YachtDatabase.com

Review of Johnson 23


Basic specs.

sail specifications
The Johnson 23 is a small sailboat designed by the Swedish maritime architect Bo Johnson in the late seventies. A few hundred boats have been produced. The Johnson 23 is built by the Swedish yard Johnson båtar AB.

Here we would have liked to show you nice photos of the Johnson 23.
If you have a photo you would like to share: Upload Image

Looking for a new boat? Find a Johnson 23 or similar boat for sale

Interior

The boat is equipped with 4 berths.

Note: the boat has also been sold to be self-made/-interiored, which means that the quality of each boat may vary.


Rig

The Johnson 23 is equipped with a fractional rig. A fractional rig has smaller headsails which make tacking easier, which is an advantage for cruisers and racers, of course. The downside is that having the wind from behind often requires a gennaker or a spinnaker for optimal speed.


Keel

Unknown keel type

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.

Johnson 23 can enter even shallow marinas as the draft is just about 1.40 - 1.50 meter (4.59 - 4.89 ft) dependent on the load. See immersion rate below.


Engine

An outboard motor is often used on this boat. In that case the boat will typically require a power of 2 - 3 hp, alternatively 48 - 58 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.


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 Johnson 23 is 2.44, indicating that this boat would not 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 5.9 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 Johnson 23 is about 98 kg/cm, alternatively 553 lbs/inch.
Meaning: if you load 98 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 553 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.

Motion Comfort Ratio

What is Motion Comfort Ratio (MCR)?

The Motion Comfort Ratio for Johnson 23 is 11.2.

Low High 27% 0 50 100
Comparing this ratio with similar sailboats show that it is more comfortable than 27% of all similar sailboat designs. This comfort value is just below average.


L/B (Length Beam Ratio)

What is L/B (Length Beam Ratio)?

The l/b ratio for Johnson 23 is 2.67.

Slim Wide 69% 0 50 100
Compared with other similar sailboats it is more spacy than 69% of all other designs. It seems that the designer has chosen a slightly more spacy hull design.


Ballast Ratio

What is a Ballast Ratio?

The ballast ratio for Johnson 23 is 58%.

Low High 98% 0 50 100
This ballast ratio shows a righting moment that is higher than 98% of all similar sailboat designs. A righting moment (ability to resist heeling) significantly above average.


D/L (Displacement Length Ratio)

What is Displacement Length Ratio?

The DL-ratio for Johnson 23 is 149 which categorizes this boat among 'ultra light racers'.

Heavy Light 73% 0 50 100
73% of all similar sailboat designs are categorized as heavier. A light displacement requires less sailarea and has higher accellerations.


SA/D (Sail Area Displacement ratio)

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

The SA/D for Johnson 23 with ISO 8666 reference sail is 16.9, with a 135% genua the SA/D is 19.7.

Low High 42% 0 50 100
The SA/D ratio indicates that it is faster than 42% of all similar sailboat designs in light wind.


Over- / underrigged

Low High 21% 0 50 100
The Johnson 23 has more rig than 21% of all similar sailboats, which indicates that the boat is significantly underrigged.


RSP (Relative Speed Performance)

What is Relative Speed Performance?

The Relative Speed Performance for Johnson 23 is 62

Slow Fast 62% 0 50 100
The relative speed performance is 62 which means that a it is faster than 62% of all similar sailboat designs.


Maintenance

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 17m2 (182 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.


Rig

Dimensions of sail for fractional rig.

mainsail specifications genoa specifications spinnaker specifications

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.



Guiding dimensions of running rig
UsageLengthDiameter
Mainsail halyard 20.4 m(67.1 feet)8 mm(5/16 inch)
Jib/genoa halyard20.4 m(67.1 feet)8 mm(5/16 inch)
Spinnaker halyard20.4 m(67.1 feet)8 mm(5/16 inch)
Jib sheet 6.7 m(21.9 feet)10 mm(3/8 inch)
Genoa sheet6.7 m(21.9 feet)10 mm(3/8 inch)
Mainsheet 16.7 m(54.8 feet)10 mm(3/8 inch)
Spinnaker sheet14.7 m(48.2 feet)10 mm(3/8 inch)
Cunningham2.4 m(7.9 feet)8 mm(5/16 inch)
Kickingstrap4.8 m(15.7 feet)8 mm(5/16 inch)
Clew-outhaul4.8 m(15.7 feet)8 mm(5/16 inch)

Boat owner's ideas

This section is reserved boat owner's modifications, improvements, etc. Here you might find (or contribute with) inspiration for your boat.

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



Finally

We are always looking for new photos. If you can contribute with photos for Johnson 23 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