Review of Antrim 20

Basic specs.

sail specifications
The Antrim 20 is a small sailboat designed by the American maritime architect Jim Antrim in the early eighties.

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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.


The boat 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 genaker or a spinnaker for optimal speed.


The Antrim 20 is equipped with a fin keel. A boat with a fin keel is more manoeuvrable but has less directional stability than a similar boat with a long keel.

The boat can enter even shallow marinas as the draft is just about 1.22 - 1.32 meter (4.00 - 4.30 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 Antrim 20 is 2.61, 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 5.6 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 Antrim 20 is about 87 kg/cm, alternatively 487 lbs/inch.
Meaning: if you load 87 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 487 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 Antrim 20 is 9.7.

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 Antrim 20 is 2.55.

Slim Wide 73% 0 50 100
Compared with other similar sailboats it is more spacy than 73% 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 Antrim 20 is 40%.

Low High 62% 0 50 100
This ballast ratio shows a righting moment that is higher than 62% of all similar sailboat designs. A righting moment (ability to resist heeling) just above average.

D/L (Displacement Length Ratio)

What is Displacement Length Ratio?

The DL-ratio for Antrim 20 is 154 which categorizes this boat among 'light racers'.

Heavy Light 66% 0 50 100
66% 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 Antrim 20 with ISO 8666 reference sail is 23.9, with a 135% genua the SA/D is 27.4.

Low High 90% 0 50 100
The SA/D ratio indicates that it is faster than 90% of all similar sailboat designs in light wind.

Over- / underrigged

Low High 88% 0 50 100
The Antrim 20 has more rig than 88% of all similar sailboats, which indicates that the boat is significantly overrigged.


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 15m2 (161 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.


Dimensions of sail for fractional rig.

mainsail specifications headsail 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
Mainsail halyard 21.5 m(70.5 feet)8 mm(5/16 inch)
Jib/genoa halyard21.5 m(70.5 feet)8 mm(5/16 inch)
Spinnaker halyard21.5 m(70.5 feet)8 mm(5/16 inch)
Jib sheet 6.2 m(20.4 feet)10 mm(3/8 inch)
Genoa sheet6.2 m(20.4 feet)10 mm(3/8 inch)
Mainsheet 15.5 m(51.0 feet)10 mm(3/8 inch)
Spinnaker sheet13.7 m(44.9 feet)10 mm(3/8 inch)
Cunningham3.0 m(10.0 feet)8 mm(5/16 inch)
Kickingstrap6.1 m(20.0 feet)8 mm(5/16 inch)
Clew-outhaul6.1 m(20.0 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.

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