users of Acme 470

I am having an issue with my Acme 470 that I think is unique (did a search and didnt find anything) and hope that someone familiar with props could give me some insight.

I got the 470 in 2006 and have had it on my boat since then. Its a 93SN with Pro Boss GT40 with 1.23:1 trans, so its about 285HP.

The improvement in hole shot was dramatic over the stock prop which was Michigan 14X16.

But after some time I noticed that when at speeds over 36 on smooth water the nose of the boat seems to "wander". I dont know what other word to use but the direction would cycle back and forth a little bit (foot/sec) but keep the general heading the same. Now I dont have many needs to go over 36 except when barefooting which is rare, but it was concerning and I wondered if the old prop did the same thing.

I finally got around to putting the Michigan back on last week. While there certainly was less hole shot (but still plenty as any competition boat owner knows) the "wandering" stopped completely.

My theoory WAG is that the extra surface area on the Acme pushes more water therefore maybe pushing the bow down a bit more than the Michigan does and changes the handling. But I am looking to see if anyone has seen a similar problem with this prop or any other.

I really like the power of the Acme but dont like the high speed handling. Anyone have any ideas as to why it does this or how to fix it if possible?

thanks,
Rich

Thanks Todd,
If i keep the prop, maybe we can do a lake test next year. The only difference between the 470 and 1422 is 3/4 inch larger diameter. I dont THINK that would make that much difference, but I dont know for sure. Thats why I posted, hoping that someone else would have more expertise.

I have emailed this issue to ACME today and hope to hear back from them.

I have tried both the 470 and 1442. I currently have the 1442 on the boat. I haven't noticed it wandering at speed but when running 30+ mph and then I shove it down for barefoot speeds it feels like the boat jumps out of the water and rotates on the water a little. My wife doesn't notice it so it can't be that pronounced but it does do it. I figured it was just the boat talking to me saying it wanted to run. Once up to the higher speeds it tracks very straight.

Rich, thats strange- I havent noticed any wagging with my boat on any of the Acme's Ive run (422, 1442, 612, 470, cupped 470), and Ive spent a LOT of time at WOT. I can tell you that every hull is a little bit different though, so maybe youre seeing some sort of anomoly with a particular hull/prop combo. Its also true that Acme's have very little, or possibly slightly negative rake, so that will bring the nose down a touch like you suspect.

At the very least, Im glad to hear that performance while skiing is much improved. Let us know if you find out the culprit!

Most course skiers will adjust or grind rudders to have a little pull. Really helps if you drive for a skier who can lean away well.
BTW, nice color choice on your 93.