Oak was a test of prototype devuce for TX-46 system designed in Los Alamos. The device was similar to those used in Butternut and Yellowwood, which was a failure. Because of the Yellowwood device failure changes were made to Oak test device, basically secondary stage was bumped up. The result ws remarkable, especially compared to previous failure. Predicted yield of 7.5 Mgt was exceeded by over one megaton, resulting in yield of 8.9 Mgt detonation. By the way, mainly it was the fusion yield that was increased, not the fussion. Instead of 4 mgt fission accounted for 5 mgt yield. Thus, Oak became 6th largest nuclear detonation even conducted by US.
The etst wa sconducted in the lagoon, although the water was very shallow, only 12ft deep. Oak test device itself was on the small barge. Explosion produced a crater that was 204ft deep and had 5740ft diameter.
The Oak test device was 100.5 inches long cylindrical shaped object, with 37 inches in diameter and weighed 6113 lb. This design eventually became 9 Mt W/Mk-53 warhead used on the Titan II missile and in the Mk-53 strategic bomb. Actually it became one of the longest lastign designs in US nuclear armament, being in service till 1997.