Narrative:

We were flying the willamette river just south of downtown portland; or; in preparation for his sel and ses check ride. We had just departed the sea plane base and back 'water' taxied approximately 500-600 yards down river towards downtown in order to have plenty of room to execute a normal water takeoff up river and into the wind. It was a beautiful day and there was moderate boat traffic on the river. We cleared the area around and behind us; completed our takeoff checklist; and executed a turn into the wind and up river. It seemed that as we maneuvered into position and after we turned all of our lights on; that all the boats in the general area pretty much motored towards the sides of the river. We began our takeoff run and for a split second our nose was high as we were coming onto our 'step.' once the nose of the aircraft leveled out; we accelerated relatively quickly. As we were nearing flying speed a cigarette boat; traveling at very high rate of speed; came around the corner under the bridge and was upon us. I believe the boat operator noticed us just in time but because of the speed he was carrying he could only alter his course slightly. However; in doing so he cut right in front of us. We were traveling too fast to chop the throttle and maneuver as not to create a hazard to the other boat operators or ourselves; yet too slow to fly. When we hit his wake we became airborne. We grabbed a hand full of flaps so not to slam back into the water. Once in ground effect we accelerated to a speed too fast to avoid any obstacles which may have come across our path and yet too slow to climb above the bridge beginning to fill our windscreen. We were left with only one safe option...fly under the ross island bridge. We were approximately 5-10 ft above the water 40-50 ft under the bridge. When we cleared the bridge it was vx then vy to an uneventful climb to 1500 ft heading south up river. That was without a doubt too close for comfort. As the PIC; the ultimate responsibility for the safety of flight lies in my hands and I believe we made the safest decision for the situation which dictated split second thinking.

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Original NASA ASRS Text

Title: UNEXPECTED HIGH SPEED BOAT TRAFFIC CAUSES INSTRUCTOR PLT AND STUDENT ABOARD FLOAT EQUIPPED PA18 TO BECOME AIRBORNE PREMATURELY. UNABLE TO CLIMB OR MANEUVER DUE TO INSUFFICIENT AIRSPEED; THE ONLY SAFE PATH WAS TO FLY UNDERNEATH THE BRIDGE DIRECTLY AHEAD OF THEM.

Narrative: WE WERE FLYING THE WILLAMETTE RIVER JUST S OF DOWNTOWN PORTLAND; OR; IN PREPARATION FOR HIS SEL AND SES CHK RIDE. WE HAD JUST DEPARTED THE SEA PLANE BASE AND BACK 'WATER' TAXIED APPROX 500-600 YARDS DOWN RIVER TOWARDS DOWNTOWN IN ORDER TO HAVE PLENTY OF ROOM TO EXECUTE A NORMAL WATER TKOF UP RIVER AND INTO THE WIND. IT WAS A BEAUTIFUL DAY AND THERE WAS MODERATE BOAT TFC ON THE RIVER. WE CLRED THE AREA AROUND AND BEHIND US; COMPLETED OUR TKOF CHKLIST; AND EXECUTED A TURN INTO THE WIND AND UP RIVER. IT SEEMED THAT AS WE MANEUVERED INTO POS AND AFTER WE TURNED ALL OF OUR LIGHTS ON; THAT ALL THE BOATS IN THE GENERAL AREA PRETTY MUCH MOTORED TOWARDS THE SIDES OF THE RIVER. WE BEGAN OUR TKOF RUN AND FOR A SPLIT SECOND OUR NOSE WAS HIGH AS WE WERE COMING ONTO OUR 'STEP.' ONCE THE NOSE OF THE ACFT LEVELED OUT; WE ACCELERATED RELATIVELY QUICKLY. AS WE WERE NEARING FLYING SPD A CIGARETTE BOAT; TRAVELING AT VERY HIGH RATE OF SPD; CAME AROUND THE CORNER UNDER THE BRIDGE AND WAS UPON US. I BELIEVE THE BOAT OPERATOR NOTICED US JUST IN TIME BUT BECAUSE OF THE SPD HE WAS CARRYING HE COULD ONLY ALTER HIS COURSE SLIGHTLY. HOWEVER; IN DOING SO HE CUT RIGHT IN FRONT OF US. WE WERE TRAVELING TOO FAST TO CHOP THE THROTTLE AND MANEUVER AS NOT TO CREATE A HAZARD TO THE OTHER BOAT OPERATORS OR OURSELVES; YET TOO SLOW TO FLY. WHEN WE HIT HIS WAKE WE BECAME AIRBORNE. WE GRABBED A HAND FULL OF FLAPS SO NOT TO SLAM BACK INTO THE WATER. ONCE IN GND EFFECT WE ACCELERATED TO A SPD TOO FAST TO AVOID ANY OBSTACLES WHICH MAY HAVE COME ACROSS OUR PATH AND YET TOO SLOW TO CLB ABOVE THE BRIDGE BEGINNING TO FILL OUR WINDSCREEN. WE WERE LEFT WITH ONLY ONE SAFE OPTION...FLY UNDER THE ROSS ISLAND BRIDGE. WE WERE APPROX 5-10 FT ABOVE THE WATER 40-50 FT UNDER THE BRIDGE. WHEN WE CLRED THE BRIDGE IT WAS VX THEN VY TO AN UNEVENTFUL CLB TO 1500 FT HEADING S UP RIVER. THAT WAS WITHOUT A DOUBT TOO CLOSE FOR COMFORT. AS THE PIC; THE ULTIMATE RESPONSIBILITY FOR THE SAFETY OF FLT LIES IN MY HANDS AND I BELIEVE WE MADE THE SAFEST DECISION FOR THE SITUATION WHICH DICTATED SPLIT SECOND THINKING.

Data retrieved from NASA's ASRS site as of January 2009 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.