Review of Sensei 9M

Basic specs.

The Sensei 9M is a sailboat designed by the Italian maritime architect bureau Felci Yacht Design.

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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. 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.

Interior

The boat is equipped with 4 berths.

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 Sensei 9M is 1.95, indicating that this boat could - if evaluated by this formula alone - be accepted to participate in ocean races.

EU classification

Sensei 9M holds two CE certifications:

The boat is by European Union certified as Class A. OCEAN:

Designed for extended voyages where conditions may exceed wind force 8 (Beaufort scale) and significant wave heights of 4 m and above but excluding abnormal conditions, and vessels largely self-sufficient.

The boat is by European Union certified as Class B. OFFSHORE:

Designed for offshore voyages where conditions up to, and including, wind force 8 (Beaufort scale) and significant wave heights up to, and including, 4 m may be experienced.

Theoretical Maximum Hull Speed

What is Theoretical Maximum Hull Speed?

The theoretical maximal speed of a displacement boat of this length is 7.3 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 Sensei 9M is about 152 kg/cm, alternatively 853 lbs/inch.
Meaning: if you load 152 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 853 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 Sensei 9M is 14.4.

Comparing this ratio with similar sailboats show that it is more comfortable than 7% 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 Sensei 9M is 3.96.

Compared with other similar sailboats it is slimmer than 96% of all other designs. It seems that the designer has chosen a significantly more speedy hull design. This type of design is also referred to as 'needle'.

D/L (Displacement Length Ratio)

What is Displacement Length Ratio?

The DL-ratio for Sensei 9M is 79 which categorizes this boat among 'ultra light racers'.

98% 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	9.9 m	(32.5 feet)	12 mm	(1/2 inch)
Genoa sheet	9.9 m	(32.5 feet)	12 mm	(1/2 inch)
Mainsheet	24.8 m	(81.2 feet)	12 mm	(1/2 inch)
Spinnaker sheet	21.8 m	(71.5 feet)	12 mm	(1/2 inch)

Boat owner's ideas

This section is reserved boat owner's changes, 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 Sensei 9M 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.