Kaulua 31
Description
The Kaulua 31 is a rare American fiberglass catamaran (open-deck or semi-open design) built by Harstil Industries Inc. (a small Michigan-based yard) from the late 1970s through the 1980s. It was produced in limited numbers (likely dozens of hulls, not a high-volume run), with examples still occasionally discussed or converted in owner communities (e.g., Facebook groups for multihulls or solar/electric refits). The design emphasizes lightweight, slender hulls for speed and efficiency, similar in appearance to the Stiletto 30 but without the same widespread popularity or class structure—often described as a "slippery" performer suitable for daysailing, coastal cruising, or racing in protected waters, with good light-air capability from a generous sail plan. Construction is fiberglass for durability and low maintenance, featuring twin hulls (beam ~14 ft in some reports), shallow draft for trailering/beaching, and minimal accommodations (open deck layout with basic cuddy or shelter options in some builds).
Construction Details
| Designer | Unknown |
|---|---|
| Builder | Harstil Industries Inc. |
| Length | 31.000 ft |
| LOA | 31.000 ft |
| Year Built | 1979 |
The standard boat dimensions
| i | 38.10 ft |
|---|---|
| j | 11.75 ft |
| p | 33.50 ft |
| e | 12 ft |
| p2 | - |
| e2 | - |
| i2 | - |
| j2 | - |
| I | J | P | E | P2 | E2 | I2 | J2 |
|---|---|---|---|---|---|---|---|
| 38.10 ft | 11.75 ft | 33.50 ft | 12 ft | - | - | - | - |
Sails
Kaulua 31 - MAINSAIL
| Luff | * 33.5 ft - (10211 mm) |
|---|---|
| Foot | * 12 ft - (3658 mm) |
| Leech | * 35.04 ft - (10680 mm) |
| Tack Angle | * 88.01 ° |
| Diagonal | * 35.19 ft - (10726 mm) |
| Head (inches) | * 5.25 in - (133 mm) |
| Area | 200.77 ft² |
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Kaulua 31 - JIBSAIL
| Luff | * 31.9 ft - (9723 mm) |
|---|---|
| Foot | * 15.47 ft - (4715 mm) |
| Leech | * 27.86 ft - (8492 mm) |
| Percentage LP | * 115 % |
| Length Perpendicular | * 13.51 ft - (4118 mm) |
| Deck Angle | * 12 ° |
| Area | 215.5 ft² |
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Kaulua 31 - GENOA
| Luff | * 37.88 ft - (11546 mm) |
|---|---|
| Foot | * 18.9 ft - (5761 mm) |
| Leech | * 35.72 ft - (10887 mm) |
| Percentage LP | * 150 % |
| Length Perpendicular | * 17.63 ft - (5374 mm) |
| Deck Angle | * 4 ° |
| Area | 333.9 ft² |
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Kaulua 31 - SPINNAKER
| Stays | * 37.88 ft - (11546 mm) |
|---|---|
| MidGirth | * 21.15 ft - (6447 mm) |
| Foot | * 21.15 ft - (6447 mm) |
| Perc LP | * 180 % |
| Area | 680.99 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.
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