Deer Isle Koster (KDI)
Description
The Deer Isle Koster (KDI) is a versatile, lightweight sailing skiff designed by Bruce Elfstrom in 2009, inspired by traditional Scandinavian double-enders (Koster boats) but infused with modern catboat influences for family-friendly fun. Built primarily as a DIY kit by Chase Small Craft, it's optimized for youth sailors, beach launching, and "Swallows and Amazons"-style adventures—think swimming platforms, light-air performance, and easy reefing. With its wide beam, low freeboard, and balanced lug rig, the KDI excels as a row/sail hybrid for protected waters.
Construction Details
| Designer | Bruce Elfstrom |
|---|---|
| Builder | Chase Small Craft |
| Length | 14.000 ft |
| LOA | 14.000 ft |
| LWL | 12.500 ft |
| Beam | 5.830 ft |
| Displacement | 200 lb |
| Max Draft | 3.000 ft |
| Min Draft | 0.420 ft |
The standard boat dimensions
| i | 13 ft |
|---|---|
| j | 4.50 ft |
| p | - |
| e | - |
| p2 | - |
| e2 | - |
| i2 | - |
| j2 | - |
| I | J | P | E | P2 | E2 | I2 | J2 |
|---|---|---|---|---|---|---|---|
| 13 ft | 4.50 ft | - | - | - | - | - | - |
Documents
Blueprints
Sails
Deer Isle Koster (KDI) - JIBSAIL
| Luff | 10.44 ft - (3182 mm) |
|---|---|
| Foot | 4.1 ft - (1250 mm) |
| Leech | 8.81 ft - (2685 mm) |
| Percentage LP | * 75.33 % |
| Length Perpendicular | * 3.39 ft - (1033 mm) |
| Deck Angle | * 15.12 ° |
| Area | * 17.7 ft² |
| Comments | Standing Lug Sloop Rig, Jib |
| Edit in Calculator |
Deer Isle Koster (KDI) - JIBSAIL
| Luff | 11.21 ft - (3417 mm) |
|---|---|
| Foot | 3.7 ft - (1128 mm) |
| Leech | 9.66 ft - (2944 mm) |
| Percentage LP | * 68.44 % |
| Length Perpendicular | * 3.08 ft - (939 mm) |
| Deck Angle | * 14.59 ° |
| Area | * 17.26 ft² |
| Comments | Balanced Lug Sloop, Jib |
| Edit in Calculator |
Deer Isle Koster (KDI) - 4-SIDED SAIL
| Luff | 9.34 ft - (2847 mm) |
|---|---|
| Foot | 9.85 ft - (3002 mm) |
| Leech | 17.29 ft - (5270 mm) |
| Head | 10.13 ft - (3088 mm) |
| Diagonal | 12.92 ft - (3938 mm) |
| Tack Angle | 84.6 ° |
| Area | 110.82 ft² |
| Comments | Cat rig balanced lug sail. |
| Edit in Calculator |
Deer Isle Koster (KDI) - 4-SIDED SAIL
| Luff | 8.7 ft - (2652 mm) |
|---|---|
| Foot | 8.66 ft - (2640 mm) |
| Leech | 16.48 ft - (5023 mm) |
| Head | 9.48 ft - (2890 mm) |
| Diagonal | 11.67 ft - (3557 mm) |
| Tack Angle | 84.5 ° |
| Area | 91.63 ft² |
| Comments | Standing Lug sloop rig, lug main |
| Edit in Calculator |
Deer Isle Koster (KDI) - 4-SIDED SAIL
| Luff | 8.69 ft - (2649 mm) |
|---|---|
| Foot | 9.17 ft - (2795 mm) |
| Leech | 16.08 ft - (4901 mm) |
| Head | 9.42 ft - (2871 mm) |
| Diagonal | 12 ft - (3658 mm) |
| Tack Angle | 84.4 ° |
| Area | 95.8 ft² |
| Comments | Balanced Lug Sloop, Lug main |
| Edit in Calculator |
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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