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Review of Impala 30


Impala 30
Impala 30.


Basic specs.

boat specifications
The Impala 30 is a sailboat designed by the Danish maritime architect E. Bjørn Jensen in the mid seventies. The Impala 30 is built by Otto H. Nielsen.

Looking for a new boat? Find a Impala 30 or similar boat for sale

Hull
Both the hull and the deck 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 hull is a double hull which improves the indoor climate. Especially when the water is colder than the air in the cabin, then the double hull insulates against cold water and reduce the condense water in the cabin.
The deck is a double deck which improves the indoor climate.

Interior
The interior is like many other boats made of mahogany.
The boat is equipped with 5-6 berths, 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
Impala 30 has more than one rig.

One option is 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.

Another option is 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 boat has a fin keel which means that it is more manoeuvrable but has less directional stability than a similar boat with a long keel. The keel is made of lead. Compared with iron, lead has the advantage of being 44% heavier, which allow a minor keel and hence less water resistance and higher speed. The boat can enter most marinas as the draft is just about 1.70 - 1.80 meter (5.58 - 5.88 ft) dependent on the load. See immersion rate below.

Engine
Impala 30 is typical equipped with an inboard Yanmar SB12G diesel engine at 12.0 hp (8 kW), which gives a max speed about 4.8 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.
The fuel tank which is made of stainless steel has a capacity of 30 liters (7 US gallons).

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 30 is 2.17, 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 6.9 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 30 is about 175 kg/cm, alternative 983 lbs/inch.
Meaning: if you load 175 kg cargo on the boat then it will sink 1 cm. Alternative, if you load 983 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 22,000 boat types and 350,000 data points.

Motion Comfort Ratio
What is Motion Comfort Ratio (MCR)?
The Motion Comfort Ratio for Impala 30 is 16.3 - 18.4.

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. A comfort value significantly below average.

L/B (Length Beam Ratio)
What is L/B (Length Beam Ratio)?
The l/b ratio for Impala 30 is 2.77.

Slim Wide 82% 0 50 100
Compared with other similar sailboats it is more spacy than 82% 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 30 is 42%.

Low High 58% 0 50 100
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 Impala 30 is 176 which categorizes this boat among 'light racers'.

Heavy Light 85% 0 50 100
85% 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 Impala 30 with ISO 8666 reference sail is 17.1, with a 135% genua the SA/D is 20.6.

Low High 62% 0 50 100
The SA/D ratio indicates that it is faster than 62% of all similar sailboat designs in light wind.

RSP (Relative Speed Performance)
What is Relative Speed Performance?
The Relative Speed Performance for Impala 30 is 82

Slow Fast 82% 0 50 100
The relative speed performance is 82 which means that a it is faster than 82% 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 30m2 (322 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 for fractional rig.
mainsail specifications genoa specifications spinnaker 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
Fractional rig
UsageLengthDiameter
Mainsail halyard 28.3 m(92.8 feet)10 mm(3/8 inch)
Jib/genoa halyard28.3 m(92.8 feet)10 mm(3/8 inch)
Spinnaker halyard28.3 m(92.8 feet)10 mm(3/8 inch)
Jib sheet 9.0 m(29.7 feet)12 mm(1/2 inch)
Genoa sheet9.0 m(29.7 feet)12 mm(1/2 inch)
Mainsheet 22.6 m(74.1 feet)12 mm(1/2 inch)
Spinnaker sheet19.9 m(65.2 feet)12 mm(1/2 inch)
Cunningham2.9 m(9.5 feet)10 mm(3/8 inch)
Kickingstrap5.8 m(19.0 feet)10 mm(3/8 inch)
Clew-outhaul5.8 m(19.0 feet)10 mm(3/8 inch)
Masthead rig
UsageLengthDiameter
Jib sheet 9.0 m(29.7 feet)12 mm(1/2 inch)
Genoa sheet9.0 m(29.7 feet)12 mm(1/2 inch)
Mainsheet 22.6 m(74.1 feet)12 mm(1/2 inch)
Spinnaker sheet19.9 m(65.2 feet)12 mm(1/2 inch)


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References