ACCORDING TO THE PILOT, THE RIGHT ENGINE LOST POWER AT OR SHORTLY AFTER ROTATION FOR TAKEOFF. REPORTEDLY, THERE WAS INSUFFICIENT ROOM TO STOP ON THE RUNWAY WITH A HOUSE NEAR THE END. HE OPTED TO CONTINUE THE TAKEOFF AND FLY TO A SAFE LANDING AREA. HE STATED THAT HE FEATHERED THE RIGHT PROPELLER AND STARTED THE GEAR UP, BUT WAS UNABLE TO EITHER CLIMB OR MAINTAIN HIS AIRSPEED. THE SPEED DETERIORATED TO VMC OR BELOW AND REQUIRED A DESCENT TO JUST ABOVE THE WATER LEVEL OF A LAKE. DURING THIS TIME THE LEFT ENGINE POWER WAS REDUCED TO PREVENT A ROLL TO THE RIGHT. THE PLANE CONTINUED ACROSS THE LAKE FOR ABOUT 1 MILE. WITH THE FAR SHORE AND HIGHER TERRAIN APPROACHING, THE PILOT DITCHED THE PLANE, AND ABOUT 5 MINUTES LATER, IT SANK IN ABOUT 85 FT OF WATER. THE PLANE WAS RECOVER AND THE RIGHT ENGINE WAS STARTED AND AFTER IT WAS CLEANED AND A NEW STARTER VIBRATOR WAS INSTALLED. THE ENGINE WAS OPERATED TO THE RATED RPM.NO PREIMPACT MALFUNCTION WAS VERIFIED DURING THE INVESTIGATION.