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Review of Impala 28


Impala 28
Impala 28.

Basic specs.

sail specifications
The Impala 28 is a sailboat designed by the Danish maritime architect E. Bjørn Jensen in the early seventies. Less than 100 boats have been produced.

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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 interior is like most other boats made of teak.
The boat is equipped with 2 cabins, 5 berths, a galley and toilet facility.

Rig
Rig
Rig of Impala 28 anno 1973.
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.

Keel

The Impala 28 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 most marinas as the draft is just about 1.50 - 1.60 meter (4.92 - 5.22 ft) dependent on the load. See immersion rate below.


Engine

Impala 28 is typically equipped with an inboard Bukh diesel engine at 10.0 hp (7 kW), which gives a max speed about 4.1 knots.

The transmission is a shaft drive. A shaft drive will in the long run require less maintenence than other types of drive e.g. a sail drive.


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 28 is 1.87, indicating that this boat could - if evaluated by this formula alone - 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 6.1 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 28 is about 117 kg/cm, alternatively 655 lbs/inch.
Meaning: if you load 117 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 655 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 28 is 25.2.

Low High 69% 0 50 100
Comparing this ratio with similar sailboats show that it is more comfortable than 69% of all similar sailboat designs. This comfort value is just above average.


L/B (Length Beam Ratio)

What is L/B (Length Beam Ratio)?

The l/b ratio for Impala 28 is 3.16.

Wide Slim 62% 0 50 100
Compared with other similar sailboats it is slimmer than 62% 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 Impala 28 is 340 which categorizes this boat among 'heavy cruisers'.

Heavy Light 14% 0 50 100
14% of all similar sailboat designs are categorized as heavier. A heavy displacement combined with smaller water plane area has lower acceleration and is more comfortable.


RSP (Relative Speed Performance)

What is Relative Speed Performance?

The Relative Speed Performance for Impala 28 is 27

Slow Fast 27% 0 50 100
The relative speed performance is 27 which means that a it is faster than 27% 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 20m2 (215 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 8.6 m(28.3 feet)10 mm(3/8 inch)
Genoa sheet8.6 m(28.3 feet)10 mm(3/8 inch)
Mainsheet 21.5 m(70.7 feet)10 mm(3/8 inch)
Spinnaker sheet19.0 m(62.2 feet)10 mm(3/8 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 Impala 28 (Jensen) 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