Review of Compass 31
Basic specs.
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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.
Both the hull and the deck is a sandwich construction 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 boat is equipped with 7-8 berths, a galley, 200.0 liter fresh water capacity and toilet facility.
The Compass 31 is equipped with a ketch rig. A ketch rig is generally considered easier to handle, because the sails are smaller, and because it can sail on most points to the wind with one sail completely taken down for repair or while reefing. The sail configuration of a ketch allows for better comfort and stability when sailing downwind or on a broad reach.
Fin keel
The Compass 31 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 even shallow marinas as the draft is just about 1.40 - 1.50 meter (4.59 - 4.89 ft) dependent on the load. See immersion rate below.
Compass 31 may be equipped with an inboard Volvo Penta engine at 36 hp (26 kW). The speed is 8.0 knots.
The transmission is a shaft drive. A shaft drive will in the long run require less maintenance than other types of drive e.g. a sail drive.
The fuel tank, which is made of fibreglass, has a capacity of 155.0 liters (40 US gallons, 34 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.
What is Capsize Screening Formula (CSF)?
The capsize screening value for Compass 31 is 1.77, indicating that this boat could - if evaluated by this formula alone - be accepted to participate in ocean races.
What is Theoretical Maximum Hull Speed?
The theoretical maximal speed of a displacement boat of this length is 7.1 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.
The immersion rate is defined as the weight required to sink the boat a certain level.
The immersion rate for Compass 31 is about 176 kg/cm, alternatively 988 lbs/inch.
Meaning: if you load 176 kg cargo on the boat then it will sink 1 cm.
Alternatively, if you load 988 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.
What is Motion Comfort Ratio (MCR)?
The Motion Comfort Ratio for Compass 31 is 29.3.
What is L/B (Length Beam Ratio)?
The l/b ratio for Compass 31 is 3.06.
What is Displacement Length Ratio?
The DL-ratio for Compass 31 is 249 which categorizes this boat among 'light crusers & offshore racers'.
Maintenance
When buying anti-fouling bottom paint, it's nice to know how much to buy.
The surface of the wet bottom is about 29m2 (312 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.
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.
| Usage | Length | Diameter | ||
| 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) |
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