Irwin 37 MK III (Sloop)
Description
The Irwin 37 Mk III Sloop (1976–1979) is the single-masted version of the popular Mk III center-cockpit series, combining the same enormously roomy interior as the well-known Mk III Ketch with a taller, more efficient sloop rig for noticeably better upwind performance and lighter-air speed. It shares the identical hull and deck molding: 37′ LOA, 11′6″ beam, ~20,000 lb displacement, 8,000 lb ballast, and the choice of a 5′4″ shoal scheel keel or optional 6′ fin. The rig, however, carries a high-aspect mainsail and large overlapping genoa on a taller single-spreader masthead spar (I ~47′, J ~15′), giving it a respectable SA/D around 17–18—considerably more drive than the split ketch rig. Below, it retains the signature Irwin 37 layout that still impresses today: private aft owner’s stateroom with en-suite head and real standing room, walk-through passageway, huge U-shaped galley to port, nav station opposite, spacious saloon with 6′6″+ headroom, and a big forward V-berth with second head—easily the most interior volume ever offered in a production 37-footer of the 1970s.
The standard boat dimensions
| i | 42 ft |
|---|---|
| j | 17.50 ft |
| p | 35.50 ft |
| e | 14.50 ft |
| p2 | - |
| e2 | - |
| i2 | - |
| j2 | - |
| I | J | P | E | P2 | E2 | I2 | J2 |
|---|---|---|---|---|---|---|---|
| 42 ft | 17.50 ft | 35.50 ft | 14.50 ft | - | - | - | - |
Sails
Irwin 37 MK III (Sloop) - MAINSAIL
| Luff | * 35.5 ft - (10820 mm) |
|---|---|
| Foot | * 14.5 ft - (4420 mm) |
| Leech | * 37.6 ft - (11460 mm) |
| Tack Angle | * 88 ° |
| Diagonal | * 37.88 ft - (11546 mm) |
| Head (inches) | * 6 in - (152 mm) |
| Area | * 265.04 ft² |
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Irwin 37 MK III (Sloop) - JIBSAIL
| Luff | * 36.4 ft - (11095 mm) |
|---|---|
| Foot | * 24.45 ft - (7452 mm) |
| Leech | * 30.19 ft - (9202 mm) |
| Percentage LP | * 114.97 % |
| Length Perpendicular | * 20.12 ft - (6133 mm) |
| Deck Angle | * 12 ° |
| Area | * 366.19 ft² |
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Irwin 37 MK III (Sloop) - JIBSAIL
| Luff | 41.75 ft - (12725 mm) |
|---|---|
| Foot | 24 ft - (7315 mm) |
| Leech | 33.5 ft - (10211 mm) |
| Percentage LP | * 110 % |
| Length Perpendicular | * 19.25 ft - (5867 mm) |
| Deck Angle | * 14.05 ° |
| Area | * 401.84 ft² |
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Irwin 37 MK III (Sloop) - GENOA
| Luff | * 43.22 ft - (13173 mm) |
|---|---|
| Foot | * 29.36 ft - (8949 mm) |
| Leech | * 39.92 ft - (12168 mm) |
| Percentage LP | * 150 % |
| Length Perpendicular | * 26.25 ft - (8001 mm) |
| Deck Angle | * 3.98 ° |
| Area | * 567.31 ft² |
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Irwin 37 MK III (Sloop) - GENOA
| Luff | 42 ft - (12802 mm) |
|---|---|
| Foot | 26.5 ft - (8077 mm) |
| Leech | 36.5 ft - (11125 mm) |
| Percentage LP | * 130.29 % |
| Length Perpendicular | * 22.8 ft - (6949 mm) |
| Deck Angle | * 8.01 ° |
| Area | * 478.87 ft² |
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Irwin 37 MK III (Sloop) - ASYMMETRICAL
| Luff | 45 ft - (13716 mm) |
|---|---|
| Foot | 29 ft - (8839 mm) |
| Leech | 41 ft - (12497 mm) |
| Perc LP | * 165 % |
| Area | * 979 ft² |
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Irwin 37 MK III (Sloop) - STORMJIB
| Luff | 23.5 ft - (7163 mm) |
|---|---|
| Foot | 13.5 ft - (4115 mm) |
| Leech | 18 ft - (5486 mm) |
| Perc LP | * 58.8 % |
| Length Perp | * 10.29 ft - (3136 mm) |
| Deck Angle | * 17.69 ° |
| Area | * 120.95 ft² |
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Disclaimer. Boats are not all the same -- even when produced in the same factory of the same model. Sailrite does its best to publish accurate dimensions, but we often find it worthwhile to have our customers measure their boats carefully before we produce kits for them. You should take the same precautions, especially when the data is not from Sailrite. The information on this site is not guaranteed to be accurate. Sailrite offers this content as a service to our community, but takes no responsibility for the reliability of the data provided.