TM 5-1940-321-13&P
(b) Another indicator is the location of spray coming from under the craft. When
planning, a properly trimmed craft will have the spray visible about half way
between the bow and the stern. The outboard engine trim angle may require
adjustment if the loading of the craft is changed. When the outboard engine
trim angle adjustment is not correct, the thrust line is not parallel with the
surface of the water. Some of the engine thrust is then wasted in driving the
stern of the craft up or down instead of straight ahead.
(c) The lower end of the outboard engine is shaped for low drag when the
engine thrust line is parallel to the surface of the water. Drag is increased
when the outboard engine trim angle adjustment is incorrect. This reduces
speed, increases fuel consumption, makes steering difficult, and shortens
engine life. Additional outboard engine installation data is contained in the
following paragraph.
c. Outboard Engine Adjustment. The outboard motor must be mounted in the center of the
transom. Refer to the engine manufactures operation manual for proper installation and operation
instructions.
CAUTION
Do not operate the F530 IAB until the engine has been installed in
accordance with the engine manufactures operation manual.
d. Sea Conditions and Weather. Sea conditions and weather affect performance of the F530 IAB.
The best performance is achieved in calm sea conditions. Experience and coxswain training will help leaders
plan for the impact of weather on F530 IAB performance.
e. Flooring System. The F530 IAB is delivered with a Rigid Flooring System. A Roll-Up Flooring
System is available. The rigid flooring system is described in chapter 2, paragraph 2-8b. The performance of
the F530 IAB will vary depending on the type of flooring system. The improved performance of the rigid flooring
system is more noticeable when the craft is operated with high payloads over rough water and at higher
speeds and greater distances.
f. Inflation Pressure. A craft with low are pressure in the buoyancy tubes or inflatable keel will have
lower speeds, increased fuel consumption, and degraded handling. Operating the F530 IAB with low air
pressure will reduce service life. Air pressure must be checked and adjusted daily as described in chapter 5,
4-3
