Icebreakers tend to be pretty large vessels.
Today’s invention would allow smaller ships to pass through icier waters than at present.
Imagine a large, slow-revving marine engine which can adjust its crankshaft so that all of its cylinders fire at the same time and with the crank in the same rotational position.
The effect of this mode of operation is to cause the ship to oscillate vertically in the water as it powers forwards.
In so doing, a set of large teeth on the bow saws into the surrounding ice, causing it to crack and allow the ship to move ahead.