Review of Sirocco 31 Mk II

The hull 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 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 boat is equipped with one cabin, 5 berths, a galley, 50.0 liter fresh water capacity and toilet facility.

The Sirocco 31 Mk II 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.

Keel of Sirocco 31 Mk II anno 1973.

Fin keel

The Sirocco 31 Mk II 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 enter most marinas as the draft is just about 1.70 - 1.80 meter (5.58 - 5.88 ft) dependent on the load. See immersion rate below.

Sirocco 31 Mk II may be equipped with an inboard Volvo Penta 2001 diesel engine at 9 hp (6 kW). Max speed is 5.0 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 30.0 liters (7 US gallons, 6 imperial gallons).

What is Capsize Screening Formula (CSF)?

The capsize screening value for Sirocco 31 Mk II is 1.96, indicating that this boat could - if evaluated by this formula alone - be accepted to participate in ocean races.

The immersion rate is defined as the weight required to sink the boat a certain level. The immersion rate for Sirocco 31 Mk II is about 180 kg/cm, alternatively 1008 lbs/inch.
Meaning: if you load 180 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 1008 lbs cargo on the boat it will sink 1 inch.

What is L/B (Length Beam Ratio)?

The l/b ratio for Sirocco 31 Mk II is 3.43.

What is a Ballast Ratio?

The ballast ratio for Sirocco 31 Mk II is 46%.

SA/D (Sail Area Displacement ratio)
Indicates how fast the boat is in light wind:
- Cruising Boats have ratios 10-15
- Cruiser-Racers have ratios 16-20
- Racers have ratios above 20
- High-Performance Racers have ratios above 24
Sail-area/displacement ratio (SA/D ratio): 14.27

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.

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