Review of LM 23

LM 23 anno 1975. lm 23 med mast (8 m)sejl storsejl lm 24

Basic specs.

The LM 23 aka LM 23 MS is a motorsailer designed by the Danish maritime architect Palle Mortensen in the late sixties. Several hundred boats have been produced. The LM 23 is built by the Danish yard LM Glasfiber A/S.

Looking for a new boat? Find a LM 23 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. And outside the sailing season, just bottom cleaning and perhaps anti-fouling painting once a year - a few hours of work, that's all.

Interior

Interior of LM 23 anno 1973.

The interior is like many other boats made of mahogany.
The boat is equipped with one cabin, 2 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

Keel of LM 23 anno 1971.

The LM 23 is equipped with a long keel. A long keel provide a better directional stability than a similar boat with a fin keel; on the other hand, better directional stability means also that the boat is more difficult to handle in a harbour with less space.

The boat can enter even shallow marinas as the draft is just about 0.70 - 0.80 meter (2.30 - 2.60 ft) dependent on the load. See immersion rate below.

Engine

LM 23 is typically equipped with an inboard Bukh diesel engine at 20.0 hp (14 kW), which gives a max speed about 6.4 knots.

The transmission is a shaft drive. A shaft drive will in the long run require less maintenence than other types of drive e.g. a sail drive.

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 LM 23 is 1.81, 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 6.1 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 LM 23 is about 102 kg/cm, alternatively 572 lbs/inch.
Meaning: if you load 102 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 572 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 LM 23 is 24.8.

Comparing this ratio with similar sailboats show that it is more comfortable than 96% of all similar sailboat designs. This is a comfort value significantly above average.

L/B (Length Beam Ratio)

What is L/B (Length Beam Ratio)?

The l/b ratio for LM 23 is 2.92.

Compared with other similar sailboats it is more spacy than 50% of all other designs. It seems that the designer has chosen an average hull design.

Ballast Ratio

What is a Ballast Ratio?

The ballast ratio for LM 23 is 36%.

This ballast ratio shows a righting moment that is higher than 38% of all similar sailboat designs. A righting moment (ability to resist heeling) just below average.

D/L (Displacement Length Ratio)

What is Displacement Length Ratio?

The DL-ratio for LM 23 is 285 which categorizes this boat among 'medium weight cruisers'.

15% 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)

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): 12.67

RSP (Relative Speed Performance)

What is Relative Speed Performance?

The Relative Speed Performance for LM 23 is 1

The relative speed performance is 1 which means that a it is faster than 1% of all similar sailboat designs. As this boat is a motor sailer, it is expected that the performance of a motor sailer for sail alone is lower than a dedicated sailboat.

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 15m² (161 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

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	7.1 m	(23.4 feet)	10 mm	(3/8 inch)
Genoa sheet	7.1 m	(23.4 feet)	10 mm	(3/8 inch)
Mainsheet	17.8 m	(58.4 feet)	10 mm	(3/8 inch)
Spinnaker sheet	15.7 m	(51.4 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 LM 23 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.