Tranny Ratio of 1.23:1 - what does this mean?

[nautique_stealth]

I picked up my boat (99 Air DD) almost exactly a year ago , but I've always wondered why it only goes 37mph at 4.8/4.9k rpm. I was just at the Nautique dealer and they showed me that my trans isn't the normal 1:1 ratio, it's a 1.23:1.

They said it means I have more power out of the hole, but sacrafice top end... Does this sound right?

37mph is plenty fast for pretty much everything... except for barefooting (which I'm learning)...

So, what prop should I be running? I have a pretty good condition 422, and a 'repaired to new' 422 (that I spent $200 to repair thinking that's why I could only go 37!)

Is the 422 the best for me, and 37mph is all I can expect, or is there something better?

I use the boat for all watersports, but I mostly wakeboard/surf.

[Rick]

The ratio of the transmission does have something to do with top end and hole shot. Knowing that all Nautique boats after Mid 80s?have that transmission prop pitch and diameter is the really important thing. There is always a tradeoff between hole shot and top end. I don't know what pitch a 422 is. If its 14 then to get more speed you need to go to 16. By going to 16 you will lose some power in the hole. You just have to play with it to get it right. I'm sure someone else will chime in but rest assured you don't need to change transmissions.I would call ACME or Delta. They would be able to help you. Good luck.

[nautique_stealth]

Thanks for the input. Just googled acme 422...

Diam. x Pitch
12.50 x 15.50

Cup
.105 cup

[Rick]

Here is a link to the ACME size guide. http://www.acmemarine.com/prop-list_ski-boat.php They also have a 30 day trial. I believe Delta will also honor the trial

[Stumpie]

First off don't go back to that dealer. On a dd naut a 1:23:1 is the correct
tranny for that boat and a 1:1 is what goes in a vdrive naut.
You may want too make sure your engine is running on all cylinders
i have a 97 sp with a gt40 and get 45 mphs. I am running a 14/16 4 blade oj
prop. Also the 422 may not be the right pitch for your 99 Model. Hope this helps

[DanielC]

Are your speedometers accurate?

The 1.23 to 1 transmission turns the propeller slower, but the propeller has a higher pitch that the boat would with a 1 to 1 transmission. A higher pitch propeller turning slower is more efficient that a lower pitch propeller turning faster.

[ski4evr]

With a 380 prop you should be in the mid to high 40's. My 211 came with one and that is what I saw. switched to the 422 and now am right at 40mph at 5 K rpm. The improved pulling power is what I was after and got it with the 422.

[shag]

You should get close to 45 out of that boat.... I would check the speedo's.... The 1.23:1 was introduced to help with low end pull which it did well, with very little if any decrease in top end...

[nautique_stealth]

Thanks for all the input guys. I'm going to call Acme tomorrow and see what they have to say about a prop.

As for the speed, it's accurate. I've taken my GPS out on it.

My dad has an 02 Air (EXACT same boat). He has the 422 prop and pulls 47mph. But he thinks his is a 1:1? But maybe he's wrong after what you guys are saying.

Cylinders were all check when I bought it. Compression was great (150s).

[xlair]

Wow the amount of inaccurate information in this thread is disturbing...

First off- probably 98% of all DD nautiques from 1989 to present have the power plus 1.23:1 tranny. Only a small amount of 240hp SN's in early 90's got the 1:1.

The acme 422 is the most common prop for your boat. Someone earlier was referencing v drive props and those obviously won't fit on your boat.

Lastly your setup assuming gt-40 should pull about 45 mph top end wot. 37 mph means you either have broken speedos or something is wrong with your drivetrain.

[AirTool]

I'm sure you would notice if your hull was covered with barnacles.

Do you have any extra weight in it?

Even my top being up and 4 people and a footer doesn't slow my 206 down below 42.

Maybe your tranny is slipping.

[Lewy2001]

My dad has an 02 Air (EXACT same boat). He has the 422 prop and pulls 47mph. But he thinks his is a 1:1? But maybe he's wrong after what you guys are saying.

Cylinders were all check when I bought it. Compression was great (150s).

Acme 422 should be the right prop for that boat and get you around the 45mph mark. The 422 would have way to much pitch for a 1:1 transmission.

[Chexi]

I swear I remember getting 42-44 on that boat, with that prop, and no ballast (using GPS and speedos calibrated to GPS).

[east tx skier]

98 SN with a GT40 and a 422 (also refurbished). No trouble hitting 46 mph. Check your fuel filter. Clean the flame arrester. Or a dozen other possibilities. Unweighted, mid 40s should not be a problem.