Review of Sigma 36

Basic specs.

The Sigma 36 is a sailboat designed by the British maritime architect David Thomas.

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Hull

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.

Interior

The boat is equipped with 8 berths.

Rig

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.

Keel

The Sigma 36 has been built with more than one type of keel.

One option is a long keel. A long 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.

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 long keel.

The boat can only enter major marinas as the draft is about 1.96 - 2.06 meter (6.43 - 6.73 ft) dependent on the load. See immersion rate below.

Engine

Sigma 36 is typically equipped with an inboard Volvo Penta MD11 diesel engine at 23.0 hp (17 kW).

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.

Stability and Safety

What is Capsize Screening Formula (CSF)?

The capsize screening value for Sigma 36 is 1.98, indicating that this boat could - if evaluated by this formula alone - be accepted to participate in ocean races.

Immersion rate

The immersion rate is defined as the weight required to sink the boat a certain level. The immersion rate for Sigma 36 is about 255 kg/cm, alternatively 1432 lbs/inch.
Meaning: if you load 255 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 1432 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.

L/B (Length Beam Ratio)

What is L/B (Length Beam Ratio)?

The l/b ratio for Sigma 36 is 3.15.

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

SA/D (Sail Area Displacement ratio)

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

The SA/D for Sigma 36 with ISO 8666 reference sail is 18.1, with a 135% genua the SA/D is 20.8.

The SA/D ratio indicates that it is faster than 66% of all similar sailboat designs in light wind.

Maintenance

Rig

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.

**Guiding dimensions of running rig**
Usage	Length		Diameter
Mainsail halyard	35.6 m	(116.8 feet)	12 mm	(1/2 inch)
Jib/genoa halyard	35.6 m	(116.8 feet)	12 mm	(1/2 inch)
Spinnaker halyard	35.6 m	(116.8 feet)	12 mm	(1/2 inch)
Jib sheet	11.0 m	(36.0 feet)	14 mm	(0.55 inch)
Genoa sheet	11.0 m	(36.0 feet)	14 mm	(0.55 inch)
Mainsheet	27.4 m	(90.0 feet)	14 mm	(0.55 inch)
Spinnaker sheet	24.1 m	(79.2 feet)	14 mm	(0.55 inch)
Cunningham	4.7 m	(15.3 feet)	12 mm	(1/2 inch)
Kickingstrap	9.3 m	(30.6 feet)	12 mm	(1/2 inch)
Clew-outhaul	9.3 m	(30.6 feet)	12 mm	(1/2 inch)

Boat owner's ideas

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.

Finally

We are always looking for new photos. If you can contribute with photos for Sigma 36 (Thomas) 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.

References

[Ref 1]: ISO 8666 Small craft — Principal data.
[Ref 3]: ISO 12215-5 Small craft — Hull construction and scantlings.