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Old 20-07-2019, 08:18   #16
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Join Date: Aug 2016
Location: Vancouver BC
Boat: Hunter 466
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Re: Propeller pitch

Quote:
Originally Posted by Compass790 View Post
Just noticed in post #1 OP is confusing degrees with inches of pitch. When vic prop calc says your pitch should be 22" thats not 22 degrees . It means in one rotation of the prop it drives the boat forward 22" ( assuming no slippage). Is your max prop marked in degrees or inches of pitch? I'd assume inches of pitch.
No argument with kenbo saying EGT is better load indicator but doubt OP has one. Also note the boat has been going since 2003 overpropped so it's unlikely to die in the next 2 years
Oops again... that 22" was a hurried typo, it should have read 22 degrees.

Vicprop calculator suggested 19" 3 blade prop at a pitch of 11.8"... which for an 18" 3 blade prop corresponds to pitch 13.3".. and from the maxProp manual (Fig 1) corresponds to a blade angle of about 22 degrees.
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Old 20-07-2019, 08:25   #17
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Re: Propeller pitch

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Originally Posted by Compass790 View Post
How many hours on the engine? Maybe the injectors just got dirty or worn with time, they don't last forever. Best thing you can do to help injectors AFAIK is feed them clean dry fuel. But yes you need feedback from another 4jh3-te owner
Leaving it to next haulout doesn't sound too bad to me but some engine manufacturers wont honour the warranty if you are over-propped. Good idea to be a couple of hundred rpm below max as you said you would do probably. If the coolant temp & oil pressure & temp is ok you can't be overloading it too badly.
The problem for us being overpropped is we cant get to max hp in the rev range so we get drastically slowed in a headwind & sea but I'm guessing you still have adequate power with that size engine.
I'm not at the boat right now, but the engine hours are not that high at all. Sadly we don't use the boat as much as we would like to.. waiting for someone to retire first! But I do recall the technician who serviced the injectors mentioning that he was surprised by the poor state of the injectors with the low engine hours.

My guess is that because the PO had the boat out in a rental pool for a year before we purchased it, there had been some poor fuel in the tank at some point.

I had the fuel "polished" prior to the injector service and the fuel and tank were in very good shape in his opinion.... so I have been "good" to the engine from a perspective of fuel. But I was just not running the engine hard enough.
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Old 20-07-2019, 08:40   #18
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Re: Propeller pitch

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Originally Posted by patmvcr View Post
I'm not at the boat right now, but the engine hours are not that high at all. Sadly we don't use the boat as much as we would like to.. waiting for someone to retire first! But I do recall the technician who serviced the injectors mentioning that he was surprised by the poor state of the injectors with the low engine hours.

My guess is that because the PO had the boat out in a rental pool for a year before we purchased it, there had been some poor fuel in the tank at some point.

I had the fuel "polished" prior to the injector service and the fuel and tank were in very good shape in his opinion.... so I have been "good" to the engine from a perspective of fuel. But I was just not running the engine hard enough.
You were over propped, that's why your injectors were in need of service. If you pull your head I would suspect the valves would look older than the hours would indicate. I'm not saying you should do that, just re-pitch the prop and run the engine hard, it should clean things up a bit.

22 degrees sounds right based on the rpm attained vs target.
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Old 20-07-2019, 14:01   #19
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Boat: Compass 790 , 7.9 metres or 26 ft
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Re: Propeller pitch

Quote:
Originally Posted by patmvcr View Post
Oops again... that 22" was a hurried typo, it should have read 22 degrees.

Vicprop calculator suggested 19" 3 blade prop at a pitch of 11.8"... which for an 18" 3 blade prop corresponds to pitch 13.3".. and from the maxProp manual (Fig 1) corresponds to a blade angle of about 22 degrees.
Ok thanks for explanation. Useful to me as I looked up the maxprop manual & now I have an angle to try to attain when I repitch our non-adjustable folding prop ( using heat & leverage ) rather than trying to work out pitch.
Did think 22" pitch sounded more like a planing speedboat pitch.
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