The Delta 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 long keel.
The keel is made of iron. Many people prefer lead keel in favour of iron. The main argument is that lead is much heavier than iron and a lead keel can therefore be made smaller which again result in less wet surface, i.e. less drag. In fact iron is quite heavy, just 30% less heavy than lead, so the advantage of a lead keel is often overstated. As the surface of a fin type keel is just a fraction of the total wet surface, the difference between an iron keel and a lead keel can in reality be ignored for cruising yachts.
The boat can only enter major marinas as the draft is about 1.80 - 1.90 meter (5.91 - 6.21 ft) dependent on the load. See immersion rate below.
The boat is typically equipped with an inboard Yanmar 1GM diesel engine at 8.0 hp (5 kW), which gives a max speed about 3.6 knots.
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 Delta 31 is 1.95, 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 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.
The immersion rate is defined as the weight required to sink the boat a certain level.
The immersion rate for Delta 31 is about 154 kg/cm, alternatively 866 lbs/inch.
Meaning: if you load 154 kg cargo on the boat then it will sink 1 cm.
Alternatively, if you load 866 lbs cargo on the boat it will sink 1 inch.
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 Delta 31 is 23.1.
What is L/B (Length Beam Ratio)?
The l/b ratio for Delta 31 is 3.08.
The ballast ratio for Delta 31 is 41%.
What is Displacement Length Ratio?
The DL-ratio for Delta 31 is 247 which categorizes this boat among 'light crusers & offshore racers'.
What is SA/D (Sail Area Displacement ratio)?
The SA/D for Delta 31 with ISO 8666 reference sail is 16.6, with a 135% genua the SA/D is 19.3.
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.
Dimensions of sail for fractional 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.
Usage | Length | Diameter | ||
Mainsail halyard | 30.1 m | (98.6 feet) | 10 mm | (3/8 inch) |
Jib/genoa halyard | 30.1 m | (98.6 feet) | 10 mm | (3/8 inch) |
Spinnaker halyard | 30.1 m | (98.6 feet) | 10 mm | (3/8 inch) |
Jib sheet | 9.3 m | (30.7 feet) | 12 mm | (1/2 inch) |
Genoa sheet | 9.3 m | (30.7 feet) | 12 mm | (1/2 inch) |
Mainsheet | 23.4 m | (76.7 feet) | 12 mm | (1/2 inch) |
Spinnaker sheet | 20.6 m | (67.5 feet) | 12 mm | (1/2 inch) |
Cunningham | 3.8 m | (12.5 feet) | 10 mm | (3/8 inch) |
Kickingstrap | 7.6 m | (24.9 feet) | 10 mm | (3/8 inch) |
Clew-outhaul | 7.6 m | (24.9 feet) | 10 mm | (3/8 inch) |
This section shown boat owner's changes, improvements, etc. Here you might find inspiration for your boat.
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