Review of Lapworth 36

Basic specs.

The Lapworth 36 aka L 36 is a sailboat designed by the maritime architect C. William Lapworth in the early fifties. Less than 100 boats have been produced. The Lapworth 36 is built by the American yard Chapman & KA.

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Hull

The hull is made of wood.

Rig

The Lapworth 36 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

The Lapworth 36 has been built with different keel alternatives.

Unknown keel type

The boat can only enter major marinas as the draft is about 1.83 - 1.93 meter (6.00 - 6.30 ft) dependent on the load. See immersion rate below.

Fin keel

The Lapworth 36 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 boat can enter most marinas as the draft is just about 1.68 - 1.78 meter (5.51 - 5.81 ft) dependent on the load. See immersion rate below.

Engine

Lapworth 36 may be equipped with an inboard Universal Atomic 4 gasoline engine at 30 hp (22 kW). Calculated max speed is about 6.3 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 Lapworth 36 is 1.66, 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 7.1 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 Lapworth 36 is about 167 kg/cm, alternatively 938 lbs/inch.
Meaning: if you load 167 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 938 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 Lapworth 36 is 29.9.

Comparing this ratio with similar sailboats show that it is more comfortable than 66% 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 Lapworth 36 is 3.78.

Compared with other similar sailboats it is slimmer than 96% of all other designs. It seems that the designer has chosen a significantly more speedy hull design. This type of design is also referred to as 'needle'.

D/L (Displacement Length Ratio)

What is Displacement Length Ratio?

The DL-ratio for Lapworth 36 is 236 which categorizes this boat among 'light crusers & offshore racers'.

58% of all similar sailboat designs are categorized as heavier. A light displacement requires less sailarea and has higher accellerations.

SA/D (Sail Area Displacement ratio)

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

The SA/D for Lapworth 36 with ISO 8666 reference sail is 17.0, with a 135% genua the SA/D is 19.9.

The SA/D ratio indicates that it is faster than 54% of all similar sailboat designs in light wind.

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 31m² (333 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	28.4 m	(93.0 feet)	12 mm	(1/2 inch)
Jib/genoa halyard	28.4 m	(93.0 feet)	12 mm	(1/2 inch)
Spinnaker halyard	28.4 m	(93.0 feet)	12 mm	(1/2 inch)
Jib sheet	11.0 m	(36.0 feet)	14 mm	(0.55 inch)
Genoa sheet	11.0 m	(36.0 feet)	14 mm	(0.55 inch)
Mainsheet	27.4 m	(90.0 feet)	14 mm	(0.55 inch)
Spinnaker sheet	24.1 m	(79.2 feet)	14 mm	(0.55 inch)
Cunningham	4.9 m	(16.0 feet)	12 mm	(1/2 inch)
Kickingstrap	9.8 m	(32.0 feet)	12 mm	(1/2 inch)
Clew-outhaul	9.8 m	(32.0 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.

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Finally

We are always looking for new photos. If you can contribute with photos for Lapworth 36 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.