Review of Thurø 33

Thurø 33 anno 1978. FRIGG - Faaborg

Basic specs.

The Thurø 33 is a sailboat designed by the Danish maritime architect Niels Roos together with Peter Roos also from Denmark in the mid seventies. Less than 100 boats have been produced. The Thurø 33 is built by the Danish yard A. Walsteds Baadeværft.

Looking for a new boat? Find a Thurø 33 or similar boat for sale

Hull

The hull is made of fibreglass. Generally, a hull made of fibreglass requires only a minimum of maintenance during the sailing season.

Interior

The interior is like many other boats made of mahogany.
The boat is equipped with 6 berths, a galley and toilet facility.

Rig

The boat equipped with a masthead rig. The advantage of a masthead rig is its simplicity and the fact that a given sail area - compared with a fractional rig - can be carried lower and thus with less heeling moment.

Keel

The Thurø 33 is equipped with a fin keel. The fin keel is the most common keel and provides splendid manoeuvrability. The downside is that it has less directional stability than a long 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 enter most marinas as the draft is just about 1.77 - 1.87 meter (5.81 - 6.11 ft) dependent on the load. See immersion rate below.

Engine

Thurø 33 is typically equipped with an inboard Bukh DV20 diesel engine at 20.0 hp (14 kW), which gives a max speed about 5.1 knots.

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 Thurø 33 is 1.78, indicating that this boat could - if evaluated by this formula alone - be accepted to participate in ocean races.

Theoretical Maximum Hull Speed

What is Theoretical Maximum Hull Speed?

The theoretical maximal speed of a displacement boat of this length is 7.0 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.

Immersion rate

The immersion rate is defined as the weight required to sink the boat a certain level. The immersion rate for Thurø 33 is about 168 kg/cm, alternatively 944 lbs/inch.
Meaning: if you load 168 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 944 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.

Motion Comfort Ratio

What is Motion Comfort Ratio (MCR)?

The Motion Comfort Ratio for Thurø 33 is 28.4.

Comparing this ratio with similar sailboats show that it is more comfortable than 69% of all similar sailboat designs. This comfort value is just above average.

L/B (Length Beam Ratio)

What is L/B (Length Beam Ratio)?

The l/b ratio for Thurø 33 is 3.30.

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.

Ballast Ratio

What is a Ballast Ratio?

The ballast ratio for Thurø 33 is 43%.

This ballast ratio shows a righting moment that is higher than 62% of all similar sailboat designs. A righting moment (ability to resist heeling) just above average.

D/L (Displacement Length Ratio)

What is Displacement Length Ratio?

The DL-ratio for Thurø 33 is 258 which categorizes this boat among 'light crusers & offshore racers'.

46% of all similar sailboat designs are categorized as heavier. A heavy displacement combined with smaller water plane area has lower acceleration and is more comfortable.

SA/D (Sail Area Displacement ratio)

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

The SA/D for Thurø 33 with ISO 8666 reference sail is 14.4, with a 135% genua the SA/D is 17.3.

The SA/D ratio indicates that it is faster than 18% of all similar sailboat designs in light wind.

Over- / underrigged

The Thurø 33 has more rig than 27% of all similar sailboats, which indicates that the boat is slightly underrigged.

RSP (Relative Speed Performance)

What is Relative Speed Performance?

The Relative Speed Performance for Thurø 33 is 46

The relative speed performance is 46 which means that a it is faster than 46% of all similar sailboat designs.

Maintenance

Bottom Paint

When buying anti-fouling bottom paint, it's nice to know how much to buy. The surface of the wet bottom is about 30m² (322 ft²).
Based on this, your favourite maritime shop can tell you the quantity you need.

Note: If you use a paint roller you will need more paint than if you use a paintbrush.

Rig

Dimensions of sail for masthead 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	29.6 m	(96.9 feet)	10 mm	(3/8 inch)
Jib/genoa halyard	29.6 m	(96.9 feet)	10 mm	(3/8 inch)
Spinnaker halyard	29.6 m	(96.9 feet)	10 mm	(3/8 inch)
Jib sheet	10.1 m	(33.0 feet)	12 mm	(1/2 inch)
Genoa sheet	10.1 m	(33.0 feet)	12 mm	(1/2 inch)
Mainsheet	25.1 m	(82.4 feet)	12 mm	(1/2 inch)
Spinnaker sheet	22.1 m	(72.5 feet)	12 mm	(1/2 inch)
Cunningham	3.2 m	(10.7 feet)	10 mm	(3/8 inch)
Kickingstrap	6.5 m	(21.3 feet)	10 mm	(3/8 inch)
Clew-outhaul	6.5 m	(21.3 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.

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 Thurø 33 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.