Review of IOD

Basic specs.

The IOD is a sailboat designed by the Norwegian maritime architect Bjarne Aas in the mid thirties. A few hundred boats have been produced. The IOD is built by the Norwegian yard Bjarne Aas Båtbyggeri.

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Rig

The boat equipped with a fractional rig. A fractional rig has smaller headsails which make tacking easier, which is an advantage for cruisers and racers, of course. The downside is that having the wind from behind often requires a genaker or a spinnaker for optimal speed.

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 IOD is 1.41, 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 6.2 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 IOD is about 90 kg/cm, alternatively 504 lbs/inch.
Meaning: if you load 90 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 504 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 IOD is 34.0.

Comparing this ratio with similar sailboats show that it is more comfortable than 90% 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 IOD is 4.94.

Compared with other similar sailboats it is slimmer than 100% 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 IOD is 320 which categorizes this boat among 'medium weight cruisers'.

21% 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.

RSP (Relative Speed Performance)

What is Relative Speed Performance?

The Relative Speed Performance for IOD is 27

The relative speed performance is 27 which means that a it is faster than 27% of all similar sailboat designs.

Maintenance

Rig

Dimensions of sail for fractional 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	31.1 m	(101.9 feet)	10 mm	(3/8 inch)
Jib/genoa halyard	31.1 m	(101.9 feet)	10 mm	(3/8 inch)
Spinnaker halyard	31.1 m	(101.9 feet)	10 mm	(3/8 inch)
Jib sheet	10.2 m	(33.4 feet)	12 mm	(1/2 inch)
Genoa sheet	10.2 m	(33.4 feet)	12 mm	(1/2 inch)
Mainsheet	25.4 m	(83.5 feet)	12 mm	(1/2 inch)
Spinnaker sheet	22.4 m	(73.5 feet)	12 mm	(1/2 inch)
Cunningham	4.9 m	(16.1 feet)	10 mm	(3/8 inch)
Kickingstrap	9.8 m	(32.2 feet)	10 mm	(3/8 inch)
Clew-outhaul	9.8 m	(32.2 feet)	10 mm	(3/8 inch)

Boat owner's ideas

This section is reserved boat owner's changes, 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 IOD 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.