Page 177 - NAVAL SCIENCE 3 TEXTBOOK

BASIC SEA;\IANSHIP 183

Propulsion and the Rudder
The propulsion machinery all n powerboat is called thc el1gitIC. and
on a sailboat, the nllxilimy. Boat engines may be either gasolinc- or
diesel-fueled. The}' tr,\Ilsmit their power to the propeller or screw
under the stern via the propel/er shajt, which corresponds to a drivc
shaft on a car. 1\·105t powcrboat propellers are three-bladed; some
sailboats hnve a two-bladed propeller that can be aligned with the
back of the keel to reduce dr<lg through the Wi.lter while operating
all sail 'llone. Powerboats may hiwe one or more engines; they may
be perlllilllently instnlled inside the hllll, in " ,hleh casc they are called
il/bo(/rd, or they may be semiportable and on the stern, in which cnse
they are called olltbonrd. I\·fost Nnvy small boats have engines of the
Sailboats, like the two-masted one shown here, have a low upper- inboard type. Nei.lr the propeller is the maaer, or in some cases two
works to allow for free movement of the sails. All except the very rudders, that control the direction of travel of the bont.
smallest usually have some sort of auxiliary engine for propulsion
when the sails are daVin.
Types of Boats
The position of the steering gear for the boat, which may
There are hundreds of difterent types of s,lilboats and powerboats,
be inside or outside the cabin, or in some cases both, is called
collectively called pleasllre boats if the}' ,lre operated mainly by
the hellll. In many sailboats, the helm is located ill the cockpit,
civili<lI1s as leisure-time activities. In the NilYY, most powerboats.
a depressed area aft of the cabin, or, in some cases, amidships
c<tUed SI1I(1l/ emfr, with which NJROTC cadets will come into con-
between two cabins. The edge of the deck, called the mil, usually
tact fall into one of oilly a few cntegories: amphibious natt. utilit)'
has vertical metal stanchions that support one or more rows of
bonts, officers' boats, and inllatables.
lifelillcs. In the front of the bow on most sailboats and many pow-
erboats is the pulpit, a wooden platform that overhangs the bow
and provides room to handle the forward sail and anchor. It may
be supported underneath by the bOll'sprit, a beam that extends
from the bow beneath the platform. Some powerboats have an
auxiliary helm i.1I1d engine controls on a platform elevated for bet-
ter visibility called aj1yillg bridge.
Sailboats have one or more vertical poles called mnsts llsed
to support one or more sails, collectively called the rig of the sail-
boat. A powerboat may have a short stubby mast for the radar and
radio antennas, and on some types called trall'lers these may even
be high enollgh to cany a steadying sail. If i1 sailboat has two or
more masts, one is the /linin, and the other the mizzell (if <ltt of the
mainmast) or forell/ast (if forwnrd of the mninll1ast). The position
of the mainmast l11a), Vaf}' according to the type of rig the bOilt
has .. Metal wires. rods, or lines used to sllpport the masts are the
stmldillg riggillg. and the various lines used to support and control
A landing craft utility (LeU) makes ready to offload a group of
the sails arc the flllIllil/g riggillg. Horizontal supports near the top
Marines. (Geronimo Aquino)
of the masts that support the standing rigging are the sprcnaers.,
and horizont<tl poles near the b<tse of the masts used to support the
Amphibiolls cn~ft include sllch boats as landing craft of severnl
bottom of the sails arc booll/s.
sizes and types, some of which are equipped with bow ri.ll11pS that
There is a great deal of other nomenclature peculiar to sail-
can be lowered to discharge troops or cargo when the boats reach
boats that we will not include here. Any basic text on sailing will
shore. They also include varioLls types of control boats that look
usually contclin a section on sailboat nomenclature, which can be
like traditional powerboats and other specialized types of craft sllch
relerrcd to if the need arises.
as hovercrJft and tracked amphibians that cnn swim ashore and
then climb the bench to discharge their troops and cnrgo inhmd.