Review of Moody 31

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.

The boat is equipped with 2 cabins, 4-6 berths, a galley and toilet facility.

The boat equipped with a masthead rig. The advantage of a masthead rig is its simplicity and the fact that a given sail area - compared with a fractional rig - can be carried lower and thus with less heeling moment.

The Moody 31 is equipped with a bilge keel. A bilge keel is a double keel, which allows the boat to be beached. Bilge keels are the most popular keel for tidal waters.

The boat can enter even shallow marinas as the draft is just about 1.12 - 1.22 meter (3.67 - 3.97 ft) dependent on the load. See immersion rate below.

Moody 31 is typically equipped with an inboard Volvo Penta 2003 diesel engine at 28.0 hp (20 kW), which gives a max speed about 6.7 knots.

The fuel tank has a capacity of 91 liters (24 US gallons, 20 imperial gallons).

What is Capsize Screening Formula (CSF)?

The capsize screening value for Moody 31 is 2.04, 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 Moody 31 is about 166 kg/cm, alternatively 930 lbs/inch.
Meaning: if you load 166 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 930 lbs cargo on the boat it will sink 1 inch.

What is Motion Comfort Ratio (MCR)?

The Motion Comfort Ratio for Moody 31 is 21.7.

Comparing this ratio with similar sailboats show that it is more comfortable than 38% of all similar sailboat designs. This comfort value is just below average.

What is L/B (Length Beam Ratio)?

The l/b ratio for Moody 31 is 2.93.

Compared with other similar sailboats it is more spacy than 69% of all other designs. It seems that the designer has chosen a slightly more spacy hull design.

What is a Ballast Ratio?

The ballast ratio for Moody 31 is 41%.

This ballast ratio shows a righting moment that is higher than 50% of all similar sailboat designs. This righting moment (ability to resist heeling) is spot on average!

What is Displacement Length Ratio?

The DL-ratio for Moody 31 is 237 which categorizes this boat among 'light crusers & offshore racers'.

58% of all similar sailboat designs are categorized as heavier. A light displacement requires less sailarea and has higher accellerations.

What is SA/D (Sail Area Displacement ratio)?

The SA/D for Moody 31 with ISO 8666 reference sail is 16.3, with a 135% genua the SA/D is 19.5.

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

The Moody 31 has more rig than 96% of all similar sailboats, which indicates that the boat is significantly overrigged.

When buying anti-fouling bottom paint, it's nice to know how much to buy. The surface of the wet bottom is about 25m² (269 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 masthead 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.

This section is reserved boat owner's changes, 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 Moody 31 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.