Review of Castle 650

Basic specs.

The Castle 650 is a small sailboat designed by the maritime architect Steven Douglas in the early eighties. A few hundred boats have been produced. The Castle 650 is built by the Australian yard Yacht Works Inc.

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Hull

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.

Rig

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.

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.

The boat can sail close to the beach as the draft is just 0.30 - 0.40 meter (0.98 - 1.28 ft) dependent of the load. See immersion rate below.

Trailer

Castle 650 on trailer.

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 Castle 650 is 2.67, 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 Castle 650 is about 106 kg/cm, alternatively 595 lbs/inch.
Meaning: if you load 106 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 595 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 Castle 650 is 2.71.

Compared with other similar sailboats it is more spacy than 62% 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 Castle 650 is 33%.

This ballast ratio shows a righting moment that is higher than 31% of all similar sailboat designs. A righting moment (ability to resist heeling) just below average.

SA/D (Sail Area Displacement ratio)

What is SA/D (Sail Area Displacement ratio)?

The SA/D for Castle 650 with ISO 8666 reference sail is 27.1, with a 135% genua the SA/D is 30.1.

The SA/D ratio indicates that it is faster than 98% of all similar sailboat designs in light wind.

Maintenance

Rig

Dimensions of sail for fractional rig.

Are your sails worn out? You might find your next sail here: Sails for Sale

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
Mainsail halyard	20.7 m	(68.0 feet)	8 mm	(5/16 inch)
Jib/genoa halyard	20.7 m	(68.0 feet)	8 mm	(5/16 inch)
Spinnaker halyard	20.7 m	(68.0 feet)	8 mm	(5/16 inch)
Jib sheet	6.6 m	(21.5 feet)	10 mm	(3/8 inch)
Genoa sheet	6.6 m	(21.5 feet)	10 mm	(3/8 inch)
Mainsheet	16.4 m	(53.8 feet)	10 mm	(3/8 inch)
Spinnaker sheet	14.4 m	(47.3 feet)	10 mm	(3/8 inch)
Cunningham	3.9 m	(12.8 feet)	8 mm	(5/16 inch)
Kickingstrap	7.8 m	(25.6 feet)	8 mm	(5/16 inch)
Clew-outhaul	7.8 m	(25.6 feet)	8 mm	(5/16 inch)

Boat owner's ideas

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

Do you have changes/improvements you would like to share? Upload a photo and describe what to look for.

Finally

We are always looking for new photos. If you can contribute with photos for Castle 650 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.