Vincent T5AM 500cc Marine Engine
Object ID1113111
Date1944-01-01
Works No44
Accession NoIF:2016:64
StatusNot Running
Category Engine
Collection IDInternal Fire Core Collection
Made ByVincent Engineers (Stevenage) Ltd
Made InEngland
DescriptionOpposed piston lifeboat engine
LocationUnknown
ConditionFair
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History
2016-07-29

23rd August, 1945.

REPORT ON SEA TRIALS OF VINCENT H.R.D. MARINE ENGINE NO. T5AM/X/2.

Following the acceptance test carried out on 26/7/45, engine No. T5AM/X/2 was installed in the Air Sea Rescue Lifeboat No. CE.9 at the yards of Messrs. Uffa Fox, Cowes, I.O.W. Preliminary trials were run under A.I.D. observation and measurement on 3/8/45, with a 12" diameter x 8 3/4" pitch propeller over a half-mile course in the Medina River. Times for the distance were recorded by stop-watch and fuel consumption measured by time taken to consume 1/2 pint of M.T.72 petrol from a gravity tank. Engine r.p.m. were determined primarily by "Hasler" counter, secondarily by "Smith" tachometer which was found to compare accurately with the Hasler readings. Propeller r.p.m. equals 5/7 of the engine speed with the particular reduction-gear ratio employed.

At full throttle, the engine could turn the propeller at 1520 r.p.m. with a heavy increase in fuel consumption but no increase in speed over that given at 1430 r.p.m. and a stop was fitted to the throttle lever, limiting the r.p.m. to the lower figure.

Further tests were conducted over the same course on 4/8/45 and 7/8/45, on each day conditions were similar, weather being sunny and warm and water smooth although tide conditions were not precisely identical.

At the end of trials, the engine-hatch was filled with water, up to deck level and the engine was started up and run for approximately 1/4 hour, the bilge pump removing approx. 1 gal. per minute during that period.

The results are summarized in the table below, each speed being the mean of two runs opposite directions. The boat was then taken to the open sea off St. Catherine's Point to test its behaviour under rougher conditions. With a fresh breeze and a moderate sea on 9/8/45, propeller speed reached 1415 r.p.m. with the throttle setting which had previously given 1430 r.p.m. this being to some extent due to the engine running cooler than before owing to the absence of a hatch cover. At the reduced speed of 5.3 knots, the engine ran so cool that intermittent misfiring occurred, which was cured by re-setting the water-temperature control valve. Fuel consumption at this speed was measured with the engine below its correct temperature; the results recorded (not under A.I.D. observation) are given below.

The boat was then taken through a heavy swell which appeared to have no adverse effect on the running. When coasting down the slopes of long waves, the r.p.m. rose at times from 1430 to 1500 r.p.m. On 11/8/45 the boat was used to pick up a rubber dinghy and parachutes, thus simulating conditions when rescuing a ditched crew, and on all occasions the engine was restarted with ease.

Table 1
Date Engine
r.p.m.
Propeller
r.p.m.
Speed
(knots>
Time to use
1/2 pint fuel
Range with
50 gals fuel
3.8.4512148684.317m20s924
7.8.4513509655.07113m47s932
4.8.45140010005.22814m57s1019
7.8.45141510105.30214m31s1026
3.8.45174012456.0008m11s655
7.8.45174012456.2107m49s649
4.8.45201014306.8714m40s427
7.8.45201014306.9124m37s425


Table 2
Engine
r.p.m.
Propeller
r.p.m.
Estimated
speed knots
Time to use
1/2 pint fuel
Range with
50 gals fuel
198014156.025m17s480
142510185.3313m27s955

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