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Review of Ajax 23


Basic specs.

sail specifications
The Ajax 23 is a small sailboat designed by the maritime architect Oliver J. Lee in the mid sixties. Less than 100 boats have been produced. The Ajax 23 is built by the British yard Halmatic.

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Hull

The hull is made of fibreglass. Generally, a hull made of fibreglass requires only a minimum of maintenance during the sailing season. And outside the sailing season, just bottom cleaning and perhaps anti-fouling painting once a year - a few hours of work, that's all.


Keel

The Ajax 23 is equipped with a fin keel. The fin keel is the most common keel and provides splendid manoeuvrability. The downside is that it has less directional stability than a long keel.

The boat can enter even shallow marinas as the draft is just about 1.12 - 1.22 meter (3.67 - 3.97 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 Ajax 23 is 2.08, 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 Ajax 23 is about 76 kg/cm, alternatively 429 lbs/inch.
Meaning: if you load 76 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 429 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 Ajax 23 is 12.0.

Low High 24% 0 50 100
Comparing this ratio with similar sailboats show that it is more comfortable than 24% of all similar sailboat designs. This is a comfort value significantly below average.


L/B (Length Beam Ratio)

What is L/B (Length Beam Ratio)?

The l/b ratio for Ajax 23 is 3.62.

Wide Slim 99% 0 50 100
Compared with other similar sailboats it is slimmer than 99% of all other designs. It seems that the designer has chosen a significantly more speedy hull design. This type of design is also referred to as 'needle'.


D/L (Displacement Length Ratio)

What is Displacement Length Ratio?

The DL-ratio for Ajax 23 is 120 which categorizes this boat among 'ultra light racers'.

Heavy Light 86% 0 50 100
86% of all similar sailboat designs are categorized as heavier. A light displacement requires less sailarea and has higher accellerations.


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 13m2 (139 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

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 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 17.7 m(58.2 feet)10 mm(3/8 inch)
Spinnaker sheet15.6 m(51.2 feet)10 mm(3/8 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 Ajax 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