TYPE: Two-seat amphibian kitbuilt; four-seat amphibian kitbuilt.

PROGRAMME: Derived from earlier ultralight version, with 59.7 kW (80 hp) engine and metal strut-braced wings, of which some 20 flying in Italy by 2002. First all-composites Sea Storm under construction in 2000/01 by SG's North American agent, Eric Dixon and first flew (N221ST) October 2001. Ultralight Sea Storm with carbon wing and bracing struts under construction in 2003.

CURRENT VERIONS: Z2: Two-seat; baseline version.
Z4: Four-seat; increased wing span and power.

CUSTOMERS: Three sold in USA by April 2002; one Z2 to Australia in 2003. 26 sold (including earlier ultralight) by 2003.

COSTS: Z2 €73,130 (kit), €113,259 (complete). Z4 €82,478 (kit), €125,189 (complete) (2003).

DESIGN FEATURES: High, constant-chord wing, moderately sweptback tailplane and highly sweptback fin; pusher propeller immediately aft of wing trailing-edge; mid-positioned stub-wing with stabilising floats. Quoted kit build time 700 hours.

FLYING CONTROLS: Conventional and manual. Plain flaps.

LANDING GEAR: Optional retractable wheel landing gear attached immediately outboard of wingroots.

POWER PLANT: One pusher piston/rotary engine.
Z2: Option of 73.5 kW (98.6 hp) Rotax 912 ULS or 84.6 kW (113.4 hp) Rotax 914 flat-four or 70.8 kW (95 hp) Mid-West AE 100 rotary driving an adjustable-pitch propeller. Textron Lycoming engines in the 82.0 to 119 kW (110 to 160 hp) range are also suggested. Standard fuel capacity 140 litres (37.0 US gallons; 30.8 Imp gallons), with optional extra 79 litre (20.9 OS gallon; 17.4 Imp gallon) tanks available.
Z4: One 157 kW (210 hp) Textron Lycoming O-360; engines recommended in the range 149 to 224 kW (200 to 300 hp). Fuel capacity 200 litres (52.8 US gallons; 44.0 Imp gallons) as standard; optional 61 litre (16.1 US gallon; 13.4 Imp gallon) tanks available.
Idrovario hydraulic, flight-adjustable pitch, two- or three-blade propeller.

ACCOMMODATION: Two (side by side) or four persons in enclosed cabin with centreline-hinged door each side.