Water Based Ufo Sightings

I am captain of foreign going vessels since 1970. In 1968 I was second officer on Panamax bulk carrier Swiss flag named GRICHUNA. We departed full loaded with coal from Norfolk or Charleston bound for Japan through Panama channel.

I was on the night watch from 0000 -0400 and we were sailing south off coast of Florida.The sea was calm and our speed was 15-16 knots. The weather was fine and the visibility very good.

I was on the command bridge outside on the port side and looking to the lights of Palm Beach in distance just abeam and then I saw the lights under the surface some 30-40 meters away just abeam in the depth of some 10-15 meters. It looked like a big airplane without wings, tail with all the windows lit on it. There were some 10-15 windows, but I did not count them.

The object was moving with us but some 30 degrees. crossing our course. The speed was about double of ours and it went under the bow of our ship and I could see just a gloom when it came on the other side in front of port bow. Our ship was 250 meters long and her draft was some 9 meters.

There was AB seaman with me on the bridge but standing by on the wheel even if we were on automatic and I did not call him outside earlier but ask him later if he could see something in the sea left of the port bow. He confirmed he see a gloom under water. Now what was it?

I excluded a submarine as they have no windows-they would not risk to pass so close under our ship and finally some 30 knots was too great of speed for a submarine in 1968.

A sight seeing submarine has windows, but what would she be doing in plain night on open seas (10 NM off coast) and again risking collision and too big speed and even the size (about 40 meters) for her.