Review of Sunwind 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 deck is a double deck which improves the indoor climate.

The interior is like most other boats made of teak.
The boat is equipped with 5 berths, a galley and toilet facility.

The boat 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 genaker or a spinnaker for optimal speed.

The Sunwind 31 is equipped with a fin keel. The fin keel is the most common keel and provides splendid manoeuvrability. The downside is that it has less directional stability than 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 enter most marinas as the draft is just about 1.65 - 1.75 meter (5.41 - 5.71 ft) dependent on the load. See immersion rate below.

Sunwind 31 is typically equipped with an inboard Volvo Penta engine at 18.0 hp (13 kW), which gives a max speed about 5.3 knots.

The fuel tank which is made of steel has a capacity of 20.0 liters (5 US gallons, 4 imperial gallons).

What is Capsize Screening Formula (CSF)?

The capsize screening value for Sunwind 31 is 1.87, 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 6.5 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 Sunwind 31 is about 140 kg/cm, alternatively 788 lbs/inch.
Meaning: if you load 140 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 788 lbs cargo on the boat it will sink 1 inch.

What is Motion Comfort Ratio (MCR)?

The Motion Comfort Ratio for Sunwind 31 is 24.8.

Comparing this ratio with similar sailboats show that it is more comfortable than 58% of all similar sailboat designs. This comfort value is just above average.

What is L/B (Length Beam Ratio)?

The l/b ratio for Sunwind 31 is 3.22.

Compared with other similar sailboats it is slimmer than 58% of all other designs. It seems that the designer has chosen a slightly more speedy hull design.

What is a Ballast Ratio?

The ballast ratio for Sunwind 31 is 39%.

This ballast ratio shows a righting moment that is higher than 38% of all similar sailboat designs. A righting moment (ability to resist heeling) just below average.

What is Displacement Length Ratio?

The DL-ratio for Sunwind 31 is 277 which categorizes this boat among 'medium weight cruisers'.

38% of all similar sailboat designs are categorized as heavier. A heavy displacement combined with smaller water plane area has lower acceleration and is more comfortable.

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

The SA/D for Sunwind 31 with ISO 8666 reference sail is 15.6, with a 135% genua the SA/D is 18.0.

The SA/D ratio indicates that it is faster than 42% of all similar sailboat designs in light wind.

The Sunwind 31 has more rig than 58% of all similar sailboats, which indicates that the boat is slightly overrigged.

What is Relative Speed Performance?

The Relative Speed Performance for Sunwind 31 is 50

The relative speed performance is 50 which means that a it is faster than 50% of all similar sailboat designs.

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 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.

This section shown boat owner's changes, improvements, etc. Here you might find inspiration for your boat.

Do you have changes/improvements you would like to share? Upload a photo and describe what to look for.

We are always looking for new photos. If you can contribute with photos for Sunwind 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.