Review of Sigma 33
Basic specs.
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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 Sigma 33 is 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 gennaker or a spinnaker for optimal speed.
The Sigma 33 has been built with different keel alternatives.
Fin keel
One option is 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 1.75 - 1.85 meter (5.74 - 6.04 ft) dependent on the load. See immersion rate below.
Full keel
Another option is a long keel. A full keel provide a better directional stability than a similar boat with a fin keel; on the other hand, better directional stability means also that the boat is more difficult to handle in a harbour with less space.
The boat can enter even shallow marinas as the draft is just about 1.46 - 1.56 meter (4.79 - 5.09 ft) dependent on the load. See immersion rate below.
Sigma 33 may be equipped with an inboard Volvo Penta 2002 diesel engine at 18 hp (13 kW). Calculated max speed is about 5.2 knots
Sailing characteristics
This section covers widely used rules of thumb to describe the sailing characteristics. Please note that even though the calculations are correct, the interpretation of the results might not be valid for extreme boats.
What is Capsize Screening Formula (CSF)?
The capsize screening value for Sigma 33 is 1.98, 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 6.9 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 Sigma 33 is about 171 kg/cm, alternatively 960 lbs/inch.
Meaning: if you load 171 kg cargo on the boat then it will sink 1 cm.
Alternatively, if you load 960 lbs cargo on the boat it will sink 1 inch.
Sailing statistics
This section is statistical comparison with similar boats of the same category. The basis of the following statistical computations is our unique database with more than 26,000 different boat types and 350,000 data points.
What is Motion Comfort Ratio (MCR)?
The Motion Comfort Ratio for Sigma 33 is 22.7.
What is L/B (Length Beam Ratio)?
The l/b ratio for Sigma 33 is 3.09.
The ballast ratio for Sigma 33 is 40%.
What is Displacement Length Ratio?
The DL-ratio for Sigma 33 is 234 which categorizes this boat among 'light crusers & offshore racers'.
What is SA/D (Sail Area Displacement ratio)?
The SA/D for Sigma 33 with ISO 8666 reference sail is 16.3, with a 135% genua the SA/D is 18.9.
What is Relative Speed Performance?
The Relative Speed Performance for Sigma 33 is 66
Maintenance
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.
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.
| Usage | Length | Diameter | ||
| Mainsail halyard | 30.2 m | (99.2 feet) | 10 mm | (3/8 inch) |
| Jib/genoa halyard | 30.2 m | (99.2 feet) | 10 mm | (3/8 inch) |
| Spinnaker halyard | 30.2 m | (99.2 feet) | 10 mm | (3/8 inch) |
| Jib sheet | 9.9 m | (32.4 feet) | 12 mm | (1/2 inch) |
| Genoa sheet | 9.9 m | (32.4 feet) | 12 mm | (1/2 inch) |
| Mainsheet | 24.7 m | (81.0 feet) | 12 mm | (1/2 inch) |
| Spinnaker sheet | 21.7 m | (71.3 feet) | 12 mm | (1/2 inch) |
| Cunningham | 4.0 m | (13.0 feet) | 10 mm | (3/8 inch) |
| Kickingstrap | 7.9 m | (26.0 feet) | 10 mm | (3/8 inch) |
| Clew-outhaul | 7.9 m | (26.0 feet) | 10 mm | (3/8 inch) |
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