Jean-Francois:
My boat came from the factory with a 1 1/2" ID marine exhaust hose. Due
to signs of deterioration, I replaced it last year with a 1 1/2" ID
marine grade hard-wall exhaust hose. My engine is a Yanmar 2GMF and
works fine...it is nnow almost 30 years old.
While a 2" ID hose might be recommended, I don't believe your engine
will be harmed with the 1 1/2" ID hose. I am not switching up to the
larger hose.
Bob Abbott
AZURA
C&C 32 - 84
Halifax, N.S.
On 2013/08/22 6:17 PM, Jean-Francois J Rivard wrote:
Good afternoon gents,
I'm the new kid on the block. I purchased Steven Thorne's 34+ about 6
weeks ago and my family an I are enjoying the boat tremendously. I've
also been busy waxing and cleaning as well as fixing a bunch of little
things that needed attention.
My question is : Is it really such a bad idea to replace the original
1 1/2 ID exhaust hose with an identical hose? (And not going to 2" as
per the " current school of thought" )
Prior to purchase, The surveyor noted hairline cracks at the loop
before discharge with some evidence of very minor leaks. I finally got
around to disconnecting it and wrestling it out of the boat. It
appears to be original with and internal diameter of 1.5 inch and 12
feet in length. I checked with my mechanic to see if he had one on
hand and he scolded me for even considering replacing it with another
1.5 inch diameter instead of the "Prescribed" 2 inches stating that I
was killing the engine with excessive back pressure.
The thing is: This boat is clearly designed for a 1.5 inch hose.
* The stern discharge exhaust through hull is molded as an integral
part of the hull and is 1.5 inch in diameter. ( I saw it during
the survey while the boat was out of the water).
* Also, there's no way a 2 inch diameter hose would fit between the
bottom of the fuel tank and the hull where it runs from the
muffler to the stern. To get a 2 inch hose through you'd have to
lift the tank and squeeze it back in place while compressing the
hose.
* There are no hard bends or kinks, it's a straight run to the loop
before the integrated hull discharge
The engine runs fine, the boat makes 7 knots at 2,800 rpm's or so and
get up to hull speed (about 7.5) when you give it full throttle for
while so for all appearances, it's making all the power it's supposed
to make.
All this after 23 years of "being killed" by back pressure.
I might consider reworking the exhaust situation this winter when
she's on the hard for a bottom job but for now, there's no way I'm
missing on precious weekends on the lake with the family for a very
remote possibility of an issue with this.
Am I taking such a risk?
Thanks in advance,
Francois Rivard
1990 C&C 34+ "Take Five"
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