The Alpa 21 is a 21.25ft masthead sloop designed by Sparkman & Stephens and built in fiberglass by Alpa Yachts (ITA) since 1976.
The Alpa 21 is a light sailboat which is a good performer. It is stable / stiff and has a low righting capability if capsized. It is best suited as a day-boat.
Main features
| Model | Alpa 21 | ||
| Length | 21.25 ft | ||
| Beam | 8.16 ft | ||
| Draft | 4 ft | ||
| Country | Italy (Europe) | ||
| Estimated price | $ 0 | ?? | 
Ratios
| Sail area / displ. | 19.49 | ||
| Ballast / displ. | 27.89 % | ||
| Displ. / length | 198.97 | ||
| Comfort ratio | 13.95 | ||
| Capsize | 2.30 | 
Hull
| Hull type | Monohull fin keel with transom hung rudder | ||
| Construction | Fiberglass | ||
| Waterline length | 18.60 ft | ||
| Maximum draft | 4 ft | ||
| Displacement | 2868 lbs | ||
| Ballast | 800 lbs | ||
| Hull speed | 5.78 knots | 
Rigging
| Rigging | Masthead Sloop | ||
| Sail area (100%) | 245 sq.ft | ||
| Air draft | 0 ft | ?? | |
| Sail area fore | 128.25 sq.ft | ||
| Sail area main | 117 sq.ft | ||
| I | 30 ft | ||
| J | 8.55 ft | ||
| P | 26 ft | ||
| E | 9 ft | 
Engine
| Nb engines | 1 | ||
| Total power | 0 HP | ||
| Fuel capacity | 0 gals | 
Accommodations
| Water capacity | 0 gals | ||
| Headroom | 0 ft | ||
| Nb of cabins | 0 | ||
| Nb of berths | 0 | ||
| Nb heads | 0 | 
Builder data
| Builder | Alpa Yachts (ITA) | ||
| Designer | Sparkman & Stephens | ||
| First built | 1976 | ||
| Last built | 0 | ?? | |
| Number built | 0 | ?? | 
 
                         
                                                     
                                         
                                         
                                         
                                         
                                         
                                        