Review of Møn 431

Both the hull and the deck is made of hand laid fibreglass. Generally, a hull made of hand laid 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.
The deck is a double deck which improves the indoor climate.

Interior of Møn 431 anno 1989.

The boat is equipped with 0 cabins, 11 berths, a galley, 400.0 liter fresh water capacity and toilet facility.

Front cabin of Møn 431 anno 1989.

Galley of Møn 431 anno 1989.

Fin keel

The Møn 431 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 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 1.85 - 1.95 meter (6.07 - 6.37 ft) dependent on the load. See immersion rate below.

Møn 431 may be equipped with an inboard Yanmar diesel engine at 44 hp (32 kW). The speed is 8.5 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 stainless steel, has a capacity of 224.0 liters (59 US gallons, 49 imperial gallons).

What is Capsize Screening Formula (CSF)?

The capsize screening value for Møn 431 is 1.83, 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 7.8 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 Møn 431 is about 271 kg/cm, alternatively 1521 lbs/inch.
Meaning: if you load 271 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 1521 lbs cargo on the boat it will sink 1 inch.

What is Motion Comfort Ratio (MCR)?

The Motion Comfort Ratio for Møn 431 is 31.1.

What is L/B (Length Beam Ratio)?

The l/b ratio for Møn 431 is 3.28.

What is a Ballast Ratio?

The ballast ratio for Møn 431 is 42%.

What is Displacement Length Ratio?

The DL-ratio for Møn 431 is 247 which categorizes this boat among 'light crusers & offshore racers'.

When buying anti-fouling bottom paint, it's nice to know how much to buy. The surface of the wet bottom is about 45m² (484 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 Møn 431 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.