Review of Marlow-Hunter 31

Basic specs.

The Marlow-Hunter 31 is a sailboat designed by the maritime architect Glenn Henderson in the mid 2010.

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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 189.0 liter fresh water capacity.

Keel

Fin keel

The Marlow-Hunter 31 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 1.65 - 1.75 meter (5.41 - 5.71 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 Marlow-Hunter 31 is 2.08, 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 7.3 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 Marlow-Hunter 31 is about 218 kg/cm, alternatively 1224 lbs/inch.
Meaning: if you load 218 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 1224 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 Marlow-Hunter 31 is 22.2.

Comparing this ratio with similar sailboats show that it is more comfortable than 38% 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 Marlow-Hunter 31 is 2.73.

Compared with other similar sailboats it is more spacy than 86% 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 Marlow-Hunter 31 is 28%.

This ballast ratio shows a righting moment that is higher than 4% of all similar sailboat designs. A righting moment (ability to resist heeling) significantly below average.

D/L (Displacement Length Ratio)

What is Displacement Length Ratio?

The DL-ratio for Marlow-Hunter 31 is 202 which categorizes this boat among 'light crusers & offshore racers'.

69% 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 Marlow-Hunter 31 with ISO 8666 reference sail is 8.2, with a 135% genua the SA/D is 10.4.

The SA/D ratio indicates that it is faster than 1% of all similar sailboat designs in light wind.

Over- / underrigged

The Marlow-Hunter 31 has more rig than 15% of all similar sailboats, which indicates that the boat is significantly underrigged.

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 36m² (387 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	4.1 m	(13.4 feet)	10 mm	(3/8 inch)
Jib/genoa halyard	4.1 m	(13.4 feet)	10 mm	(3/8 inch)
Spinnaker halyard	4.1 m	(13.4 feet)	10 mm	(3/8 inch)
Jib sheet	9.9 m	(32.3 feet)	12 mm	(1/2 inch)
Genoa sheet	9.9 m	(32.3 feet)	12 mm	(1/2 inch)
Mainsheet	24.6 m	(80.9 feet)	12 mm	(1/2 inch)
Spinnaker sheet	21.7 m	(71.2 feet)	12 mm	(1/2 inch)
Cunningham	11.1 m	(36.5 feet)	10 mm	(3/8 inch)
Kickingstrap	22.2 m	(72.9 feet)	10 mm	(3/8 inch)
Clew-outhaul	22.2 m	(72.9 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 Marlow-Hunter 31 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.