[Sidenote: III 63]
The “Gierpont” (flying bridge) allows a stream to be crossed as follows:
The operating cable is attached at one end to an anchor put down
upstream near the middle of the river and at the other end to the
middle of the upstream side of the boat. The two ends of the pontoon
are then fastened by special lines to the swinging cable. The pontoon
can, in this way, be made to lie at an angle to the current. The
component of the current normal to the side of the boat causes it to
cross in describing an arc of a circle around the anchor as a centre
and with the length of the cable as a radius. The speed is regulated
by changing the angle which the axis of the pontoon makes with the
direction of the current.
In order to assist the action of the current on the pontoon, two or
four lee-boards are fastened to the upstream side, that is: the side
next to the cable, one or two of them serving to cross the stream to
the right bank, the other one or two, to the left bank.
In order to diminish the resistance of the cable in the water, it is
supported by a few small boats called “onderlegaakjes”.
A “Gierpont” of this kind works, among others on the Meuse, at the
Gravenbicht-Rothem (Limbourg) and Grave crossings.