Review of Irwin 37 Mk I
Basic specs.
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The hull is made of fibreglass. Generally, a hull made of fibreglass requires only a minimum of maintenance during the sailing season.
The boat is equipped with 189.0 liter fresh water capacity.
The Irwin 37 Mk I 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.
The Irwin 37 Mk I has been built with different keel alternatives.
Fin keel
One option is 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.
Fin keel
Another option is 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.
Irwin 37 Mk I can enter even shallow marinas as the draft is just about 1.22 - 1.32 meter (4.00 - 4.30 ft) dependent on the load. See immersion rate below.
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.
What is Capsize Screening Formula (CSF)?
The capsize screening value for Irwin 37 Mk I is 1.88, 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 7.3 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 Irwin 37 Mk I is about 218 kg/cm, alternatively 1220 lbs/inch.
Meaning: if you load 218 kg cargo on the boat then it will sink 1 cm.
Alternatively, if you load 1220 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.
What is Motion Comfort Ratio (MCR)?
The Motion Comfort Ratio for Irwin 37 Mk I is 27.9.
What is L/B (Length Beam Ratio)?
The l/b ratio for Irwin 37 Mk I is 3.17.
The ballast ratio for Irwin 37 Mk I is 37%.
What is Displacement Length Ratio?
The DL-ratio for Irwin 37 Mk I is 254 which categorizes this boat among 'light crusers & offshore racers'.
What is SA/D (Sail Area Displacement ratio)?
The SA/D for Irwin 37 Mk I with ISO 8666 reference sail is 16.2, with a 135% genua the SA/D is 19.7.
Maintenance
When buying anti-fouling bottom paint, it's nice to know how much to buy.
The surface of the wet bottom is about 36m2 (387 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.
| Usage | Length | Diameter | ||
| Mainsail halyard | 33.7 m | (110.5 feet) | 12 mm | (1/2 inch) |
| Jib/genoa halyard | 33.7 m | (110.5 feet) | 12 mm | (1/2 inch) |
| Spinnaker halyard | 33.7 m | (110.5 feet) | 12 mm | (1/2 inch) |
| Jib sheet | 11.3 m | (37.0 feet) | 14 mm | (0.55 inch) |
| Genoa sheet | 11.3 m | (37.0 feet) | 14 mm | (0.55 inch) |
| Mainsheet | 28.2 m | (92.5 feet) | 14 mm | (0.55 inch) |
| Spinnaker sheet | 24.8 m | (81.4 feet) | 14 mm | (0.55 inch) |
| Cunningham | 3.6 m | (11.8 feet) | 12 mm | (1/2 inch) |
| Kickingstrap | 7.2 m | (23.6 feet) | 12 mm | (1/2 inch) |
| Clew-outhaul | 7.2 m | (23.6 feet) | 12 mm | (1/2 inch) |
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