Abstract <p>The air-cushion craft that had appear in the thirties of the last century have been thus far among the best two-medium vehicles. However, the caterpillar tracked surface craft developed in recent years (snow mobiles) are in certain cases not inferior to them as concerns their running and operation performance. They are capable to roll over the water surface at a large velocity, their advantages being obvious in the case of motion over dry and shallow water. We note also that that the caterpillar tracks play the role of loth load-bearing surfaces and propulsors, which offers also certain advantages. In this paper, we discuss the hydrodynamic forces acting on caterpillar tracks in the case of the rolling over a free water surface and present certain experimental data.</p>