Ventilation And Drainage Systems; Engine Compartment Ventilation; Natural Ventilation System; Forced Air Ventilation - Scarab jet boat Owenrs Manual

B - 7 VENTILATION & DRAINAGE
SYSTEMS
A. Engine Compartment Ventilation
All Scarab jet boat models are equipped with engine
compartment ventilation. This system is designed to
meet or exceed the requirements (in effect at the time
of manufacture) of the U.S. Coast Guard, the National
Marine Manufacturers Association, and the Ameri can
Boat and Yacht Coun cil.

1. Natural Ventilation System

This system includes air intake and exhaust com-
ponents. The air and exhaust ducts reach to the lower
bilge area. This provides adequate air movement
while underway and during bilge blower operation.

2. Forced Air Ventilation

All Scarab models are equipped with an electric bilge
blower. The bilge blower provides the venti lation
required prior to starting the en gines and while at idle.
See Sec tion B-5C - 12 Volt Electrical Equipment for
blower operation instructions.
Gasoline vapors can explode resulting in injury
engine com part ment bilge for gasoline or
vapors, and operate blower for four (4) minutes,
and verify blower operation. Run blower when
vessel is operating below cruising speed.
AL WAYS oper ate the bilge blow er while the
engines are at idle.
3. Engine Ventilation System Mainte nance
Periodic inspection and cleaning of the ventilation
ducts is necessary to ensure adequate air circula tion.
A buildup of leaves, twigs, or other debris can severe-
ly reduce ventilation. Be sure bilge water does not
accumulate to a level that would obstruct the ventila-
tion ducts.
Blower operation can be tested by placing a hand
over the vents. DO NOT rely on the sound of the
blower. Be sure a substantial amount of air is being
exhausted by the bilge blower. Check the bilge blower
system often, preferably before each cruise.
Boat Systems - Section B
Should blower noise and vibration be excessive,
loosening the bilge blower mounting screws and then
tightening evenly usually reduces noise considerably.
B. Hull Drainage Systems
1. Transom Drains
Transom drains with plugs are provided in the engine
compartment to allow water drainage. When the boat
is out of the water, the boat and trailer should be
positioned so any bilge water accu mula tion during dry
Be sure the drain plugs are securely in place
prior to launching the boat. Upon ship ment of
the boat, the drain plugs are usually taped to
the steering wheel.

2. Bilge Pump

A bilge pump is provided in the bottom of the hull to
remove miscellaneous water accumulations that might
occur during normal boating or weather conditions.
The bilge pump is controlled by the bilge pump switch
on the dash panel. See Sec tion B-5C - 12-Volt
Electrical Equipment for a detailed descrip tion of the
bilge pump switch .
The bilge pump is typically equipped with an automatic
will activate the pump. When leaving the boat unat-
tended for long periods of time or during excessive rain
storms, it is a good idea to check on the boat for exces-
sive water accumulation. Be sure both the bilge pump
operating time of the bilge pump will be limited to the
battery capacity.
NOTICE
While at rest, any bilge water accumula tion may
shortly after getting under way and while the
boat is at a sub stantial running angle. DO NOT
allow bilge water to accumulate. Damage to the
engine or other compo nents may result.
Periodically, clean the bilge pump strainers. DO NOT
allow dirt and debris to clog the bilge pump intakes.
ensure movement of the switch is not restricted by
debris, portions of the hull, etc. Wipe up any oil
The
Owner's Manual Page 63