Review of Sigma 38 (Thomas)

Basic specs.

The Sigma 38 (Thomas) 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.

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 38 (Thomas) is 2.03, indicating that this boat would not be accepted to participate in ocean races.

Theoretical Maximum Hull Speed

What is Theoretical Maximum Hull Speed?

The theoretical maximal speed of a displacement boat of this length is 7.5 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.

Immersion rate

The immersion rate is defined as the weight required to sink the boat a certain level. The immersion rate for Sigma 38 (Thomas) is about 234 kg/cm, alternatively 1311 lbs/inch.
Meaning: if you load 234 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 1311 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.

Motion Comfort Ratio

What is Motion Comfort Ratio (MCR)?

The Motion Comfort Ratio for Sigma 38 (Thomas) is 23.0.

Comparing this ratio with similar sailboats show that it is more comfortable than 24% of all similar sailboat designs. This is a comfort value significantly below average.

L/B (Length Beam Ratio)

What is L/B (Length Beam Ratio)?

The l/b ratio for Sigma 38 (Thomas) is 3.13.

Compared with other similar sailboats it is more spacy than 66% of all other designs. It seems that the designer has chosen a slightly more spacy hull design.

D/L (Displacement Length Ratio)

What is Displacement Length Ratio?

The DL-ratio for Sigma 38 (Thomas) is 206 which categorizes this boat among 'light crusers & offshore racers'.

69% of all similar sailboat designs are categorized as heavier. A light displacement requires less sailarea and has higher accellerations.

Maintenance

Rig

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
Jib sheet	11.6 m	(38.0 feet)	14 mm	(0.55 inch)
Genoa sheet	11.6 m	(38.0 feet)	14 mm	(0.55 inch)
Mainsheet	28.9 m	(95.0 feet)	14 mm	(0.55 inch)
Spinnaker sheet	25.5 m	(83.6 feet)	14 mm	(0.55 inch)

Boat owner's ideas

This section is reserved boat owner's modifications, improvements, etc. Here you might find (or contribute with) inspiration for your boat.

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Finally

We are always looking for new photos. If you can contribute with photos for Sigma 38 (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.