Review of Dufour 304 Trophy

Both the hull and the deck is made of fibreglass. A hull made of fibreglass requires only a minimum of maintenance during the sailing season.

The Dufour 304 Trophy has been built with different keel alternatives.

Fin keel

One option is 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 only enter major marinas as the draft is about 1.85 - 1.95 meter (6.07 - 6.37 ft) dependent on the load. See immersion rate below.

Fin keel

Another option is a fin keel.

The boat can enter even shallow marinas as the draft is just about 1.46 - 1.56 meter (4.79 - 5.09 ft) dependent on the load. See immersion rate below.

What is Capsize Screening Formula (CSF)?

The capsize screening value for Dufour 304 Trophy is 2.23, indicating that this boat would not 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 6.8 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 Dufour 304 Trophy is about 177 kg/cm, alternatively 994 lbs/inch.
Meaning: if you load 177 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 994 lbs cargo on the boat it will sink 1 inch.

What is Motion Comfort Ratio (MCR)?

The Motion Comfort Ratio for Dufour 304 Trophy is 17.9.

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.

What is L/B (Length Beam Ratio)?

The l/b ratio for Dufour 304 Trophy is 2.68.

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.

What is a Ballast Ratio?

The ballast ratio for Dufour 304 Trophy is 35%.

This ballast ratio is higher than 18% of all similar sailboat designs. Since the ballast ratio and the righting moment (i.e. better ability to resist heeling) is strongly correlated, a ballast ratio significantly below average indicates a very low ability to resist heeling.

What is Displacement Length Ratio?

The DL-ratio for Dufour 304 Trophy is 199 which categorizes this boat among 'moderate racers'.

76% of all similar sailboat designs are categorized as heavier. A light displacement requires less sailarea and has higher accellerations.

When buying anti-fouling bottom paint, it's nice to know how much to buy. The surface of the wet bottom is about 31m² (333 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.

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.

We are always looking for new photos. If you can contribute with photos for Dufour 304 Trophy 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.

[Ref 1]: ISO 8666 Small craft — Principal data.
[Ref 3]: ISO 12215-5 Small craft — Hull construction and scantlings.