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Review of Dufour 425 Grand Large


Basic specs.

sail specifications
The Dufour 425 Grand Large is a large sailboat designed by the Italian maritime architect Umberto Felci.

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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.
The hull is a double hull 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.


Interior

The boat is equipped with 6-8 berths and 440.0 liter fresh water capacity.


Rig

The Dufour 425 Grand Large is equipped with a fractional rig. A fractional rig has smaller headsails which make tacking easier, which is an advantage for cruisers and racers, of course. The downside is that having the wind from behind often requires a gennaker or a spinnaker for optimal speed.


Keel

The Dufour 425 Grand Large has been built with different keel alternatives.

Unknown keel type

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.

The boat can only enter major marinas as the draft is about 2.10 - 2.20 meter (6.89 - 7.19 ft) dependent on the load. See immersion rate below.

Unknown keel type

Dufour 425 Grand Large can enter most marinas as the draft is just about 1.70 - 1.80 meter (5.58 - 5.88 ft) dependent on the load. See immersion rate below.


Engine

The boat may be equipped with an inboard Volvo Penta diesel engine at 40 hp (29 kW). Calculated max speed is about 6.5 knots

The transmission is a saildrive.

The fuel tank has a capacity of 160.0 liters (42 US gallons, 35 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 Dufour 425 Grand Large is 2.03, indicating that this boat would not be accepted to participate in ocean races.


EU classification

Dufour 425 Grand Large holds a CE certification:

The boat is by European Union certified as Class A. OCEAN:
Designed for extended voyages where conditions may exceed wind force 8 (Beaufort scale) and significant wave heights of 4 m and above but excluding abnormal conditions, and vessels largely self-sufficient.


Theoretical Maximum Hull Speed

What is Theoretical Maximum Hull Speed?

The theoretical maximal speed of a displacement boat of this length is 8.1 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.


Immersion rate

The immersion rate is defined as the weight required to sink the boat a certain level. The immersion rate for Dufour 425 Grand Large is about 313 kg/cm, alternatively 1752 lbs/inch.
Meaning: if you load 313 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 1752 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 Dufour 425 Grand Large is 24.0.

Low High 21% 0 50 100
Comparing this ratio with similar sailboats show that it is more comfortable than 21% of all similar sailboat designs. This is a comfort value significantly below average.


L/B (Length Beam Ratio)

What is L/B (Length Beam Ratio)?

The l/b ratio for Dufour 425 Grand Large is 3.03.

Slim Wide 79% 0 50 100
Compared with other similar sailboats it is more spacy than 79% 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 Dufour 425 Grand Large is 28%.

Low High 4% 0 50 100
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 Dufour 425 Grand Large is 173 which categorizes this boat among 'light racers'.

Heavy Light 82% 0 50 100
82% 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 Dufour 425 Grand Large with ISO 8666 reference sail is 16.0, with a 135% genua the SA/D is 18.9.

Low High 27% 0 50 100
The SA/D ratio indicates that it is faster than 27% of all similar sailboat designs in light wind.


Over- / underrigged

Low High 86% 0 50 100
The Dufour 425 Grand Large has more rig than 86% of all similar sailboats, which indicates that the boat is significantly overrigged.


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 53m2 (570 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 fractional rig.

mainsail specifications headsail specifications

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
UsageLengthDiameter
Mainsail halyard 35.5 m(116.5 feet)12 mm(1/2 inch)
Jib/genoa halyard35.5 m(116.5 feet)12 mm(1/2 inch)
Spinnaker halyard35.5 m(116.5 feet)12 mm(1/2 inch)
Jib sheet 12.6 m(41.3 feet)14 mm(0.55 inch)
Genoa sheet12.6 m(41.3 feet)14 mm(0.55 inch)
Mainsheet 31.5 m(103.3 feet)14 mm(0.55 inch)
Spinnaker sheet27.7 m(90.9 feet)14 mm(0.55 inch)
Cunningham4.7 m(15.4 feet)12 mm(1/2 inch)
Kickingstrap9.4 m(30.8 feet)12 mm(1/2 inch)
Clew-outhaul9.4 m(30.8 feet)12 mm(1/2 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 Dufour 425 Grand Large 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