Why don't boats have multi-speed transmissions?
#2
I have seen videos and threads on high performance boats with 2 or 3 speed transmissions. They seem to be for slowing the high pitch props down around docks and idling speeds, and keeping a "peaky" race engine in the power band (I'm certainly no expert, just what I've seen and read).
For most boats, prop slip will allow a boat to come on plane and cruise at lower speeds, negating the need for a multiple speed transmission. If the boat will turn the correct wot rpms and come on plane reasonably, then why would you need a transmission?
For most boats, prop slip will allow a boat to come on plane and cruise at lower speeds, negating the need for a multiple speed transmission. If the boat will turn the correct wot rpms and come on plane reasonably, then why would you need a transmission?
#3
I've kinda figured that you tune a engine and prop combo for top speed, and prop slip acts like a torque converter to a degree. I was curious if there's been much experimentation with it. I guess in a high enough performance setup you'd need a gear reduction for slower maneuvering.
My non boat owning friends always ask me this question but I never had a solid explanation.
My non boat owning friends always ask me this question but I never had a solid explanation.
#4
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Several years ago it was all the rage, racers used them to gear down for cornering and acceleration out of the corners, but I think they proved too "complicated" to use properly and just another complex item to fail under extreme race conditions. Some of the current racers may weigh in on this, but I think they are used anymore, and some governing bodies may have outlawed them.
#5
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Have one...21 Eliminator Daytona, factory B/B turbo 400, pretty cool to drive, manual shift, really dont use low gear..but is a V-drive
http://s227.photobucket.com/user/ezs...dscsr.jpg.html
http://s227.photobucket.com/user/ezs...dscsr.jpg.html
#6
Have one...21 Eliminator Daytona, factory B/B turbo 400, pretty cool to drive, manual shift, really dont use low gear..but is a V-drive
http://s227.photobucket.com/user/ezs...dscsr.jpg.html
http://s227.photobucket.com/user/ezs...dscsr.jpg.html
I never thought about it much but any final gearing is determined by the power available and torque needed and a transmission just reduces loads until you get to that point. On a heavy boat the prop just slips up to that point like a viscous coupler.
#7
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iTrader: (6)
A car can upshift and cruise at 80 mph at under 3,000 rpm. A boat has a much greater amount of drag and needs to be near it's peak output to maintain a high speed. Shift it up and it will just keep slowing down. Usually there is enough prop slip to get the boat on plane and moving.
#8
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Back in the 80's Mercury tried it. They were designed for the heaver boats. They were junk and didn't ever work the way they were designed. B & M did a drop in replacement for the Mercury for a while. ZF did some 2 and 3 speeds for racing APBA outlawed them after about 2 years of guys racing with them. Usually only the unlimited budget teams had them. The ones from the other side of the globe. When Mercury racing came up with the #6 and guys aerated them to get slippage to get on plane that took of the problem to get a big heavy race boat on plane.
#9
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#10
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I believe JD Onken (Don's son) ran heavily modified powerglides in his 32 Skater. Not sure who has the boat now but I've seen it in the Skaterfest pics recently.