 1.15 - 1.25 meter (3.77 - 4.07 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.

Stability and Safety

What is Capsize Screening Formula (CSF)?

The capsize screening value for JOJ:20 is 2.48, indicating that this boat would not be accepted to participate in ocean races.


Immersion rate

The immersion rate is defined as the weight required to sink the boat a certain level. The immersion rate for JOJ:20 is about 91 kg/cm, alternatively 514 lbs/inch.
Meaning: if you load 91 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 514 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.

L/B (Length Beam Ratio)

What is L/B (Length Beam Ratio)?

The l/b ratio for JOJ:20 is 2.59.

Slim Wide 62% 0 50 100
Compared with other similar sailboats it is more spacy than 62% of all other designs. It seems that the designer has chosen a slightly more spacy hull design.


SA/D (Sail Area Displacement ratio)

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): 18.57


Maintenance

Rig

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.



Guiding dimensions of running rig
UsageLengthDiameter
Jib sheet 6.0 m(19.6 feet)8 mm(5/16 inch)
Genoa sheet6.0 m(19.6 feet)8 mm(5/16 inch)
Mainsheet 14.9 m(48.9 feet)8 mm(5/16 inch)
Spinnaker sheet13.1 m(43.0 feet)8 mm(5/16 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 JoJ:20 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