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Old 31 May 2010, 04:26   #11
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It's not blow out - the whole back of the boat goes sideways and believe me it gets your attention!

Waste of time going up 4" of pitch if you're not hitting top revs with the 15" so I don't understand how you can get the same RPM? Is the 19 a three blader and smaller diameter by any chance?

The holes in the prop are irrelevant at this speed

Is the boat porpoising at all?

Have a look to see if there is any pitting on the blades on the four blader.

Just my 2P worth!
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When a boat looks that good who needs tubes!!!
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Old 31 May 2010, 17:17   #12
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It's not blow out - the whole back of the boat goes sideways and believe me it gets your attention!

Waste of time going up 4" of pitch if you're not hitting top revs with the 15" so I don't understand how you can get the same RPM? Is the 19 a three blader and smaller diameter by any chance?

The holes in the prop are irrelevant at this speed

Is the boat porpoising at all?

Have a look to see if there is any pitting on the blades on the four blader.

Just my 2P worth!
Thanks all for your responses....props really are proving a black art to me....

Ran some trials today....the effect goes away with the 19 pitch....

The revs definately show the same /similar with both props (as posted on earliuer thread can't get my head around this)....probably inaccuracy in the gauge (?) as has been suggested....therefore, concede it may be a rev limiter, although can't find any mention of a rev limiter doing a brief internet search....perhaps someone who knows could advise.

No pitting of the prop Cookee, and as above re the revs dia of both props the same....bizarre!

Anyway, relieved it doesn't appear to be an engine fault! ALTHOUGH, it threw a brief check engine alarm "SENSOR POWER" as i came off the water Typical Cleared now and hasn't reappeared...don't have my manual to hand so not sure which sensor triggered it....anyone know off the top of their head?

Back out tomorrow....

Thanks again to all

Dan
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Old 31 May 2010, 17:27   #13
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Call me a witch .. but (in the absence of being there) I think 15" is too small for that set up and in any case what was it... 15 x what ?
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Old 01 June 2010, 06:17   #14
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Jumping back to the tacho for a minute - what flavour of merc is it? I'm thinking if it;s one of these new fangled digital things, chances of the tacho getting the wrong signal are slim (it will take the tacho reading form the crank sensor signal rather than the slightly crude but effective counting pulses form the alternator)

I just calculated the ratio of pulses for an analouge tacho set to the wrong number of poles, and the theoretically indicated revs don't add up there either assuming a rev limiter at 5700. That of course doesn't prove the "needle to pulse count" accuracy.

If you can borrow a tacho, might be worth just sanity checking yours.
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Old 01 June 2010, 08:05   #15
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Jumping back to the tacho for a minute - what flavour of merc is it? I'm thinking if it;s one of these new fangled digital things, chances of the tacho getting the wrong signal are slim (it will take the tacho reading form the crank sensor signal rather than the slightly crude but effective counting pulses form the alternator)

I just calculated the ratio of pulses for an analouge tacho set to the wrong number of poles, and the theoretically indicated revs don't add up there either assuming a rev limiter at 5700. That of course doesn't prove the "needle to pulse count" accuracy.

If you can borrow a tacho, might be worth just sanity checking yours.
Tis an Opti....150

I have a spare smartcraft which if 'd thought I would have put on...good thinking batman!

Just got back from sea....all ran fine. The POWER SENSOR alarm turned out to be a dodgy speed wheel sensor....so disabled that and all fine. Running with 19 and no probs....guess it must have been rev limiter??

Was talking to a dealer earlier who said he's never been able to get a 150 Opti near the top revs of 5700....on tacho at least....

Possibly wrong attitude, but just pleased its all okay.....need to keep the throttle back slightly with the 15 pitch....not a prob when loaded up....

Incidentally with the paddle wheel now going caput, this means that I have had to disable both the pitot and the paddle wheel sensor as well as the trim sensor which has also thrown a wobbler....will get them looked at at some point /when I next go to a dealers...fragile aren't they!

Cheers Dan
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Old 01 June 2010, 08:13   #16
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Incidentally with the paddle wheel now going caput, this means that I have had to disable both the pitot and the paddle wheel sensor as well as the trim sensor which has also thrown a wobbler....will get them looked at at some point /when I next go to a dealers...fragile aren't they!

Cheers Dan
Can you not tell the guage to read from the pitot at a lower speed ? My paddle wheel (and the depth) becomes worthless at anything over 10knots - so I have set it to switch from the paddle to pitot at 5knots .

I am pretty sure the opti rev gauges are accurate & instant ( not averaged) but with all the electrickery going on who knows !
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Old 01 June 2010, 08:30   #17
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Can you not tell the guage to read from the pitot at a lower speed ? My paddle wheel (and the depth) becomes worthless at anything over 10knots - so I have set it to switch from the paddle to pitot at 5knots

Sorry, wasn't clear....Pitot got switched off a while ago...kept throwing up check pitot and no obvious issue /blockage....got fed up and switched it off. Then the trim gauge went mental fluctuates betwen trailer and numbers (random number generator stylee ) so that got switched off....now the paddle wheel sensor has been causing alarms and the speedo to do strange things....have switched that off today and problem has gone away!

Will get them looked at when I get chance.....

D.
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Old 01 June 2010, 09:11   #18
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...Was talking to a dealer earlier who said he's never been able to get a 150 Opti near the top revs of 5700....
Mine's the same - can't get it past 5100 RPM. The DDT readout confirms this too.
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Old 02 June 2010, 03:56   #19
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Connect your GPS up to the Smartcraft and tell it to use that - paddlewheels and pitots are not that great anyway!
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Old 02 June 2010, 16:21   #20
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paddlewheels and pitots are not that great anyway!
Yes thats been my experience too
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