Review of O'Day 20

Basic specs.

The O'Day 20 is a small sailboat designed by the American maritime architect bureau C Raymond Hunt Associates, Inc. in the early seventies. Several hundred boats have been produced. The O'Day 20 is built by the American yard O'Day Corp..

Here we would have liked to show you nice photos of the O'Day 20.
If you have a photo you would like to share: Upload Image

Looking for a new boat? Find a O'Day 20 or similar boat for sale

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 O'Day 20 is equipped with a centerboard keel. A centerboard keel is a pivoting lifting keel, allowing to sail both coastal and inland waters.

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 sail close to the beach as the draft is just 0.34 - 0.44 meter (1.12 - 1.42 ft) dependent of 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 1 - 2 hp, alternatively 32 - 38 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 O'Day 20 is 2.39, 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 O'Day 20 is about 75 kg/cm, alternatively 421 lbs/inch.
Meaning: if you load 75 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 421 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 O'Day 20 is 10.3.

Comparing this ratio with similar sailboats show that it is more comfortable than 34% 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 O'Day 20 is 2.80.

Compared with other similar sailboats it is slimmer than 66% of all other designs. It seems that the designer has chosen a slightly more speedy hull design.

D/L (Displacement Length Ratio)

What is Displacement Length Ratio?

The DL-ratio for O'Day 20 is 138 which categorizes this boat among 'ultra light racers'.

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 O'Day 20 with ISO 8666 reference sail is 20.5, with a 135% genua the SA/D is 24.3.

The SA/D ratio indicates that it is faster than 69% of all similar sailboat designs in light wind.

Over- / underrigged

The O'Day 20 has more rig than 96% of all similar sailboats, which indicates that the boat is significantly overrigged.

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 14m² (150 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.

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**
Usage	Length		Diameter
Mainsail halyard	16.9 m	(55.5 feet)	6 mm	(1/4 inch)
Jib/genoa halyard	16.9 m	(55.5 feet)	6 mm	(1/4 inch)
Spinnaker halyard	16.9 m	(55.5 feet)	6 mm	(1/4 inch)
Jib sheet	6.0 m	(19.6 feet)	8 mm	(5/16 inch)
Genoa sheet	6.0 m	(19.6 feet)	8 mm	(5/16 inch)
Mainsheet	14.9 m	(49.0 feet)	8 mm	(5/16 inch)
Spinnaker sheet	13.1 m	(43.1 feet)	8 mm	(5/16 inch)
Cunningham	2.4 m	(8.0 feet)	6 mm	(1/4 inch)
Kickingstrap	4.9 m	(16.0 feet)	6 mm	(1/4 inch)
Clew-outhaul	4.9 m	(16.0 feet)	6 mm	(1/4 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 O'Day 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

[Ref 1]: ISO 8666 Small craft — Principal data.
[Ref 3]: ISO 12215-5 Small craft — Hull construction and scantlings.