Review of IW 23

Basic specs.

The IW 23 aka Westkapp 23 is a small sailboat designed by the Swedish maritime architect Ivar Waldemar Åkesson in the mid sixties. A few hundred boats have been produced. The IW 23 is built by the Swedish yard IW-Varvet.

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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.

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

The IW 23 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 1.10 - 1.20 meter (3.61 - 3.91 ft) dependent on the load. See immersion rate below.

Engine

An outboard motor is often used on this boat. In that case the boat will typically require a power of 3 - 4 hp, alternatively 66 - 80 lbs thrust if you prefer an electrical motor. Electric outboards are becoming popular for sailboat owners who want clean instant power with less noise and no exhaust fumes.

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 IW 23 is 1.98, 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 5.9 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 IW 23 is about 90 kg/cm, alternatively 506 lbs/inch.
Meaning: if you load 90 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 506 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 IW 23 is 17.3.

Comparing this ratio with similar sailboats show that it is more comfortable than 69% 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 IW 23 is 3.04.

Compared with other similar sailboats it is slimmer than 69% of all other designs. It seems that the designer has chosen a slightly more speedy hull design.

Ballast Ratio

What is a Ballast Ratio?

The ballast ratio for IW 23 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 IW 23 is 193 which categorizes this boat among 'light racers'.

54% 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 IW 23 with ISO 8666 reference sail is 14.3, with a 135% genua the SA/D is 16.6.

The SA/D ratio indicates that it is faster than 21% of all similar sailboat designs in light wind.

Over- / underrigged

The IW 23 has more rig than 50% of all similar sailboats, which indicates that this rig is spot on average!

RSP (Relative Speed Performance)

What is Relative Speed Performance?

The Relative Speed Performance for IW 23 is 31

The relative speed performance is 31 which means that a it is faster than 31% 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 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

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	19.8 m	(65.0 feet)	8 mm	(5/16 inch)
Jib/genoa halyard	19.8 m	(65.0 feet)	8 mm	(5/16 inch)
Spinnaker halyard	19.8 m	(65.0 feet)	8 mm	(5/16 inch)
Jib sheet	6.8 m	(22.5 feet)	10 mm	(3/8 inch)
Genoa sheet	6.8 m	(22.5 feet)	10 mm	(3/8 inch)
Mainsheet	17.1 m	(56.2 feet)	10 mm	(3/8 inch)
Spinnaker sheet	15.1 m	(49.4 feet)	10 mm	(3/8 inch)
Cunningham	2.6 m	(8.5 feet)	8 mm	(5/16 inch)
Kickingstrap	5.2 m	(17.1 feet)	8 mm	(5/16 inch)
Clew-outhaul	5.2 m	(17.1 feet)	8 mm	(5/16 inch)

Boat owner's ideas

This section shown boat owner's changes, improvements, etc. Here you might find inspiration for your boat.

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Finally

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