Review of Murena

Murena anno 1974.

Basic specs.

The Murena is a sailboat designed by the Swedish maritime architect Håkan Södergren in the early seventies. Several hundred boats have been produced. The Murena is built by the Swedish yard Boatsman Sunsail.

Looking for a new boat? Find a Murena or similar boat for sale

Interior

The boat is equipped with 5 berths, a galley and toilet facility.

Rig

The Murena is 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

Unknown keel type

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 1.50 - 1.60 meter (4.92 - 5.22 ft) dependent on the load. See immersion rate below.

Engine

Murena may be equipped with an inboard Bukh DV10M diesel engine at 12 hp (8 kW). Calculated max speed is about 4.6 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 Murena is 2.18, indicating that this boat would not 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 6.4 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 Murena is about 149 kg/cm, alternatively 835 lbs/inch.
Meaning: if you load 149 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 835 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 Murena is 19.1.

Comparing this ratio with similar sailboats show that it is more comfortable than 27% of all similar sailboat designs. This comfort value is just below average.

L/B (Length Beam Ratio)

What is L/B (Length Beam Ratio)?

The l/b ratio for Murena is 2.85.

Compared with other similar sailboats it is more spacy than 76% of all other designs. It seems that the designer has chosen a significantly more spacy hull design.

Ballast Ratio

What is a Ballast Ratio?

The ballast ratio for Murena is 36%.

This ballast ratio shows a righting moment that is higher than 24% of all similar sailboat designs. A righting moment (ability to resist heeling) significantly below average.

D/L (Displacement Length Ratio)

What is Displacement Length Ratio?

The DL-ratio for Murena is 260 which categorizes this boat among 'light crusers & offshore racers'.

50% of all similar sailboat designs are categorized as heavier. This boat has a precise average ratio between displacement and length!

SA/D (Sail Area Displacement ratio)

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

The SA/D for Murena with ISO 8666 reference sail is 15.6, with a 135% genua the SA/D is 18.6.

The SA/D ratio indicates that it is faster than 42% of all similar sailboat designs in light wind.

Over- / underrigged

The Murena has more rig than 86% of all similar sailboats, which indicates that the boat is significantly overrigged.

RSP (Relative Speed Performance)

What is Relative Speed Performance?

The Relative Speed Performance for Murena is 58

The relative speed performance is 58 which means that a it is faster than 58% 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 25m² (269 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	24.9 m	(81.8 feet)	10 mm	(3/8 inch)
Jib/genoa halyard	24.9 m	(81.8 feet)	10 mm	(3/8 inch)
Spinnaker halyard	24.9 m	(81.8 feet)	10 mm	(3/8 inch)
Jib sheet	9.1 m	(29.7 feet)	12 mm	(1/2 inch)
Genoa sheet	9.1 m	(29.7 feet)	12 mm	(1/2 inch)
Mainsheet	22.7 m	(74.3 feet)	12 mm	(1/2 inch)
Spinnaker sheet	19.9 m	(65.4 feet)	12 mm	(1/2 inch)
Cunningham	3.0 m	(10.0 feet)	10 mm	(3/8 inch)
Kickingstrap	6.1 m	(20.0 feet)	10 mm	(3/8 inch)
Clew-outhaul	6.1 m	(20.0 feet)	10 mm	(3/8 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 Murena 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.