Review of Terhi 620

Basic specs.

The Terhi 620 is a small sailboat designed by the Finnish maritime architect Love Still in the mid seventies.

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Interior

The boat is equipped with a galley and toilet facility.
The headroom is above average

Keel

The Terhi 620 is equipped with a fin keel. A boat with a fin keel is more manoeuvrable but has less directional stability than a similar boat with a long keel.

The boat can enter even shallow marinas as the draft is just about 1.20 - 1.30 meter (3.94 - 4.24 ft) dependent on the load. See immersion rate below.

Engine

Terhi 620 is typically equipped with an inboard Vire 7 engine at 7.0 hp (5 kW).

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 Terhi 620 is 2.16, indicating that this boat would not be accepted to participate in ocean races.

Immersion rate

The immersion rate is defined as the weight required to sink the boat a certain level. The immersion rate for Terhi 620 is about 99 kg/cm, alternatively 558 lbs/inch.
Meaning: if you load 99 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 558 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 Terhi 620 is 2.58.

Compared with other similar sailboats it is more spacy than 69% 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 Terhi 620 is 41%.

This ballast ratio shows a righting moment that is higher than 66% of all similar sailboat designs. A righting moment (ability to resist heeling) just above average.

SA/D (Sail Area Displacement ratio)

SA/D (Sail Area Displacement ratio)
Indicates how fast the boat is in light wind:
- Cruising Boats have ratios 10-15
- Cruiser-Racers have ratios 16-20
- Racers have ratios above 20
- High-Performance Racers have ratios above 24
Sail-area/displacement ratio (SA/D ratio): 13.81

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	6.2 m	(20.3 feet)	10 mm	(3/8 inch)
Genoa sheet	6.2 m	(20.3 feet)	10 mm	(3/8 inch)
Mainsheet	15.5 m	(50.9 feet)	10 mm	(3/8 inch)
Spinnaker sheet	13.6 m	(44.8 feet)	10 mm	(3/8 inch)

Boat owner's ideas

This section shown boat owner's changes, improvements, etc. Here you might find inspiration for your boat.

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Finally

We are always looking for new photos. If you can contribute with photos for Terhi 620 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.