Review of Sun Light 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. Teak has the advantage of being naturally very oily and therefore water-repellent, which is suitable on boats.
The boat is equipped with 3 cabins, 6 berths, a galley, 100.0 liter fresh water capacity and toilet facility.

The Sun Light 31 is 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 Sun Light 31 has been built with different keel alternatives.

CentreBoard

One option is a centreboard keel. A centreboard keel is a pivoting lifting keel, allowing to sail both coastal and inland waters.

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 even shallow marinas as the draft is just about 1.10 - 1.20 meter (3.61 - 3.91 ft) dependent on the load. See immersion rate below.

Deep keel

Another option is a deep keel. A deep keel provide a better healing moment than a shallow 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.

Sun Light 31 can enter most marinas as the draft is just about 1.78 - 1.88 meter (5.84 - 6.14 ft) dependent on the load. See immersion rate below.

Shallow keel

Another option is a shallow keel. A shallow keel allow to sail both coastal and inland waters.

This keel is also made of iron.

The boat can enter even shallow marinas as the draft is just about 1.45 - 1.55 meter (4.76 - 5.06 ft) dependent on the load. See immersion rate below.

Unknown keel type

The boat can enter most marinas as the draft is just about 1.51 - 1.61 meter (4.95 - 5.25 ft) dependent on the load. See immersion rate below.

Fin keel

Another 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.

This keel is also made of iron.

Sun Light 31 can enter most marinas as the draft is just about 1.78 - 1.88 meter (5.84 - 6.14 ft) dependent on the load. See immersion rate below.

The boat may be equipped with an inboard Volvo Penta 2002 diesel engine at 18 hp (13 kW). The speed is 7.0 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 45.0 liters (11 US gallons, 9 imperial gallons).

What is Capsize Screening Formula (CSF)?

The capsize screening value for Sun Light 31 is 2.21, 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 6.7 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 Sun Light 31 is about 166 kg/cm, alternatively 933 lbs/inch.
Meaning: if you load 166 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 933 lbs cargo on the boat it will sink 1 inch.

What is Motion Comfort Ratio (MCR)?

The Motion Comfort Ratio for Sun Light 31 is 17.5.

What is L/B (Length Beam Ratio)?

The l/b ratio for Sun Light 31 is 2.83.

What is a Ballast Ratio?

The ballast ratio for Sun Light 31 is 42%.

What is Displacement Length Ratio?

The DL-ratio for Sun Light 31 is 195 which categorizes this boat among 'light racers'.

When buying anti-fouling bottom paint, it's nice to know how much to buy. The surface of the wet bottom is about 30m² (322 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 Sun Light 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.