Hydroplanes may push some air under their hulls due to their high speed forward motion. I don't know if this really helps all that much, but I suppose it might. This doesn't use a compressor however.

If you used a compressor to force air under a slower moving boat, it might actually slow the boat down. The air would form bubbles, which have a lower density that water. This lower density material under the boat will not support the weight of the boat as effectively as the denser water does. As a result, the boat will float deeper in the water. This will force the boat to have to push more water out of its way to move forward. I don't know if this effect would be all that serious though. It might not sink enough to matter. The air might reduce surface friction enough to improve overall performance, but probably not much. And the compressor will consume at least some power, which would reduce efficiency gain. It would also add weight.

first off, dwayne, i usually like your comments, but you are wrong this time, it would not lower the floating level of the boat, it would minutely raise it, because the boat has constant weight, regardless of the air, so it displaces the same amount of water either way, and the air basically acts as a layer of the hull, making it wider, so it displaces that water with less depth. anyway, back to the idea, it would probably work, but so much air would be needed to maintain the bubble, that it would probably take less energy to just add the engine power for the same speed.

Drewnahant, thanks for keeping me honest. My suggestion that the boat would float lower was based on a well known principle as discussed here. However, that probably doesn't apply if the bubbles are all in close contact with the hull.

In answer to the original question, yes, this has been studied. In fact it has been researched for over a century. An article about it here says that it shows great promise.

Providing enough bubbles to make a difference is probably the biggest difficulty. The Russian Shkval torpedo uses a rocket motor as the gas generator to do just this and it is able to travel 200knots+ underwater. But a rocket motor is very short-lived--it would be hard to duplicate this much gas output for an extended time period.

http://en.wikipedia.org/wiki/VA-111_Shkval_torpedo

thanks for the input. The idea was not to increase speed, but to increase efficiency, since sea-state determines speed. It seems if there is less wetted area, less power would be needed for the same speed. The size of the bubbles could be small, and they can only travel in a rearward direction plus they would expand due to the release of pressure after exiting the discharge holes. It may only require a single full width strip, lets say 1/4 inch, and be fed by a automobile air conditioner compressor (which already can be mounted to most engines) from above the water line for testing. Wish I had a boat to try it on.