RECOVERY PROCEDURES (CONT.)
STEP 4. OBTAIN RESISTANCE
Compute the tackle resistance and total resistance.
Determine the resistance of the tackle. The percent of
the load resistance, as determined in STEP 2, is multi-
plied by the number of sheaves in the rigging. The
determined resistance of the tackle added to the load
resistance equals the total resistance.
Total effort available is winch capacity multiplied by the
mechanical advantage, as computed in STEP 3. If effort
available is more than total resistance, proceed to STEP
If it is less, go to STEP 3 and add mechanical
STEP 5. VERIFY SOLUTION
Compute line forces to compare with the winch and dead
line capacities. Divide the total resistance (STEP 4) by
the mechanical advantage (STEP 3). The result is the
force of the fall line. The fall line force must be less than
the capacity of effort. Therefore, this step of the recovery
procedure is the key step to solving the problem.
When verifying the solution, if the computed fall line
force is greater than the effort, the mechanical advan-
tage must be increased. Note that no physical work has
occurred up to this point. As a result,
no time is lost moving equipment or
having to re-erect rigging equip-
ment. Compute the dead line
force, determine the required
strength of equipment capacity
and choose the correct equip-
ment to use as dead lines.