Correct prop size?

I dont know why Delta would reccomend these props they are not well suited for ski applications...especislly if your alreaduy to high in rpm....agsin as someone pointed out it is all dependsnt on application if you are just skiing, not adding a bunch of weight on a DD SN (I dont know what a NWZ is) then a 422, 654, 668 is the best Option.... call Correct Craft!!! they have done all the testing..... if your adding weight then maybe a 1475

Those 2 props would allow the gt40 to spin up past 5500rpm, and probably scrub ~3mph. (This is assuming there is no rev limiter on the gt40, I have heard conflicting info on this). That was my experience with the similar 1868. Not good choices for all around use, but good for big loads.

Delta's advice in the past has been mildly interesting... be aware that they don't actually test many (any?) of the props themselves. Their data is collected from customers, with wildly ranging applications (hulls, loads, engines) in varying state of tunes (accurate tachs and gps verified speeds, I'm sure)... so consider the accuracy of the information vs what you typically get on this website... Even Acme's advice hasn't been spot on as of late.

Well v-drives (wakeboard boats) do (mostly) run 1-1/8" shafts, yes... but so do some cc dd's- most notably the python boats. The 13.5x16 (1-1/8") props work great as weighted/pulling props on those, the 13.5x17.5 versions are good all around props.

I run a 3-blade (1442) on my 1.23 NWZ and generally prefer it to the 4-blade (422) that I use as a backup. The 470 is still here on the shelf, the 1868 and 654 were not well suited for how i use the boat. The 668 and oj 13x15.5 XMP work good on the 6L 196, and have heard they're good options on things like the gt40 176, repowered (6L) Bfn's, etc. My NWZ couldn't pull either 5k rpm, which is about where it wants to turn. The 1490 may be an alternative for some of those applications, as would the new 3098 3-blade.

644 and 536 are 1-1/8" props. Sounds like you have done a lot more testing, personally, than I have, PROPGUY.

Bottom line is if you have a SN direct drive 1.23:1 trans the 422, 668 or 654 are the best options per Corrrct Craft and 1000s of correct craft owners promo guys tournament skiers etc its that simple.

Anyone ever run this? 1490 13.25x15.5 0.060 cup

I love the bigger diameter that the 1442 has, I'd just like it with 4 blades better!

The 654 has its place but it is not amongst my favorites for a HO NWZ. The expected use (all around, weighted for boarding, huge show ski loads, etc) plays a large part in prop selection, as does altitude. 422 and 224 are both good all-around options that should keep revs around 5000 at reasonable altitudes. Everything in the 15" pitch range will increase revs by ~200rpm, which is a little past the hp peak of a stock HO/GT40. The 1442/470/654 are good options if you either have a little more cam, or are willing to give up a little up top for some more low end pull. 4-blades should handle larger loads better if you're heavily weighted but the 3-blade Acme's are real, real close behind (and are more efficient up top). I do not care for the 668 on the NWZ hull but it could potentially be a decent option on a faster hull (like an '89). It does work well on the 6L 196's.

I copied all the 1" RH props from the ACME site and put them in a spreadsheet to compare and filter if anyone's interested in looking at them.

I've been trying to figure out where to go with a prop on our 95 Ski as well. Currenly have a 1442 that needs a little refurb. We've ran the 654 and 1442. I have a 422 on our sport but I've never ran it on the ski. I like the 1442 numbers a lot but I'm not a 3-blade fan...still prefer the 4's I think.

ACME Prop Comparison Sheet with filters

Also, I think we're running 46-48 5k on the tach with the 1442. 13.25x15     0.090 cup 3 blade

The 224 wont change much, it is only .5 a inch bigger in diameter, but less cup. Your splitting hairs here. If you wanna lower the rpms a bit go to a 668 it has more cup. But it will only lower them about 50 rpm if you want more than that you have to add more pitch, you get about 300 rpm per inch of pitch. but more pich may hurt your off the line pulling.

PROPGUY wrote: Go with the 422 it is the best choice for this application. Some guys prefer a 654 or 668 but not most.

Thanks, that's by far the more popular recommendation and with more research the prop I'll end up getting. There's a few more little demons I have to chase in the ol' girl first, but the list is getting smaller all the time. With any luck I'll have the new prop on and be able to actually test it a few times before the dreaded cold sets in.

Then again, I have a nice selection of wetsuits......

TRBenj wrote: 224 is 13x15.5, .090

Guess I can't read too good today

224 is 13x15.5, .090

I started with the 14 / 16 OJ 4 blade and my spare was the 14/16 3 blade OJ.   Like you I was not happy with the RPM of my GT40 at 30 MPH and those props had noise at various speeds. Almost a howl type noise.   Switching to the Acme at Tim's advice was a solid move. My RPM at 30 MPH is around 3,200 now so cruise speed RPM is much better. Top speed improved a little and it pulls great out of the hole with no more noise at any RPM.
My shaft is a 1" shaft the prop is a 224.   I would like to try a 422 some day but have not purchased or borrowed one yet.   I bought my 224 from TIm specifically to lower my RPM at cruise speed and have been quite happy with it although due to an accident I had to rebuild it and it is not quite the same after the rebuild.

I think it says OJ upside down and backwards, unless you rotate the prop then it will just say OJ

gt40KS wrote: I had no idea the older props were cast - I had been used to dealing with props that were forged

Fill me in.