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Let's talk transmissions...main reasons for NOT having multiple gears in a boat.

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Old 05-07-2006, 10:59 AM
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Default Re: Let's talk transmissions...main reasons for NOT having multiple gears in a boat.

Is ZF the only one that makes multi speed trannies or are there others currenty out. Does anyone have their web site. Whrere is Tyson and Ivan when you need them. Thanks Jeff

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Old 05-07-2006, 11:16 AM
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Default Re: Let's talk transmissions...main reasons for NOT having multiple gears in a boat.

I had A multiple speed transmission in my boat and I will never have another boat without one. The new boat we are building will have a 3 speed transmission. Jassman, we want to be the first boat manufacture to put 3 speeds in all our boats so I do not want to disclose who is building ours yet. I would be willing to bet that in the next few years every high performance boat will have multiple speed trans.

on another note, the trans I had in my boat never broke or had any problems but the gear ratio could have used some work, and being that we had my trans all custom designed and built I would not advise someone just trying a normal trans.

when I get back from pickwick I will add to this with some insite from real world testing

Tyson
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Old 06-11-2006, 04:35 PM
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Default Re: Let's talk transmissions...main reasons for NOT having multiple gears in a boat.

Tyson how are the results coming, I sent you an email, thanks Jeff
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Old 06-17-2006, 07:40 PM
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Default Re: Let's talk transmissions...main reasons for NOT having multiple gears in a boat.

Quote:
Originally Posted by shifter
This is Chris again, but I'm logged in under Pat's name here.

Super Termoli,

I was very careful to state things in a non offending manner, especially considering the people involved in UIM and APBA, but you pretty much hit it on the head!

I also decided not to write about the Blackhawk project, but since you brought it up and martiniboat is interested in our trannies, I'll explain the Blackhawk and a project we had to compete against it.

As you know the Blackhawk is a two speed. It is actually a planetary, so it is limited as far as ratio selection goes. It also has a lot of rotating mass, and a whole host of other problems associated with the planetary design. One such problem is that if you want to put it into a boat, the boat builder has to move the engine forward 12 inches to fit it in. Now that means the builder has to redo his hull tooling, create new cabin tooling, etc... not many builder would be happy to do that.

I really should shut up now, but this is the most important fact. Normally a boat has only one speed and no clutch. So to keep the engine from stalling, the prop has to have slip built into it. You get to keep this slip throughout the engine rpm range, so you loose across the whole range.

If you couple a trans to the engine with the same prop, you get more slip in low. In other words you can't get the power down without boiling the prop. So imagine you are in first, the prop is cavitating, the boat is going nowhere, the engine runs to redline, then you have to shift. You make the shift, but the boat speed is too slow, the ratio drop is too big, it goes into 2nd and the boat falls on it's face. Then you downshift back into first to get going and the cycle repeats.

Performance wise the 2 speed sucks, combined with the fact that it takes up a lot of room, and you have a transmission that is not worth ****. Now Mercury engineers are not transmission designers, so that was their only route to take, to use an existing planetary, and why not it is in every car- it should work.

Well it doesn't and that is why when we were asked to make a transmission to compete against the Blackhawk, we didn't use a 2 speed planetary.

We came up with a 3 speed semi-automatic transmission. Our task was to fit it in with the restraint that we couldn't move the engine 12 inches forward in the boat. It had to be less so that we could have something over the Blackhawk package.

When all was said and done, we moved it forward a whopping 1/2 inch! It works, we have never had a problem with the unit, and the prototype is here to check out. We tried it with single and dual props, all in an effort to find traction. The dual was obviously much better, but still it is lacking. More prop development is needed to take full advantage of the gearbox, but the technology was arrested because Mercury pulled the plug on the Blackhawk, and thusly the need for a competing gearbox wasn't necessary anymore and our program was dropped as well.

The other issue concerning the selling of a transmission was this mentality.
"Other boats don't have transmissions, why do I need one? I'd rather use the money to buy a bigger engine or get a fancy paint job."

Brain, If you are still interested or if you have further questions, either respond here or give us a call. Ask for Pat or myself.

Chris Weismann
949-645-4064
Weismann Marine
http://www.weismann.net
Pat or Chris, is this available at this time. I had sent an email but it sounds like you did not recieve it.Thank You. Jeff Jassby 228-216-0900.
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Old 03-13-2007, 11:35 AM
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ttt BYC what happened with the transmission, and Weismann's what is the deal on yours? cost ect.

Ernie
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Old 03-13-2007, 01:45 PM
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ok..this is in concept..actually designing it and making it work would be a different story, but how about a CVT system?? a snowmobile comes to mind, with a mechanical lockup somwhere around 2500 rpm when you really start pouring the torque to it. that would be great around the docks and no wake zones. it would also give allow the motor to ne higher in the torque curve when comming onto a plane etc..
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Old 03-13-2007, 01:51 PM
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A CVT is what I was thinking of also. There are quite a few cars coming out with them.

Ernie
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Old 03-13-2007, 08:33 PM
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I believe big yellow cat on here might have this figured out, believe he has a 1.5/1, 1.35/1, 1/1 multi gear tranny with a paddle shifter on the wheel similar to a vette z06.
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Old 03-13-2007, 09:32 PM
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If you look at all the cars with Continuously Variable Transmissions (CVTs), they are all low horsepower. It is very difficult to keep them from slipping with high torque engines. I suppose it could be done, but it would have to be huge.

Michael
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