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Old 17 April 2004, 11:29   #11
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Have a look at this article on Mercurys website. Very helpful.

http://www.mercurymarine.com/everyth...ut_propellers6

JK, maybe it would be good to put this in the reference section of the forum. I don't know much about props, though so maybe you should check out the content first.
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Old 18 April 2004, 09:26   #12
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Quote:
Originally Posted by Pete7
Suggest you try a smaller Ali prop to get the revs up, then having found the right pitch you might want to think about S/S and keep the Ali for a spare. The boat will be faster and more responsive with the right size of prop.

There will be a gain in performance by going S/S but nothing like that gained by using the right size of prop.

Shame but just sold a S/S 17" prop that would have fitted.

Pete
Many thanks, if anyone has a 17" for a 60 Bigfoot Merc please contact, thanks for your help.
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Old 18 April 2004, 13:20   #13
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Contacted dealer who sold me the boat, he said that they had tried a bigger pitch prop (the boat was ex-demo) but found it not to be as quick at acceleration and the top speed was the same so they switched the prop back to the smaller size. He said the rev limiter would cut in if there was going to be any engine damage and as long as I didn't run at WOT for too long there would be no harm done. I'll stick with what I have for now then. Interesting article on the Mercury link though.
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Old 27 April 2004, 06:08   #14
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I have a 13 1/4" x 17" prop at the moment on a Honda BF130 on a ring 6.5m Rib.

The boat will only rev to between 3600-3800, speed 44mph. I have been advised to try a same sized prop with a 13" pitch. Owners handbook suggest a full throttle range of 5000-6000. Reading this thread that would give me a rev increase of (150-200 x 4") 800 rpm, to say 4600 rpm, should I be looking for higher revs or do you all think this may be enough.


Thanks for any comments. Steve B.
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Old 27 April 2004, 11:39   #15
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Steve thats going to be an odd size of prop to find second hand. Most common second hand sizes for Merc / Honda boxes are like 17" upwards. If you buy a new one and get it wrong then its going to get expensive.

Also there is something wrong here. A Ribtec Camel which is much heavier 6.5m will reach WOTwith 17" prop using a Honda 130. Any chance that the throttle isn't opening fully ? or the engine needs a service? worth a check before you have to start buying props. It could even be the size of the fuel line restricting the flow, but my money is on the throttle not opening fully.

Pete
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Old 27 April 2004, 11:45   #16
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Comparisons

We have just tested two identical Parker 630 ribs fitted with mercruiser 1.7 TD in Poland one with a 21" prop and one with a 23" prop. Will post some of our findings later this week when i have had chance to analyise the data in full after speaking with Andre on this forum.
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Old 27 April 2004, 12:00   #17
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Quote:
Originally Posted by Pete7
Steve thats going to be an odd size of prop to find second hand.

Also there is something wrong here. A Ribtec Camel which is much heavier 6.5m will reach WOTwith 17" prop using a Honda 130. Any chance that the throttle isn't opening fully ? or the engine needs a service? worth a check before you have to start buying props. It could even be the size of the fuel line restricting the flow, but my money is on the throttle not opening fully.

Pete
It was Steel Developments that suggested the prop size. Steel

I have one of the propulse props which i havent tried yet, was set on buying a new metal prop. I will try that on various pitches and see how i get on.

Engine has 100hrs and has been serviced twice. So discounting that maybe!

What diameter pipe should fuel line be?

Gear linkage is quite stiff so maybe routing for that and throttle cable is bad, stopping throttle from opening fully. How would I check (take engine cover off and see if throttle body turns to stops, if visible)?


Like you say the camel boats weigh alot more than my setup.

Thanks for the pointers.
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Old 27 April 2004, 12:14   #18
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Steve, think the fuel line should be 3/8ths as you need to flow 45 lph with a honda engine at WOT.

Will the engine reach full revs in neutral ? or how about looking at the engine mechanism. Should be a lever with roller and a cam. You should be able to see if its not working fully or will go further.

Steel Developements have assumed that everything else is working correctly but something isn't quite right.

Pete
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Old 27 April 2004, 12:23   #19
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Quote:
Originally Posted by Pete7
Will the engine reach full revs in neutral ?
Rather your engine than mine.
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Old 27 April 2004, 13:00   #20
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Quote:
Originally Posted by steedthrust
I have a 13 1/4" x 17" prop at the moment on a Honda BF130 on a ring 6.5m Rib.

The boat will only rev to between 3600-3800, speed 44mph. . Steve B.
The Honda Formula 4 Stroke race boats, which are a Ring 21 Sportscruiser use the 130hp Honda, and they ran around 49mph!
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