Mechanical Propulsion Components - Hunter H31 Operator's Manual

Underwater Gear
Your underwater Gear consists of the following:
• Propulsion components (sail drive)
• Steering components
• Seawater Intake, and discharge skin fittings
• Monitoring Equipment
• Keel

6.1 Mechanical Propulsion Components

Keep clear of moving parts at all times. Protect
moving parts from access during normal use.
Propulsion components are any component that would
be involved in the movement of your boat. This section
will detail the components that are submerged or under-
water most of the time. Fig 6.1 will detail most of the
components.
6.1.1 Propellers
The propeller supplied with your boat has been select-
ed as the best propeller for average use. Propellers
use "pitch" or the angle of the blades to determine
the amount of power exerted from your engines. Do
not change the pitch of your propellers without get-
ting your dealers recommendations first. If you change
to a different propeller pitch, under no circumstances
use a propeller which allows the engine to operate
Hunter 31 • Underwater Gear
at a higher than recommended RPM. Your engine
manual will specify the maximum recommended RPM.
To maintain rated power, propellers should be free of
nicks, excessive pitting and any distortions that alter them
from their original design. Badly damaged propellers
should be replaced, but those that are chipped, bent or
merely out of shape can be reconditioned by your marine
dealer.
Consider keeping an extra propeller on your boat. If the
propeller becomes damaged, you can replace it with the
spare and continue your outing. Check with your dealer
if you want to purchase one.
6.1.2 Propeller Shaft
The propeller shaft is made of Aquamet 19 or equivalent
stainless steel which has excellent corrosion resistance
and very high strength. The coupling at one end of the shaft
is bolted to the transmission. The other end of the shaft is
tapered, threaded, and keyed for installation of the propel-
ler. The propeller shaft passes through the hull encased
in the shaft log. Then, on the underside of the hull, is
attached a strut, which holds the propeller shaft in position.
6.1.3 Alignment
Aligning the engine with the propeller shaft is critical for
smooth operation of your boat. Shaft alignment may
change slightly after your boat is in use. Your dealer
should check alignment as part of commissioning, par-
ticularly if there is vibration, a drumming sound, or loss
of RPM's.
Below is an illustration showing the steps for alignment,
however we recommend this practice be performed by
competent professionals.
6.3