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Review of Sigma 36 Mk II


Basic specs.

sail specifications
The Sigma 36 Mk II is a sailboat designed by the British maritime architect David Thomas in the early eighties.

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Hull

The hull is made of fibreglass. Generally, a hull made of fibreglass requires only a minimum of maintenance during the sailing season.


Keel

The Sigma 36 Mk II has been built with different keel alternatives.

Fin keel

One 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.

The boat can enter most marinas as the draft is just about 1.55 - 1.65 meter (5.09 - 5.39 ft) dependent on the load. See immersion rate below.

Fin keel

Another 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 boat can only enter major marinas as the draft is about 1.85 - 1.95 meter (6.07 - 6.37 ft) dependent on the load. See immersion rate below.


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 Mk II is 1.99, indicating that this boat could - if evaluated by this formula alone - 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 7.1 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 36 Mk II is about 200 kg/cm, alternatively 1123 lbs/inch.
Meaning: if you load 200 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 1123 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 36 Mk II is 24.1.

Low High 31% 0 50 100
Comparing this ratio with similar sailboats show that it is more comfortable than 31% of all similar sailboat designs. This comfort value is just below average.


L/B (Length Beam Ratio)

What is L/B (Length Beam Ratio)?

The l/b ratio for Sigma 36 Mk II is 3.13.

Slim Wide 62% 0 50 100
Compared with other similar sailboats it is more spacy than 62% 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 36 Mk II is 252 which categorizes this boat among 'light crusers & offshore racers'.

Heavy Light 50% 0 50 100
50% of all similar sailboat designs are categorized as heavier. This boat has a precise average ratio between displacement and length!


Maintenance

Bottom Paint

When buying anti-fouling bottom paint, it's nice to know how much to buy. The surface of the wet bottom is about 32m2 (344 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.


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
UsageLengthDiameter
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 sheet24.1 m(79.2 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.

Do you have changes/improvements you would like to share? Upload a photo and describe what you have done.



Finally

We are always looking for new photos. If you can contribute with photos for Sigma 36 Mk II 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