Propeller performance help

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whitecrystal1

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exMember
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Dec 9, 2006
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24497
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I just installed my new set of Bravo III SS props after having them polished. I bought both props on Ebay in separate auctions as new old stock. After going for a ride today I am unimpressed with the performance with them. See test results below

My boat has a 2001 5.7L 260hp engine in it and with the original props it runs around 4,400 to 4,500rpms at full throttle and is running 47.5mph (all speeds are by GPS). At 3,000rpm I run real close to 30mph if not right at 30 and at 3,600rpm it's between 35/36mph. This new set is a bit different. At full throttle it's running 4,900rpms and is only going 43.4mph. At 3,600rpm I was only able to get 32mph and at 3,000rpm I was running 25mph.

These props have the same part numbers as the original props why would these not run at least closer to the same? I'm thinking these new props are underpitched for my boat, but they are labeled as a 24 pitch prop?? what gives?

Thanks
 
Maybe they are not as new as you thought, maybe they are not a matched pair, etc.

Best bet, imho, is take them to a propscan shop and get a free scan. Then you will have actual data with which to make a diagnosis...

( btw: in general, this is always a good plan, with any newly acquired prop. )
 
Pitch is only one attribute that affects the effective pitch of the prop. The cup, rake, blade material among other things will affect the performance.

I am surprised that the same manufacturer of the same part number would result in different props, however. Sounds like somebody altered something.
 
When I dealt with a prop scan shop, I was told that new props right out of the box seldom scan for pitch as advertised.
 
out of curiosity, why did you get new props? what is the wot rating of your boat (rpm and speed) and were you able to reach those numbers with the old props?
 
Bought new props because I wanted a spare set. I bought them one at a time off ebay trying to save some money. I installed them after having them polished and was going to send out my original props to have the edge of the blades cleaned up, their in pretty good shape but do have some small nicks on the edges. After testing this new set I am going to reinstall the old set for now :( I called a local prop shop and he wants me to bring both sets to him so he can take a look at them and see what would be causing the performance loss. He said my engine should be in the 4400-4800 rpm range. The original set get me to 47mph in 4400-4500rpm This new set only gets up to 43mph at 4900rpms.

The only thing I am curios is would I be wasting my time taking them to this shop because he already said that he doesn't have a prop scan... and he is a prop shop. He sounded very interested in seeing them and even wants to rework my props. He says he can get me 3-4mph out of both sets. Well at least he said to look at them he would not charge me anything.
 
Agree with all of the above and yes, IMO you are wasting your time. Computerized tuning propellers is the only way to go. The money saved in fuel will pay for the cost. The smoothness is just a great plus.
 
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