Review of Sirena 40

Sirena 40. Sirena 40 WH. WH = Weehlhouse or Deckssaloon

Basic specs.

The Sirena 40 is a large sailboat designed by the British maritime architect David Pedrick in the late eighties. Only a few boats have been produced. The Sirena 40 is built by the Finnish yard Lito Marin.

Looking for a new boat? Find a Sirena 40 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 boat is equipped with 3 cabins, 6 berths, a galley, 300.0 liter fresh water capacity and 90.0 liter waste water capacity.

Rig

The Sirena 40 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

Keel of Sirena 40. Sirena 40 WH. WH = Wheelhouse

The Sirena 40 has been built with different keel alternatives.

Fin keel

One option is 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 boat can only enter major marinas as the draft is about 1.80 - 1.90 meter (5.91 - 6.21 ft) dependent on the load. See immersion rate below.

Fin keel

Another option is 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.

Sirena 40 can only enter major marinas as the draft is about 2.10 - 2.20 meter (6.89 - 7.19 ft) dependent on the load. See immersion rate below.

Engine

The boat may be equipped with an inboard Volvo Penta 2003 T diesel engine at 43 hp (32 kW). Calculated max speed is about 6.1 knots

The transmission is a saildrive.

The fuel tank has a capacity of 90.0 liters (23 US gallons, 19 imperial gallons).

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 Sirena 40 is 1.82, 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 7.5 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 Sirena 40 is about 238 kg/cm, alternatively 1336 lbs/inch.
Meaning: if you load 238 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 1336 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 Sirena 40 is 31.8.

Comparing this ratio with similar sailboats show that it is more comfortable than 62% 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 Sirena 40 is 3.25.

Compared with other similar sailboats it is more spacy than 54% 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 Sirena 40 is 42%.

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.

D/L (Displacement Length Ratio)

What is Displacement Length Ratio?

The DL-ratio for Sirena 40 is 292 which categorizes this boat among 'medium weight cruisers'.

31% 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 Sirena 40 with ISO 8666 reference sail is 18.4, with a 135% genua the SA/D is 21.9.

The SA/D ratio indicates that it is faster than 62% of all similar sailboat designs in light wind.

Over- / underrigged

The Sirena 40 has more rig than 69% of all similar sailboats, which indicates that the boat is slightly overrigged.

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 40m² (430 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 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	40.0 m	(131.2 feet)	12 mm	(1/2 inch)
Jib/genoa halyard	40.0 m	(131.2 feet)	12 mm	(1/2 inch)
Spinnaker halyard	40.0 m	(131.2 feet)	12 mm	(1/2 inch)
Jib sheet	12.2 m	(40.0 feet)	14 mm	(0.55 inch)
Genoa sheet	12.2 m	(40.0 feet)	14 mm	(0.55 inch)
Mainsheet	30.5 m	(100.1 feet)	14 mm	(0.55 inch)
Spinnaker sheet	26.8 m	(88.1 feet)	14 mm	(0.55 inch)
Cunningham	4.6 m	(15.1 feet)	12 mm	(1/2 inch)
Kickingstrap	9.2 m	(30.2 feet)	12 mm	(1/2 inch)
Clew-outhaul	9.2 m	(30.2 feet)	12 mm	(1/2 inch)

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.

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

Finally

We are always looking for new photos. If you can contribute with photos for Sirena 40 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.