From an engraving of an icebreaker made in the 1730s it becomes clear how such a vessel was built and how it operated on the canals removing the ice. Such a boat is operated by a dozen men of which six work on the vessel, while the others are on the ice or the levee of the canal. The boat has a broad and flat prow with several rods bending down. Between the rods iron plates have been installed. Because the boat needs to split the ice in front of it there is an extra weight of 18,000 pound at the foredeck pushing the prow downwards causing the thick ice to break. The ice blocks move underneath the boat and re-emerge at the stern. There the blocks are measured and handled to be sold to private persons in their ice-cellars. On the icebreaker there is a very strong mast to which two thick and long ropes are fastened. Around the mast there are many hooks, axes and saws. The saws were used by men checking the ice in front of the boat and trying to saw some parts into pieces, which is depicted on another engraving of an ice breaker at work. Finally the two ropes go towards two packs of horses, both packs consisting of twenty horses, totaling 40 horses pulling one big ice breaker through the ice. Because the distance between the ice breaker and horses is quite large and the noise of breaking ice and working horses is loud, the commander on the ice boat uses a primitive loudspeaker to command the horse drivers.