Review of Vivacity 20

Vivacity 20.

Basic specs.

The Vivacity 20 is a small sailboat designed by the maritime architect Peter Stephenson in the mid sixties. Several hundred boats have been produced. The Vivacity 20 is built by the British yard Russell Marine Ltd..

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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.

Interior

The boat is equipped with 4 berths, a galley and toilet facility.
The headroom is below average

Rig

Rig of Vivacity 20.

The boat equipped with a masthead rig. The advantage of a masthead rig is its simplicity and the fact that a given sail area - compared with a fractional rig - can be carried lower and thus with less heeling moment.

Keel

The Vivacity 20 has been built with more than one type of keel.

One option is 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.

Another option is a bilge keel. A bilge keel is a double keel, which allows the boat to be beached. Bilge keels are the most popular keel for tidal waters.

The boat can enter even shallow marinas as the draft is just about 0.99 - 1.09 meter (3.25 - 3.55 ft) dependent on the load. See immersion rate below.

Engine

An outboard motor is often used on this boat. In that case Vivacity 20 will typically require a power of 2 - 3 hp, alternatively 40 - 48 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.

Trailer

Vivacity 20 on trailer. Launch of´Lido´ on Boskopdam, South Africa.

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 Vivacity 20 is 2.22, 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 Vivacity 20 is about 76 kg/cm, alternatively 425 lbs/inch.
Meaning: if you load 76 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 425 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 Vivacity 20 is 11.4 - 12.5.

Comparing this ratio with similar sailboats show that it is more comfortable than 50% of all similar sailboat designs. This is an average comfort value!

L/B (Length Beam Ratio)

What is L/B (Length Beam Ratio)?

The l/b ratio for Vivacity 20 is 2.86.

Compared with other similar sailboats it is slimmer than 69% of all other designs. It seems that the designer has chosen a slightly more speedy hull design.

Ballast Ratio

What is a Ballast Ratio?

The ballast ratio for Vivacity 20 is 39%.

This ballast ratio shows a righting moment that is higher than 58% 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 Vivacity 20 is 157 which categorizes this boat among 'light racers'.

66% 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 12m² (129 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**
Usage	Length		Diameter
Jib sheet	6.1 m	(20.0 feet)	8 mm	(5/16 inch)
Genoa sheet	6.1 m	(20.0 feet)	8 mm	(5/16 inch)
Mainsheet	15.2 m	(50.0 feet)	8 mm	(5/16 inch)
Spinnaker sheet	13.4 m	(44.0 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 Vivacity 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.