Patent ID: 7971385

Claim:
An under ice crawler lowerable through a hole in a layer of ice into a body of water therebeneath and operable to extend a flexible line within the body of water between two points spaced apart along the layer of ice, the crawler comprising: a floating body having sliding surfaces defined at an upper limit thereof to allow sliding of the floating body along the layer of ice against an undersurface thereof; an electrical power supply carried on the floating body; a motor carried on the floating body to selectively drive a propeller when powered by the electrical power supply via a control circuit between the motor and the electrical power supply, selective operation of the motor driving the floating body in a forward direction within the body of water below and along the layer of ice; a connector carried on the floating body to facilitate the connection of the line thereto, the connector comprising an eyebolt supported for axial sliding movement relative to the floating body in a passage that is defined thereon and extends along the forward direction; a termination device carried on the floating body and operably linked with the motor to terminate operation thereof upon actuation of the termination device; and a starting device operatively linked with the motor and comprising: a starting-signal receiver carried on the floating body and actuable to effect starting of the motor thereof upon detection of a starting-signal; and a starting-signal generator separate from the floating body and configured to be manually operable from above the layer of ice to deliver the starting-signal to the starting-signal receiver without physical contact with the floating body, or any component carried thereon, below the layer of ice; wherein the termination device comprises: a terminating magnetic switch fixed to the floating body; a terminating magnetic source mounted on the eyebolt, the eyebolt and the terminating magnetic source mounted thereon being slidable out of a position proximate the terminating magnetic switch by application of a pulling force to the eyebolt in a rearward direction opposite the forward direction; and a spring fitted about the eyebolt between a collar fixed thereon and a stop defined at a fixed position along the passage to bias the eyebolt and the terminating magnetic source mounted thereon into the position proximate the terminating magnetic switch, in which position the terminating magnetic source exerts a magnetic field on the terminating magnetic switch to close a portion of the control circuit between the motor and the electrical power supply, whereby the termination device is actuable to terminate operation of the motor by pulling of the eyebolt out of the position proximate the terminating magnetic switch to open the portion of the control circuit between the motor and the electrical power supply.