Arguably the most exciting sector within Light-Sport Aircraft are the LSA seaplanes. One company, Icon Aircraft and its handsome A5, has attracted enormous attention. Nothing wrong with that, in fact, the company’s superb marketing has been helpful to the entire LSA industry.
However, despite all the media coverage, this California producer is one of the later entrants to the LSA seaplane party. A few came before and one of them is back in action.
The SeaMax LSA seaplane designed and previously manufactured in Brazil has been somewhat absent in recent years. We’ll skip the details, but the company, AirMax, used a lot of energy to repel an undesired takeover. In recent months that was resolved and AirMax is now ready to move forward.
SeaMax was an early LSA to meet the consensus standards as required by FAA before sales to the public can begin. The first was the Mermaid in February 2006. Next came the Colyaer Freedom on January 2007. On Christmas Day 2007, SeaMax became the third.
However, of those three only SeaMax has remained in regular production for the last 10 years.
More recently, SeaMax was followed by SeaRey, Super Petrel, and A5 as ASTM-compliant LSA seaplanes.
At SUN ‘n FUN 2017, I had a discussion and conducted a video interview with SeaMax designer Miguel Rosario about his 22nd design project.
Because I have enjoyed flying the SeaMax, let me provide some flight experiences with this Brazilian LSA seaplane.
Bigger Than It Looks
Though the aircraft looks rather small as you approach it, SeaMax’s interior is surprisingly roomy and its interior has a handsome speedboat-like finish with a generous 46-inch width, close to the broadest LSA and half a foot wider than a Cessna 172.
Entering is simple with its canopy that tilts well forward out of your way. You step on the solid floor and sit. Simple. SeaMax’s canopy optics were superb and you have 270° visibility thanks to rear quarter windows.
Because you’ll want the canopy closed in the water — the airplane sits low — air vents are positioned in the canopy with a second set near your head, tucked away in the wing root area. These keep air flowing inside.
When taxiing on land you can leave the canopy open. The hinges are robust so that even on a bumpy turf runway, the canopy moves very little.
After rolling off the ramp or beach, you retract the gear in preparation for launch. SeaMax’s electromechanical landing gear takes nine seconds to fully retract.
To help you fully prepare, SeaMax offers a digital flap position indicator and digital trim position indicator. You also flip on an electrical fuel boost pump and a relatively uncommon bilge pump prior to moving the throttle forward. Both can be switched off once you are safely airborne.
A 100-horsepower Rotax 912 moves SeaMax enthusiastically on land or water.My preparatory experience on the water at 45 mph showed SeaMax to be a great little speedboat. Turning in this configuration employs the water rudder, which extends from inside the air rudder. You cannot see it when retracted. You use opposite aileron to keep from sticking a sponson too deeply in the water.
After a few minutes of proving the boat capabilities of SeaMax, I was anxious to go aloft.
On full application of power, some water spray may contact the prop, so SeaMax uses a metal reinforced prop leading edge.
As mentioned earlier, the cockpit side rails in SeaMax are only inches above the water line. The bottom of the occupant seats are below the water line. Until your technique is experienced, I consider this a lake airplane, although I heard reports of operations in one-foot waves. I recommend caution regarding ocean operations. Such restrictions are common on smaller amphibians.
My checkout pilot, Carlos Bessa, who was instrumental in SeaMax winning FAA acceptance as a Special LSA, suggested I apply full power with the stick held full aft until breaking water or ground.
As the nosewheel lifts, you relax the back pressure and let the plane fly itself off the surface. Rotation occurred at about 45 mph indicated on the Dynon instrumentation.
SeaMax’s hull gets on the step in about 100 feet, according to company officials. With continued acceleration, takeoff follows in about 300 feet total when flying solo or about 500 feet when flying dual.
Climbout at 70 mph produced about 1,000 fpm initially. SeaMax sustained climb at about 700 fpm with 10° of flaps.
During landings with full flaps, the aircraft approaches at 50 mph. A safe downwind speed is 75-80 mph; this produces about 500 fpm of sink with the throttle at idle thrust.
Water touchdowns proved very straightforward. SeaMax responds very well as a boat. Touchdown was at about 60 mph and it immediately started tracking true.
My check pilot said it is essential to keep the stick full aft to prevent porpoising and possible upset. This is another common seaplane technique.
Boating Around In The Air
Airborne, the SeaMax joystick has a light touch, although I recommend a few hours to optimize. My initial efforts at mild dutch rolls were sloppy, suggesting handling that takes a bit of acclimatization. Rudder control took the most finesse, perhaps due to close coupling behind a wide cabin combined with a pusher engine. You need to use the rudder but bumps of it, rather than steady pressure, worked best for me.
Light and responsive SeaMax controls will delight pilots who take the time to get used to them. Roll rate was medium to somewhat fast. You rarely have to land crosswind on the water in a seaplane but on land, SeaMax has all the control authority it needs.
To smooth airflow around the large cabin, designer Rosario put in a long investigation into the vortex generator tabs seen in various locations.
Bessa recommended I use 4,800 rpm on the 100-horsepower Rotax 912 for normal cruise. That produced about 100 mph (87 knots). At 4,600 rpm we showed slightly less than 100 mph, but these are low, fuel-conserving power settings.
Push the Rotax a bit harder and SeaMax reached 115 mph (100 knots), putting it in the speedier range compared to other LSA seaplanes.
To be certain you have the latest available information, I suggest you get the official specifications from the factory.
Stalls were mild in my trials. From most entries, stalls appeared to break benignly in the low 40 mph range, though the factory says 36 mph with optimal flaps. Longitudinal stability checks and power changes showed SeaMax to be a generally stable aircraft. It recovered from mild disturbances of the stick on its own and with only a few oscillations.
With 26 gallons of fuel on board and the fuel-miserly Rotax 912, you can stay aloft for more than five hours, which translates to around 500 statute miles plus some reserve. Seating is comfortable enough for that duration, but I think you’ll be hard pressed to pass up all those tens of thousands of lakes scattered around the United States.
With 600 pounds of useful load, and even with full fuel on board, you can put more than 440 pounds inside SeaMax. Luggage area is limited, but it will easily get you to that $100 hamburger at either a marina or airfield.
In summary, I’d call SeaMax a “performance LSA seaplane,” peppy and demanding a bit more pilot attention, but it gets up and goes. When stopped at an airport or marina, pilots or boaters will be checking out SeaMax and most will be impressed.
Enjoyment awaits in SeaMax. The rest is up to you.