Review of Contest 31 HT

Basic specs.

The Contest 31 HT is a sailboat designed by the Dutch maritime architect Dick Zaal in the early seventies. A few hundred boats have been produced. The Contest 31 HT is built by the Dutch yard Conyplex N.V..

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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 5/6 berths.
The headroom is above average

Rig

The boat 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

The Contest 31 HT 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 long keel.

The boat can enter most marinas as the draft is just about 1.75 - 1.85 meter (5.74 - 6.04 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.

Theoretical Maximum Hull Speed

What is Theoretical Maximum Hull Speed?

The theoretical maximal speed of a displacement boat of this length is 6.7 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 Contest 31 HT is about 162 kg/cm, alternatively 912 lbs/inch.
Meaning: if you load 162 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 912 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.

L/B (Length Beam Ratio)

What is L/B (Length Beam Ratio)?

The l/b ratio for Contest 31 HT is 3.02.

Compared with other similar sailboats it is more spacy than 62% 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 Contest 31 HT is 47%.

This ballast ratio shows a righting moment that is higher than 82% of all similar sailboat designs. A righting moment (ability to resist heeling) significantly above average.

Over- / underrigged

The Contest 31 HT 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 28m² (301 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 masthead rig.

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	27.4 m	(90.0 feet)	10 mm	(3/8 inch)
Jib/genoa halyard	27.4 m	(90.0 feet)	10 mm	(3/8 inch)
Spinnaker halyard	27.4 m	(90.0 feet)	10 mm	(3/8 inch)
Jib sheet	9.5 m	(31.2 feet)	12 mm	(1/2 inch)
Genoa sheet	9.5 m	(31.2 feet)	12 mm	(1/2 inch)
Mainsheet	23.8 m	(77.9 feet)	12 mm	(1/2 inch)
Spinnaker sheet	20.9 m	(68.6 feet)	12 mm	(1/2 inch)
Cunningham	3.0 m	(9.7 feet)	10 mm	(3/8 inch)
Kickingstrap	5.9 m	(19.4 feet)	10 mm	(3/8 inch)
Clew-outhaul	5.9 m	(19.4 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 Contest 31 HT 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.