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Review of Impala 20


Impala 20
Impala 20.


Basic specs.

sail specifications
The Impala 20 is a small sailboat designed by the Danish maritime architect E. Bjørn Jensen in the late seventies.

Looking for a new boat? Find an Impala 20 or similar boat for sale

Hull

The hull is made of plywood.


Interior

The boat is equipped with a galley and toilet facility.

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


Rig

The Impala 20 is 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

Fin keel

The Impala 20 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.

Impala 20 can enter even shallow marinas as the draft is just about 1.20 - 1.30 meter (3.94 - 4.24 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 Impala 20 is 2.72, 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 Impala 20 is about 95 kg/cm, alternatively 536 lbs/inch.
Meaning: if you load 95 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 536 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 Impala 20 is 10.1.

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 Impala 20 is 2.31.

Slim Wide 90% 0 50 100
Compared with other similar sailboats it is more spacy than 90% of all other designs. It seems that the designer has chosen a significantly more spacy hull design.


Ballast Ratio

What is a Ballast Ratio?

The ballast ratio for Impala 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 Impala 20 is 187 which categorizes this boat among 'light racers'.

Heavy Light 50% 0 50 100
50% of all similar sailboat designs are categorized as heavier. This boat has a precise average ratio between displacement and length!


RSP (Relative Speed Performance)

What is Relative Speed Performance?

The Relative Speed Performance for Impala 20 is 88

Slow Fast 88% 0 50 100
The relative speed performance is 88 which means that a it is faster than 88% 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 16m2 (172 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 6.2 m(20.5 feet)10 mm(3/8 inch)
Genoa sheet6.2 m(20.5 feet)10 mm(3/8 inch)
Mainsheet 15.6 m(51.3 feet)10 mm(3/8 inch)
Spinnaker sheet13.8 m(45.1 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 Impala 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