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Old 06 April 2008, 15:55   #11
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I don't think you are pulling nearly enough revs.

Like you said, maybe the tacho could be out. If you think that's a possibility, best to get it checked out rather than risk over revving.

Does not sound right though, so if it were me, I'd take it back if you bought it from a company as opposed to private.

They should at least be able to attach it to the computer and see what it is running at. If the tacho is correct, I would have thought there is definitely something wrong.

good luck!
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Old 07 April 2008, 15:53   #12
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There is normally a switch on the back of the tacho that you set for either 3/4 or 6 cylinder engines.

It may be this needs setting correctly.
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Old 07 April 2008, 16:00   #13
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Tony, I assume you are trimming out to get full speed?

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Old 07 April 2008, 16:55   #14
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Hello,

A french ribs fan wich have a Tornado 580 with a 150 etec tried a lot of prop.

You can see the results her :http://img412.imageshack.us/img412/6...cesjpegiy6.jpg

He talk about it here
http://pneuboat.com/serv-bibl/module....php?id=207536

I'm sorry, it's in french but tou can find few ideas, i think.

Antoine
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Old 07 April 2008, 17:06   #15
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Try This: http://babelfish.altavista.com/babelfish/tr

might make things a little clearer.
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Old 07 April 2008, 17:18   #16
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Great!

The first day:

First assembly which I will name "race": height + 6-7 cm (driving shift +3 cm), Propeller Rebel stainless: 14.3/4 X 23: The boat seems very on-motorized, it has a very unstable behavior that I never knew to him with the 115 Ficht, the trim is practically not exploitable! The perfs are on the other hand époustouflantes in the low modes, 30 KT to 2500 T, one pushed it up to 48 KT for hardly more 4000T... but beyond that, it seemed ingérable and dangerous! I was thus a little depity of the nonhomogeneity of the ensemble..et especially I did not recognize my hull at all that I know so sure and effective.....

Second assembly: even propeller, even shift, but height brought back to + 4-5 cm the behavior of the unit very clearly improved, that always pushes very extremely, but the hull is much more stable and remains.... the push well flat is objectively phenomenal, I already used ribs which take more than 50 KT, but none had given me this feeling of "fulgurance", the 0-40KT is reached in a few seconds and less 50m I think! Side perfs: 32 KT to 3000 T, 42 KT to 4000 T, but there the boat remain well on line and very stable up to 45-46 KT, then, the hull is on a wire, it is very unstable, one pushes until practically 50 KT and approximately 4600-4700 T with the max, trim positive! It is thus much better, but very perfectible.....il remains 1000T under the cap and still a hair of instability to try to recover... if the hull (of a SR of less 6m...) to little support such dash speeds without stumbling?


New test:

Assembly +4-5 cm (not of change thus...), but this time with a very different propeller, more dedicated at the speed 14 3/4 X 21 Viper stainless: The behavior of the boat is very different as of the "setting in catch from the engine", paradoxically, whereas the step decreased one feels much less the important couple of the engine... dans trés low the modes (- of 2000 T), the nose of the boat is raised much more and the unit is much less "fluid"..... The perfs are very in withdrawal, one is more than to 25 KT to 3000 T and hardly 32 KT to 4000 T (against 42 with the 23 with the same mode!!)..la dash speed is it also penalized with 46 KT and always of the instability, which appears there besides rather, towards 44 KT! 5200 T on the other hand are reached (one took from 300 to 400 T) what was partly the required goal... mais the boat is less pleasant, less powerful (not more nervous of the whole!) in all the compartments, and especially less stable! "very basic" assembly, one descends the engine from a hole is: +2-3 cm with return to 14 3/4 X 23 Rebel of the departure: One finds a more pleasant unit, with an enormous couple in the low modes while leaving the hull very flat, a kick in the ass chabalesque, and perfs nearly identical to the first tests taking into account the water level and different conditions... soit 30 KT with 3000T, 40 KT to 4000 T and especially a concrete profit of stability à.fond since the boat remains very stable up to 48 KT (against 45-46 before...) what will be besides its dash speed for approximately 4700 T!

I hope it will help you...

Antoine
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Old 08 April 2008, 03:22   #17
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Quote:
Originally Posted by antoine View Post
Great!

The first day:

First assembly which I will name "race": height + 6-7 cm (driving shift +3 cm), Propeller Rebel stainless: 14.3/4 X 23: The boat seems very on-motorized, it has a very unstable behavior that I never knew to him with the 115 Ficht, the trim is practically not exploitable! The perfs are on the other hand époustouflantes in the low modes, 30 KT to 2500 T, one pushed it up to 48 KT for hardly more 4000T... but beyond that, it seemed ingérable and dangerous! I was thus a little depity of the nonhomogeneity of the ensemble..et especially I did not recognize my hull at all that I know so sure and effective.....

Second assembly: even propeller, even shift, but height brought back to + 4-5 cm the behavior of the unit very clearly improved, that always pushes very extremely, but the hull is much more stable and remains.... the push well flat is objectively phenomenal, I already used ribs which take more than 50 KT, but none had given me this feeling of "fulgurance", the 0-40KT is reached in a few seconds and less 50m I think! Side perfs: 32 KT to 3000 T, 42 KT to 4000 T, but there the boat remain well on line and very stable up to 45-46 KT, then, the hull is on a wire, it is very unstable, one pushes until practically 50 KT and approximately 4600-4700 T with the max, trim positive! It is thus much better, but very perfectible.....il remains 1000T under the cap and still a hair of instability to try to recover... if the hull (of a SR of less 6m...) to little support such dash speeds without stumbling?


New test:

Assembly +4-5 cm (not of change thus...), but this time with a very different propeller, more dedicated at the speed 14 3/4 X 21 Viper stainless: The behavior of the boat is very different as of the "setting in catch from the engine", paradoxically, whereas the step decreased one feels much less the important couple of the engine... dans trés low the modes (- of 2000 T), the nose of the boat is raised much more and the unit is much less "fluid"..... The perfs are very in withdrawal, one is more than to 25 KT to 3000 T and hardly 32 KT to 4000 T (against 42 with the 23 with the same mode!!)..la dash speed is it also penalized with 46 KT and always of the instability, which appears there besides rather, towards 44 KT! 5200 T on the other hand are reached (one took from 300 to 400 T) what was partly the required goal... mais the boat is less pleasant, less powerful (not more nervous of the whole!) in all the compartments, and especially less stable! "very basic" assembly, one descends the engine from a hole is: +2-3 cm with return to 14 3/4 X 23 Rebel of the departure: One finds a more pleasant unit, with an enormous couple in the low modes while leaving the hull very flat, a kick in the ass chabalesque, and perfs nearly identical to the first tests taking into account the water level and different conditions... soit 30 KT with 3000T, 40 KT to 4000 T and especially a concrete profit of stability à.fond since the boat remains very stable up to 48 KT (against 45-46 before...) what will be besides its dash speed for approximately 4700 T!

I hope it will help you...

Antoine
Yes thats much clearer
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Old 09 April 2008, 14:47   #18
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I had a Ribcraft 5.85 with a 175hp Ficht, which is basically the same engine as the 150. Initially I had a 20 inch prop on it. I couldn't get more than 4750rpm & low speed manouvering was a pain. I swapped it for a 19" & the difference was huge. 5500rpm, docile low speed response ( we used it as a dive boat so needed low speed for picking up divers) & 47kn top speed. All at around 4gph@30kn cruising.
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Old 10 April 2008, 05:27   #19
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Tested last weekend on the 20 pitch prop and got 4400 WOT. GPS kindly packed up so I have no idea how fast we were going.

The boat gt onto the plane quickly but cavitated seriously in tight turns. Not sure if this is a clue.

Plan for this weekend is to fix the GPS and test with 19 and 20 props.

We also are going to visit the issue of engine height on the trasom.

Thanks to all.

Tony.
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Old 10 April 2008, 13:52   #20
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Quote:
Originally Posted by JABS View Post
Tested last weekend on the 20 pitch prop and got 4400 WOT. GPS kindly packed up so I have no idea how fast we were going.

The boat gt onto the plane quickly but cavitated seriously in tight turns. Not sure if this is a clue.

Plan for this weekend is to fix the GPS and test with 19 and 20 props.

We also are going to visit the issue of engine height on the trasom.

Thanks to all.

Tony.

The prop caviteted with the engine trimmed in or out?
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