The Pacific commercial advertiser. [volume] (Honolulu, Hawaiian Islands) 1856-1888, 1870-10-08

nfHyuoUs. AuheH
Tonnage .666 tons, Ala tons
Ee,' . set
Beam - Ieet--. y Zee.
DTaf of water aft ION trial irip)..-........ 10 # p in iOnSm
ENGINES AND SCREW.
Nominal horse -.l6o horse. 50 horse
Direct acting engines.
Diameter of each cylinder .-......... 80 in.--. 90 in
Length OF l M. o
Diamater OF ou4m 9n
Pitch or progress due to one revolution. =. II 4 in IsG
Maximum steam pressure 80 lbs---. 20 lbs
Maximum revolutions of engine .:-..---l26 60
Maximum speed of piston per minute. 37S feet 800 feet
Maximum speed at those revolutions ...... III knots 8 knots
Usual steam pressure at sea.----..---.. Is lbs.--' rs lbs
Which gives speed Of piston per minute .240 feet s24 fee.
s ARS give: sip fPe Of . OF yss sf iR Rsr . aSsd d.... igg . : d ans'i iss st esS;
Consumption Of fuel per hour al 8 knots...-l0 cwt-. ocWt
1t will be seen from the figures that the Ring
dore has considerably more than double the
effective power of the Kilauea, assuming that the
boilers of each vessel are in proportion, but that
from the dimensions of the ship she cannot be
nearly double as hard to drive. The probable
comparative area of midship section of each,
supposing them both to have about the same rise
of floor and turn of bilge, is exhibited by the
following figures: Ringdoue-28 feet beam X lO4
feet draft, 2S7 feet KiEduea-A feet beam K IL
feet draft, 264 feet or very little difference,
while the RingdOpe being 80 feet longer and less
draft of water, has a great advantage at least at
GIO uiSbCA cEOONo-
The most marked contrast is observable in the
pitch of the screws and the stroke of engines of
the two boats. The Ringdore has 18 inches
stroke with IL feet 8 inches pitch the KiIauea,
&c inches stroke with IL feet pitch. so that
the pistons of the latter have to be driven at a
much greater speed than those of the Ringdoue
to obtain equal speed of the vessel. The recent
practice is in favor of a short stroke and fine
Pitch, and for high speeds with direct acting
engines a short stroke is indispensable.
On the supposition, however, that u to 8
knots is about the most economical speed for an
inter-island steamer, and taking the consumption
of fuel and work performed at this speed into
consideration, we are almost surprised to find,
by referring to the above comparative figures,
| that the engines, boilers and screw of the old
KiLauea seem to be moro efficient at a speed of 8
knots than those of the recent RingdOUe. The
coal consumed per hour on the trial trip of the
KiIauea was $50 pounds of Sydney, but this will
no doubt be reduced to six cwt. per hour when
the stokers get used to their work, against a con-
sumption of ten cwt. per hour or IS per cent.
more of Welsh coal on the RingdoUe at s knots,
at which speed the engines of the latter have
evidently not 65 per cent. more work to do. We
believe that the proportions of the vessel Ring
dore are more economical than those of the uessel
KiLauea, but at this speed the machinery of the
latter seems more economical than that of the
former. We believe also that the larger proper
tionate dimensions, area and immersion of the
KiLauea's propeller is one of the most important
aids in bringing about this result; and with a
large, deeply immersed, coarse pitched screw, the
long stroke comes into play, as the engines have
a good leverage on it.
The two screws of the Ringdore arc Grifiths,
the principle of which is first, to get rid of the
central and fore and aft lying portion of Smiths
original true screw by placing a large globe or
boss there on which the blades are fixed the
| second is to taper the blades towards the extrem-