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Old 13 March 2007, 06:28   #1
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Why don't RIBs have gearsticks?

or an overdrive button for economy?
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Old 13 March 2007, 06:42   #2
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the drag of water on a hull makes it not work well at all on most hulls.
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Old 13 March 2007, 07:02   #3
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So maybe a big torquey diesel on a stepped hull?
Does anyone use gears or a cvt transmission like my mum's old DAF?
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Old 13 March 2007, 07:48   #4
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or an overdrive button for economy?
Like this one ?

http://www.stepdrive.co.uk/stepdrive.htm

Pete
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Old 13 March 2007, 09:14   #5
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Getting a variable pitched prop would be the same as gears wouldn't it?
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Old 13 March 2007, 11:51   #6
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Surface drives sometimes have 2 speed gearboxes - they fir them to Sunseekers for instance. Class 1 boats also have them, I think they are limited to 2 or 3 gears now.
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Old 13 March 2007, 16:09   #7
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Getting a variable pitched prop would be the same as gears wouldn't it?
Kinda similar but the variable pitched prop would be better because at lower speeds the low pitch would hold the water better. Not to take anything away from the gearbox cos I'd like one if it was available but I've seen me open the throttle wide on the back of a wave at about 15mph and been aware that the props are showing sign of breaking away. With the extra torque the gearbox would apply to the props, they may well let go.

I'd actually like the gearbox to change up at higher speed rather than change down at lower speed. If the boat was set up with a fine(ish) pitch prop so as to give good performance in the lower and mid range, then when up to cruising speed it would change up sorta like an overdrive. A small disadvantge would be the low pitch prop not being quite so efficient at higher speeds but overall it could be very satisfactory.
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Old 13 March 2007, 18:01   #8
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http://fbdesign.it/a38rib.php

Take a look at this!
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Old 13 March 2007, 18:42   #9
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I'm sure I heard of an outboard from MANY years ago that used a CVT setup-but the CVT was effectively the throttle as the engine RPM stayed constant.

I think it was one of the marine engineers from Iboats.com that was talking about it-and it wasn't April 1st.
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Old 13 March 2007, 18:54   #10
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Apart from lawn mowers , surely outboards are one of the last class of engines that do not have gears, I've wondered about this for ages, bikes have them and like outboards have rediculous rpm ranges, but we dont?, and why not ? Seems strange to me ?? Ok it means a clutch mechanism and all that but tractors have had amazing shift mechanisms under power since the 70's? .. the tech isnt new, is it the cost ?
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