ALPA 21
Specifications
Hull
| LOA | 21.25 ft |
| LWL | 18.6 ft |
| Beam | 8.16 ft |
| Draft | 4 ft |
| Displacement | 2,868 lb |
| Ballast | 799.9 lb |
| Hull speed1.34·√LWL | 5.8 kn |
Rig & Sails
| Iforetriangle height | 30 ft |
| Jforetriangle base | 8.55 ft |
| Pmainsail luff | 26 ft |
| Emainsail foot | 9 ft |
| FLforestay | 8.6 ft |
| Mainsail | 254.6 sq ft |
| Jib (100%) | 128.3 sq ft |
| Spinnaker | 218 sq ft |
About the ALPA 21
The Alpa 21 is a compact, lightweight masthead sloop designed by Sparkman & Stephens and built by Alpa in Italy, with production records indicating a single year of construction in 1976. With a displacement of 2868.0 lb and a beam of 8.16 ft, this vessel represents a classic, performance-oriented day sailor or coastal cruiser from the mid-1970s.
- Best for:
- This boat is best suited for coastal cruising, day sailing, and weekend trips where ease of handling and storage are priorities, rather than extended offshore passages. Its light displacement and modest beam make it ideal for single-handers or couples seeking a manageable, classic S&S design.
- Bluewater capability:
- With a low displacement of 2868.0 lb, a capsize ratio of 2.3, and a comfort ratio of 13.95, the Alpa 21 is not designed for serious bluewater cruising but is capable of protected coastal and bay sailing.
- Comparables:
- Comparable boats include the Pearson 20 and the O'Day 22, which share similar dimensions, light displacement characteristics, and the same era of production. These vessels offer similar roles as affordable, easy-to-trailer coastal cruisers with comparable beam and draft profiles.
Performance
ORC Performance Data(1 certificate)
Measured performance data from ORC (Offshore Racing Congress) certificates.
Polar Diagram
Boat speed (kn) vs. true wind angle. Source: ORC
Racing Ratings
Triple Number
ORC Measured
Sail Areas (ORC)
Speed Table (kn)
| TWA \ TWS | 6 | 8 | 10 | 12 | 14 | 16 | 20 | 24 |
|---|---|---|---|---|---|---|---|---|
| 52° | 4.1 | 4.8 | 5.3 | 5.5 | 5.6 | 5.6 | 5.7 | 5.5 |
| 60° | 4.3 | 5.0 | 5.4 | 5.6 | 5.8 | 5.8 | 5.9 | 5.8 |
| 75° | 4.5 | 5.2 | 5.5 | 5.8 | 6.0 | 6.1 | 6.2 | 6.3 |
| 90° | 4.4 | 5.2 | 5.7 | 5.9 | 6.1 | 6.2 | 6.5 | 6.7 |
| 110° | 4.5 | 5.3 | 5.8 | 6.1 | 6.4 | 6.7 | 7.2 | 7.5 |
| 120° | 4.3 | 5.2 | 5.7 | 6.0 | 6.4 | 6.7 | 7.6 | 8.3 |
| 135° | 3.8 | 4.8 | 5.5 | 5.8 | 6.2 | 6.5 | 7.4 | 9.0 |
| 150° | 3.3 | 4.2 | 5.0 | 5.5 | 5.9 | 6.2 | 6.9 | 7.9 |
| Beat VMG | 2.6 | 3.2 | 3.6 | 3.8 | 3.9 | 4.0 | 3.9 | 3.6 |
| Run VMG | 2.9 | 3.7 | 4.4 | 5.0 | 5.5 | 5.8 | 6.4 | 7.1 |
Pricing
We don't have market pricing data for the ALPA 21 yet. If you own one, help other buyers — what did you pay for it? Reports build a community price estimate over time.
Estimated Cost of Ownership
Based on 21.25ft LOA. Actual costs vary by condition, usage, and local rates.
Known Issues & Pre-Purchase Inspection
We don't have enough data on the ALPA 21yet to publish model-specific findings we'd stand behind — but here's a free general inspection checklist, built from our research into what actually goes wrong on boats of this kind.
Drawn from 7,029 documented issues across 2,391 models, ordered so the areas that most often turn up problems come first.
Own a ALPA 21? Reports from owners are what turn this into a model-specific checklist — and they're the reason the boats above it have one.
Similar Sailboats
Which engine powers your ALPA 21?
We haven't confirmed the engine for this model yet. If you own or know one, tell us — as owners report in, we build an accurate picture over time.
Already know your engine? Search all engines → to find its exact parts.
Used sails that fit the ALPA 21
Checking eBay for sails sized to this boat's rig…