Review of Backman 21

Basic specs.

The Backman 21 aka Z21 is a small sailboat designed by the maritime architect Hans Backman in the mid 2000.

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Keel

The boat can enter even shallow marinas as the draft is just about 0.40 - 0.50 meter (1.31 - 1.61 ft) dependent on the load. See immersion rate below.

Engine

The boat is typically equipped with an engine.

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.

Immersion rate

The immersion rate is defined as the weight required to sink the boat a certain level. The immersion rate for Backman 21 is about 106 kg/cm, alternatively 594 lbs/inch.
Meaning: if you load 106 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 594 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.

L/B (Length Beam Ratio)

What is L/B (Length Beam Ratio)?

The l/b ratio for Backman 21 is 2.75.

Compared with other similar sailboats it is more spacy than 58% 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 Backman 21 is 36%.

This ballast ratio shows a righting moment that is higher than 42% of all similar sailboat designs. A righting moment (ability to resist heeling) just below average.

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	6.6 m	(21.7 feet)	10 mm	(3/8 inch)
Genoa sheet	6.6 m	(21.7 feet)	10 mm	(3/8 inch)
Mainsheet	16.5 m	(54.1 feet)	10 mm	(3/8 inch)
Spinnaker sheet	14.5 m	(47.6 feet)	10 mm	(3/8 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.

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Finally

We are always looking for new photos. If you can contribute with photos for Backman 21 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.