Review of Onyx 38

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

The interior is like nearly all boats made of wood.
The boat is equipped with one cabin and 5-6 berths.

Note: the boat has also been sold to be self-made/-interiored, which means that the quality of each boat may vary.

Fin keel

The Onyx 38 is equipped with 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 keel is made of lead. Compared with iron, lead has the advantage of being 44% heavier, which allows a smaller keel and hence less water resistance and higher speed.

Onyx 38 can enter most marinas as the draft is just about 1.70 - 1.80 meter (5.58 - 5.88 ft) dependent on the load. See immersion rate below.

What is Capsize Screening Formula (CSF)?

The capsize screening value for Onyx 38 is 1.71, indicating that this boat could - if evaluated by this formula alone - be accepted to participate in ocean races.

What is Theoretical Maximum Hull Speed?

The theoretical maximal speed of a displacement boat of this length is 7.9 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.

The immersion rate is defined as the weight required to sink the boat a certain level. The immersion rate for Onyx 38 is about 192 kg/cm, alternatively 1075 lbs/inch.
Meaning: if you load 192 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 1075 lbs cargo on the boat it will sink 1 inch.

What is Motion Comfort Ratio (MCR)?

The Motion Comfort Ratio for Onyx 38 is 21.5.

Comparing this ratio with similar sailboats show that it is more comfortable than 15% of all similar sailboat designs. This is a comfort value significantly below average.

What is L/B (Length Beam Ratio)?

The l/b ratio for Onyx 38 is 4.29.

Compared with other similar sailboats it is slimmer than 100% 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'.

What is a Ballast Ratio?

The ballast ratio for Onyx 38 is 49%.

This ballast ratio shows a righting moment that is higher than 90% of all similar sailboat designs. A righting moment (ability to resist heeling) significantly above average.

What is Displacement Length Ratio?

The DL-ratio for Onyx 38 is 101 which categorizes this boat among 'ultra light racers'.

96% of all similar sailboat designs are categorized as heavier. A light displacement requires less sailarea and has higher accellerations.

What is Relative Speed Performance?

The Relative Speed Performance for Onyx 38 is 76

The relative speed performance is 76 which means that a it is faster than 76% of all similar sailboat designs.

When buying anti-fouling bottom paint, it's nice to know how much to buy. The surface of the wet bottom is about 35m² (376 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.

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.

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.

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

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