Review of Mantra 28

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 boat is equipped with 4 berths and toilet facility.
The headroom is above average

The boat equipped with a fractional rig. A fractional rig has smaller headsails which make tacking easier, which is an advantage for cruisers and racers, of course. The downside is that having the wind from behind often requires a genaker or a spinnaker for optimal speed.

The boat is typically equipped with an inboard Yanmar 1GM10 diesel engine.

The transmission is a saildrive.

The fuel tank has a capacity of 33 liters (8 US gallons, 7 imperial gallons).

What is Capsize Screening Formula (CSF)?

The capsize screening value for Mantra 28 is 1.84, indicating that this boat could - if evaluated by this formula alone - be accepted to participate in ocean races.

Mantra 28 holds one CE certification:

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

What is Theoretical Maximum Hull Speed?

The theoretical maximal speed of a displacement boat of this length is 6.8 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 Mantra 28 is about 141 kg/cm, alternatively 790 lbs/inch.
Meaning: if you load 141 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 790 lbs cargo on the boat it will sink 1 inch.

What is Motion Comfort Ratio (MCR)?

The Motion Comfort Ratio for Mantra 28 is 23.3.

Comparing this ratio with similar sailboats show that it is more comfortable than 62% of all similar sailboat designs. This comfort value is just above average.

What is L/B (Length Beam Ratio)?

The l/b ratio for Mantra 28 is 3.12.

Compared with other similar sailboats it is slimmer than 58% of all other designs. It seems that the designer has chosen a slightly more speedy hull design.

What is Displacement Length Ratio?

The DL-ratio for Mantra 28 is 199 which categorizes this boat among 'light racers'.

73% of all similar sailboat designs are categorized as heavier. A light displacement requires less sailarea and has higher accellerations.

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 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.

We are always looking for new photos. If you can contribute with photos for Mantra 28 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.