Review of OVNI 495

Basic specs.

The OVNI 495 is a large sailboat designed by the French maritime architect Philippe Briand in the early eighties. The OVNI 495 is built by the French yard SAS Alubat Chantier Naval.

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Hull

The hull is made of aluminium. Aluminum is strong and forgiving. Where an impact on a fiberglass hull will result in major gelcoat damage and possible cracking, an aluminum hull will probably only have a scratch or a small bend. The only concern is electrolysis. Ensure that you have proper sacrificial anodes installed.

Interior

The boat is equipped with 6/8 berths and 600.0 liter fresh water capacity.

Keel

CentreBoard

The OVNI 495 is equipped with a centreboard keel. A centreboard keel is a pivoting lifting keel, allowing to sail both coastal and inland waters.

The boat can enter even shallow marinas as the draft is just about 0.95 - 1.05 meter (3.12 - 3.42 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 OVNI 495 is 1.92, indicating that this boat could - if evaluated by this formula alone - be accepted to participate in ocean races.

EU classification

OVNI 495 holds a CE certification:

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.

Theoretical Maximum Hull Speed

What is Theoretical Maximum Hull Speed?

The theoretical maximal speed of a displacement boat of this length is 8.6 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 OVNI 495 is about 367 kg/cm, alternatively 2056 lbs/inch.
Meaning: if you load 367 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 2056 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 OVNI 495 is 27.2.

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 OVNI 495 is 3.33.

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.

Ballast Ratio

What is a Ballast Ratio?

The ballast ratio for OVNI 495 is 36%.

This ballast ratio shows a righting moment that is higher than 54% of all similar sailboat designs. A righting moment (ability to resist heeling) just above average.

D/L (Displacement Length Ratio)

What is Displacement Length Ratio?

The DL-ratio for OVNI 495 is 167 which categorizes this boat among 'light racers'.

76% of all similar sailboat designs are categorized as heavier. A light displacement requires less sailarea and has higher accellerations.

SA/D (Sail Area Displacement ratio)

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

The SA/D for OVNI 495 with ISO 8666 reference sail is 18.9, with a 135% genua the SA/D is 22.5.

The SA/D ratio indicates that it is faster than 50% of all similar sailboat designs in light wind.

Over- / underrigged

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 68m² (731 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

Dimensions of sail.

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	42.9 m	(140.7 feet)	14 mm	(0.55 inch)
Jib/genoa halyard	42.9 m	(140.7 feet)	14 mm	(0.55 inch)
Spinnaker halyard	42.9 m	(140.7 feet)	14 mm	(0.55 inch)
Jib sheet	14.5 m	(47.6 feet)	16 mm	(5/8 inch)
Genoa sheet	14.5 m	(47.6 feet)	16 mm	(5/8 inch)
Mainsheet	36.2 m	(118.9 feet)	16 mm	(5/8 inch)
Spinnaker sheet	31.9 m	(104.7 feet)	16 mm	(5/8 inch)
Cunningham	5.4 m	(17.6 feet)	14 mm	(0.55 inch)
Kickingstrap	10.7 m	(35.2 feet)	14 mm	(0.55 inch)
Clew-outhaul	10.7 m	(35.2 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 OVNI 495 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.