06-09-2012, 08:20 PM
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#4
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mikeyt is currently offline
Status: Platinum Contributor
Join Date: Jul 2007
Location: Ontario
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My Year: 1996
My Model: Shabah 180
My Engine: 4.3
Thanks: 87
Thanked 579 Times in 538 Posts
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Re: Which prop?
If you are getting 82kph (50mph) out of that boat with the 4.3 you are doing very well.
Trying to achieve more top end will have it bog down badly out of the hole. I would suggest that you dont screw with it.
As DCB pointed out, check out the prop education sticky cuz a little bit of self education is always good. It's not rocket science but sometimes two similar boats with the same prop wont necessarily perform in the same manner so it can become a bit of trial & error at times.
As DougR pointed out, before you attempt to change anything you need to know what your RPM's are at WOT (wide open throttle) as the recommended range for your 4.3 is 4400 - 4800rpms at WOT. Going over the 4800 rpms causes extra wear on the engine & outdrive. Going below the 4400 rpms causes the engine to lug & work extra hard. Lowering the pitch usually lowers your top speed but improves your hole shot & mid range punch. Increasing the pitch usually does exactly the opposite. Generally a 2" change in pitch will result in a 400 rpm change. 3 blade props are generally the most efficient, 4 blade props tend to provide more 'grip' but cause some additional drag while the High 5 generally performs well but are expensive to purchase. Most members with the 4.3 run either a 19" 3 blade, a 20" 4 blade, a 21" 3blade or the High 5 prop in one of those pitches to keep it within the recommended range.
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Last edited by mikeyt; 06-09-2012 at 08:34 PM.
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