Review of Thumb 15

Basic specs.

The Thumb 15 is a small sailing dinghy designed by the Dutch maritime architect E. G. van de Stadt in the late seventies.

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Hull

The hull is made of plywood.

Rig

The Thumb 15 is 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 gennaker or a spinnaker for optimal speed.

Keel

CentreBoard

The Thumb 15 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 sail close to the beach as the draft is just 0.12 - 0.22 meter (0.39 - 0.69 ft) dependent of 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.

Immersion rate

The immersion rate is defined as the weight required to sink the boat a certain level. The immersion rate for Thumb 15 is about 50 kg/cm, alternatively 283 lbs/inch.
Meaning: if you load 50 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 283 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 Thumb 15 is 2.50.

Compared with other similar dinghies it is more spacy than 66% of all other designs. It seems that the designer has chosen a slightly more spacy hull design.

Maintenance

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.

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Finally

We are always looking for new photos. If you can contribute with photos for Thumb 15 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.