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Old 18 January 2012, 10:51   #11
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Country: UK - Scotland
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I've yet to get the Merc prop out the water.....

On the Suz / SR4 I pretty much did what chewy said, although the ergonomics of your throttle lever doplay an important part in the "ease of doing so" stakes.....
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Old 20 January 2012, 09:51   #12
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Quote:
we get told to keep the power on
exactly, with good reason. Tis ok with a high powered boat and responsive engines doing x amount of knots to be doing all this throttle juggling and that is a skill pwerboat racers no doubt have in spades -- but Nathan has a "moderate" engine on a sr4, as does the o.p. So when you come off the back of a wave with that you aint gonna be airborne for long and ******* about with the throttle will likely see you come down dead in the water with no forward drive to cushion the blow and it will hurt-Been to recover a guy who fractured three vertebra landing like that in a 5.85 ribcraft/75 o/b. Its easier to mend the o/b (and I have never broken one or seen a leisure o/b broken thru over-revving when airborne) than it was his back. I also like to have positive exhaust pressure in the leg on landing thank you.
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Old 21 January 2012, 04:55   #13
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Originally Posted by wavelength View Post
exactly, with good reason. Tis ok with a high powered boat and responsive engines doing x amount of knots to be doing all this throttle juggling and that is a skill pwerboat racers no doubt have in spades -- but Nathan has a "moderate" engine on a sr4, as does the o.p. So when you come off the back of a wave with that you aint gonna be airborne for long and ******* about with the throttle will likely see you come down dead in the water with no forward drive to cushion the blow and it will hurt-Been to recover a guy who fractured three vertebra landing like that in a 5.85 ribcraft/75 o/b. Its easier to mend the o/b (and I have never broken one or seen a leisure o/b broken thru over-revving when airborne) than it was his back. I also like to have positive exhaust pressure in the leg on landing thank you.
I have driven quite a few smaller engined boats as well, and I would say that whilst the likelihood of damage is reduced it will still reduce the life of any engine to over rev it. The guy who "fractured three vertebra" would have done so on landing and no amount of throttle would have prevented that and to suggest anything else would IMHO be wrong. The exhaust in an outboard faces backwards, and despite coming back down with the boat almost vertical after a particularly big jump in extreme conditions I have never yet managed to stall an engine.

Having said that if we talking about tiny little jumps for a fraction of a second then I can see how it would be less of a problem, but if you're going out in big waves I really believe you need to learn some throttle control - it's not that hard!
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Old 22 January 2012, 06:26   #14
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Does the same technique apply for jetboats? Too much time in the air will empty the jet and presumably lead to periods of no drive whilst it re primes. I imagine the delay in picking up the drive will be longer than with a prop?

On my project I have had to build a throttle lever setup that has a fly by wire sender unit that controls the throttle. there is very little resistance on the lever, so I have put a one way hydraulic damper on the mechanism that allows throttle to be taken off easily, but doesn't allow it to be opened up too quickly.
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Old 22 January 2012, 08:31   #15
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I would reckon being airborne at full throttle is likely to do some drivetrain damage eventually.
When you've got a thousand hp swinging large bronze propellers through vee drives and gearboxes there is likely to be some kind of snatch when the prop bites again

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