On August 18, 1994, about 1802 Atlantic standard time, a Piper PA-23, N556PR, registered to Francisco Soto, ditched in San Juan Harbor, San Juan, Puerto Rico, following loss of engine power during takeoff from Fernando Dominicci Airport, while on a 14 CFR Part 91 pleasure flight. Visual meteorological conditions prevailed at the time and no flight plan was filed. The aircraft received substantial damage and the private-rated pilot and one passenger were not injured. The flight was originating at the time of the accident. The pilot stated that during takeoff the left engine lost power. The aircraft drifted to the left and did not climb high enough to clear a construction crane located to the left of the runway. The left wing of the aircraft struck the crane and the aircraft descended and crashed upright in the water. The left engine separated from the aircraft on impact and was not recovered. The pilot stated on his aircraft accident report to NTSB that he did not have any mechanical failures and that loss of power in the left engine was attributed to his failure to properly drain water from the fuel tanks. Federal Aviation Administration records indicate the pilot holds a private pilot certificate with a airplane single engine land rating. The pilot does not hold a airplane multi-engine land rating. The pilot reported he has 6 hours of pilot-in-command time and no dual instruction time in multi-engine aircraft.