CVT transmissions, why not in boats?

(tidalwake0504) · (tidalwake0504) **Join Date: Oct 2004** 07-25-2005, 5:32 PM

If you don't already know what a CVT Transmission is look here.http://auto.howstuffworks.com/transmission2.htm
Now tell me why there isn't one on my boat?

(ss1234) · (ss1234) **Join Date: Jul 2005** 07-25-2005, 6:12 PM

Ok, I give up. Why isn't there one on your boat......no place for the shift lever.??

Adding another lever would really get the folks on that other post spun up that are talking about why the driver / throttle is on the right side of the boat. Should I throttle with my right and shift with left or shift right, throttle left?....oh crap, how am I going to steer this thing...?????

tommcat 07-25-2005, 6:27 PM

many, many reasons. mostly that there is simply no need to change gear ratios on a boat.
another big one is that they wouldnt hold up to the power of a V-8 very well

bruky__ 07-25-2005, 6:49 PM

They should invent a boat with inferior hull design with a need for 2400 lbs of ballast, and use a 2 speed to get it on plane. It'd make perfect sense.

(wakeeater) · (wakeeater) **Join Date: May 2002** 07-25-2005, 7:04 PM

i drove a boat with a turbo 400 tranny yesterday but thats a little different. but running a big block driven v drive day cruiser through the gears is pretty sick

(peter_c) · (peter_c) **Join Date: Sep 2001** 07-25-2005, 10:57 PM

Ummm...MB has a two speed trans as an option in their boats.

(laptom) · (laptom) **Join Date: Apr 2002** 07-26-2005, 3:28 AM

Steve, you don't need a shift lever for a CVT. The transmission is a continue variable transmission and doesn't use fix gears. I think it could work well on a boat, but like Tom said. There is no really need for a gear ratio change on a boat.

(kingskrew) · (kingskrew) **Join Date: May 2004** 07-26-2005, 9:52 AM

From what I understand, gearing isnt the only issue. If you were to run a geared tranny or a cvt, then the prop would become the wrong pitch to match the engine torque/rpm.

-Steve

jamescoop 07-30-2005, 4:23 PM

Matching the enigne torque and rpm is what a transmission does. Putting a cvt to a motor in a boat would be a great idea. It would definately help with faster acceletration/top end, just like in a car. The problem would be that so far they dont have CVT transmssions to mate with the 8 cylinder engines, as the belts cannot yet support the torque and hp like a normal geared transmisison can.
As for changine the gear ratio on a boat, why not? In a car the gear ratio helps with acceleration and high speed. You have higher gears for a quicker acceleration and lower gears for a high top speed. In a boat it would be the same thing, the faster you accelerate is determined by how fast you can spin the prop from a start, then the tranny would slowly shift (in the CVT case you wouldnt notice it shifting) so that the porp could spin faster and faster while the enigne maintains lower rpms.

(big_ed_x2) · (big_ed_x2) **Join Date: Jul 2004** 08-01-2005, 10:29 AM

big problem is too much resistance in the water.Cars have brakes,boats do not...there is a reason for that.

you need a different pitch props not different gear ratios to make the theory work.

tigejohn21i 08-01-2005, 12:54 PM

I thought at first you would need a variable pitch prop. But then, if you think about it, my car doesn't need variable sized tires. So, if a gear change would increase the prop rpm while providing less low end torgue, i think the boat would go faster at top end. Of course, I have absolutely no idea what I'm talking about :-)

(big_ed_x2) · (big_ed_x2) **Join Date: Jul 2004** 08-01-2005, 1:10 PM

quote:
Cars have brakes,boats do not...there is a reason for that.