DESIGN OF ICE BOOMS
nent above-water anchors, such as rock islands, sheet-pile cells,
and timber and rock cribs can be used. These above-water anchors
provide the added benefit of increasing the overall stability of a
sheet ice cover.
Anchor lines are generally made of wire rope. However, if the
boom is being used in a large water body with commercial navi-
gation, anchor lines of high strength anchor chain may be prefer-
able, because a chain being more flexible will lie on the bottom
without coiling. Furthermore, a chain is more resistant to abrasion
if the bottom is rocky.
If the boom has midstream anchors, a junction plate must be
used to connect the two boom cables to the single anchor cable.
Because these junction plates must be designed for high loads,
they usually require additional flotation to support their weight
and prevent the boom from submerging near the anchor attach-
ment points. This additional flotation is also needed to support
parts of the submerged weight of the anchor cable and the adja-
cent boom cables. Figures 8 shows a typical junction plate design,
and Figure 9 shows a typical junction plate and float arrange-
8. Example of junction
plate design. Note the
reinforcing steel plates
welded to each side of
the three holes.