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Prop Talk (21-5)
by Steve Horsfall
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 I
have a 2.3L Volvo Penta engine in a 1993 Excel
boat. Can I change the prop from a three- to a four-blade
propeller to achieve more power for waterskiing? Any
suggestions you have would be great.
D. Perrier
(e-mail)
To achieve the best performance for water skiing, a
four-blade propeller will work well. More importantly,
be sure to use the correct pitch, which will allow the
engine to reach its maximum rpm range (usually about
4,800-5,000 rpm at wide open throttle). Check the engine
manual to see what the manufacturer’s maximum
rpm rating is.
To get the correct size, check what your current prop
achieves, then go up or down in pitch to get to the
maximum rpm. Keep in mind that each one-inch change
to a larger pitch will lower the engine speed by about
200 rpm and each one-inch change lower in pitch will
raise the rpm by approximately the same amount.
SIZE DOES MATTER
I have a 1992 Celebrity 200 BR with a 5.0 L
V8 engine. Can you tell me what the correct propeller
is for this engine? I am currently using a 14-1/2 x
19-inch model. I am also looking for any structural
information on this boat.
J. Bastian
(Fax)
The 14-1/2 x 19-inch prop sounds like the right size.
The best way to tell is by reading the tachometer at
wide open throttle – the engine should reach a
speed of approximately 4,800 rpm (maximum). The next
size of prop (21-inch pitch) will lower the rpm by 400,
while the size smaller (17-inch) will raise the rpm
by about 400 rpm. It's important to stay as close to
this 4,800 maximum as possible. The only specifications
I have for this boat are as follows: Length: 19’7”,
beam: 8’6”, draft (drive up): 18”,
draft (drive down): 35”, weight: 2,975 lbs, deadrise:
19 degrees, fuel capacity: 151 L.
SHIFTING ISSUE
I own a 1989 Doral Monticello with twin 4.3
L King Cobras with the 262 package. I recently had the
port and starboard shifter cables replaced, which were
stiff and it was difficult to shift in forward and reverse.
When I got the boat back, the shifting was a little
easier but not as much as I had hoped for. It was still
stiff shifting into reverse.
Since I have got the boat back, anytime I put the port
engine under load in forward gear the engine coughs,
sputters and the rpm drops. It only does this when the
port engine has warmed up after approximately 10 minutes.
Prior to warming up, the engine runs fine. When the
port shifter is in neutral and I increase the power,
the engine roars to life and runs smooth. Could it be
that the shifter cable on the port engine was installed
incorrectly or is it possible that fuel entered the
carb and or filter from being trailered? I have fuel
water separators that I changed in the spring.
The guy that installed the cables says that my engine
has picked up water and that I should change my filters.
I have my doubts. Any Idea?
S. Tedford
(e-mail)
Water in the fuel usually shows up as a problem at mid-range
to higher rpm, so I doubt that is the problem. I suspect
the problem may be related to the shift cable adjustment
in relation to the ignition interrupter switch. This
is a sensitive adjustment and is best handled by an
experienced mechanic. An added bonus is this should
make your shifting a bit easier.
Got a question, a problem? Send inquiries to Steve
Horsfall at stephen.horsfall@sympatico.ca Fax: 905-624-6764.
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