Originally a single-seat, high-wing monoplane, it was developed into a two-seat biplane for production in kit form as the SMAN Pétrel.
The Hydroplum's Hirth engine is mounted in pusher configuration on the pylon with its propeller shaft in the plane of the wing.
At the rear of the hull a boom projects aft and slightly upwards, bearing the swept fin and rudder and low set, rectangular tailplane and one piece elevator.
[3] Soon after the Paris show Tisserand began modifying the design to make it suitable for homebuilding from commercially produced kits, deciding that it should become a two seater with glass fibre fuselage and wings, though the empennage remained wood.
The greatest change was that the Hydroplum II was a single bay biplane rather than a monoplane, a revision made to simplify transport by shortening the span.
The fuselage was widened to accommodate two side-by-side in an open cockpit and refined aft, under a revised pylon which now rose from a rounded, raised upper fairing.
[3] The production, kit built, Hydroplum II was introduced in September 1987 under that name[4] but was soon marketed as the Société Morbihannaise d'Aéro Navigation SMAN Pétrel.
These differed from the prototype only in offering an enclosed cabin and, later, the 60 kW (80 hp) Rotax 912 flat-four engine.