Review of LM 81

Both the hull and the deck 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.
The deck is a double deck which improves the indoor climate.

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

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.

The LM 81 is equipped with a fin keel. A boat with a fin keel is more manoeuvrable but has less directional stability than a similar boat with a long keel.

The keel is made of iron. Many people prefer lead keel in favour of iron. The main argument is that lead is much heavier than iron and a lead keel can therefore be made smaller which again result in less wet surface, i.e. less drag. In fact iron is quite heavy, just 30% less heavy than lead, so the advantage of a lead keel is often overstated. As the surface of a fin type keel is just a fraction of the total wet surface, the difference between an iron keel and a lead keel can in reality be ignored for cruising yachts.

The boat can enter even shallow marinas as the draft is just about 1.35 - 1.45 meter (4.43 - 4.73 ft) dependent on the load. See immersion rate below.

LM 81 is typically equipped with an inboard Bukh DV8 diesel engine at 8.0 hp (5 kW), which gives a max speed about 3.6 knots.

The transmission is a saildrive.

The fuel tank which is made of fibreglass has a capacity of 70.0 liters (18 US gallons, 15 imperial gallons).

What is Capsize Screening Formula (CSF)?

The capsize screening value for LM 81 is 1.94, indicating that this boat could - if evaluated by this formula alone - be accepted to participate in ocean races.

What is Theoretical Maximum Hull Speed?

The theoretical maximal speed of a displacement boat of this length is 6.3 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.

The immersion rate is defined as the weight required to sink the boat a certain level. The immersion rate for LM 81 is about 132 kg/cm, alternatively 739 lbs/inch.
Meaning: if you load 132 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 739 lbs cargo on the boat it will sink 1 inch.

What is Motion Comfort Ratio (MCR)?

The Motion Comfort Ratio for LM 81 is 24.3.

Comparing this ratio with similar sailboats show that it is more comfortable than 76% of all similar sailboat designs. This is a comfort value significantly above average.

What is L/B (Length Beam Ratio)?

The l/b ratio for LM 81 is 2.79.

Compared with other similar sailboats it is more spacy than 79% of all other designs. It seems that the designer has chosen a significantly more spacy hull design.

What is a Ballast Ratio?

The ballast ratio for LM 81 is 41%.

This ballast ratio shows a righting moment that is higher than 54% of all similar sailboat designs. A righting moment (ability to resist heeling) just above average.

What is Displacement Length Ratio?

The DL-ratio for LM 81 is 301 which categorizes this boat among 'medium weight cruisers'.

24% 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.

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

The SA/D for LM 81 with ISO 8666 reference sail is 11.7, with a 135% genua the SA/D is 13.8.

The SA/D ratio indicates that it is faster than 8% of all similar sailboat designs in light wind.
Don't panic! It is expected that motor sailers has a low SA/D value as this is the natural consequence of the design combining sailing and motor boat characteristics.

The LM 81 has more rig than 24% of all similar sailboats, which indicates that the boat is significantly underrigged.
Don't panic! It is expected that motor sailers are underrigged as this is the natural consequence of the design combining sailing and motor boat characteristics.

What is Relative Speed Performance?

The Relative Speed Performance for LM 81 is 21

The relative speed performance is 21 which means that a it is faster than 21% 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.

When buying anti-fouling bottom paint, it's nice to know how much to buy. The surface of the wet bottom is about 22m² (236 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.

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.

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.

We are always looking for new photos. If you can contribute with photos for LM 81 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.

[Ref 1]: ISO 8666 Small craft — Principal data.
[Ref 3]: ISO 12215-5 Small craft — Hull construction and scantlings.