Review of Macintosh 47

Basic specs.

The Macintosh 47 is a large sailboat designed by the maritime architect Tim Kings in the early nineties. Only a few boats have been produced. The Macintosh 47 is built by Hansen Marine.

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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.

Interior

The boat is equipped with 946.0 liter fresh water capacity.

Keel

Fin keel

The Macintosh 47 is equipped with a fin keel. A boat with a fin keel is more manoeuvrable but has less directional stability than a similar boat with a full keel.

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 enter most marinas as the draft is just about 1.73 - 1.83 meter (5.68 - 5.98 ft) dependent on the load. See immersion rate below.

Engine

Macintosh 47 is typically equipped with an inboard Yanmar 4JH-DTBE diesel engine at 77 hp (57 kW). Calculated max speed is about 7.5 knots

The fuel tank has a capacity of 416.0 liters (109 US gallons, 91 imperial 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 Macintosh 47 is 1.84, 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 8.5 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 Macintosh 47 is about 356 kg/cm, alternatively 1998 lbs/inch.
Meaning: if you load 356 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 1998 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 Macintosh 47 is 32.0.

Comparing this ratio with similar sailboats show that it is more comfortable than 42% 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 Macintosh 47 is 3.29.

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

Ballast Ratio

What is a Ballast Ratio?

The ballast ratio for Macintosh 47 is 41%.

This ballast ratio shows a righting moment that is higher than 76% of all similar sailboat designs. A righting moment (ability to resist heeling) significantly above average.

D/L (Displacement Length Ratio)

What is Displacement Length Ratio?

The DL-ratio for Macintosh 47 is 212 which categorizes this boat among 'light crusers & offshore racers'.

58% 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 Macintosh 47 with ISO 8666 reference sail is 17.4, with a 135% genua the SA/D is 21.0.

The SA/D ratio indicates that it is faster than 27% of all similar sailboat designs in light wind.

Over- / underrigged

The Macintosh 47 has more rig than 50% of all similar sailboats, which indicates that this rig is spot on average!

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 56m² (602 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	40.9 m	(134.3 feet)	14 mm	(0.55 inch)
Jib/genoa halyard	40.9 m	(134.3 feet)	14 mm	(0.55 inch)
Spinnaker halyard	40.9 m	(134.3 feet)	14 mm	(0.55 inch)
Jib sheet	14.4 m	(47.2 feet)	16 mm	(5/8 inch)
Genoa sheet	14.4 m	(47.2 feet)	16 mm	(5/8 inch)
Mainsheet	36.0 m	(117.9 feet)	16 mm	(5/8 inch)
Spinnaker sheet	31.6 m	(103.8 feet)	16 mm	(5/8 inch)
Cunningham	5.2 m	(17.0 feet)	14 mm	(0.55 inch)
Kickingstrap	10.4 m	(34.0 feet)	14 mm	(0.55 inch)
Clew-outhaul	10.4 m	(34.0 feet)	14 mm	(0.55 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 Macintosh 47 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.