Prop for the 86.?

Would a Federal Super Cup 13x12xR1. be the right prop for my 86 stock 351 nautique? It has an unknown(because I havent pulled it off) 4 blade prop and it will only turn 4000 rpm's at 44mph and doesnt have the stuff out of the hole Id like it too. It runs about 3000 at 36 and With a skier with deecent pull behind it you have to give it a fair ammount of throttle to keep it at speed when in the cut. Thanks for the info.

I bet a 13x12 Acme would work well.

phatsat67 wrote: 4000 rpm's at 44mph and doesnt have the stuff out of the hole Id like it too. It runs about 3000 at 36

Has this been verified with GPS? I only ask because 36 mph @ 3k would be a dream. It's been shown on here it's going to cost you some $$$ to run mph>rpm on a 1:1 trans. Definitely not what I'd expect out of a stock 351 engine, not to mention on a 2001 hull.

wakeboard= acme 542 13x11.5
ski = acme 540 13x12
if your numbers are correct. im supprised you can get on a plane. your boat is probably no fun to drive and getting horrible gas millage.

Hey phatsat67!
Is that the boat with my old windshield on it? If you lean that glass back a little, you should pick up some top end!

Just kidding!

Here's a link to a neat little prop calculator: http://www.rbbi.com/folders/prop/propcalc.htm

You can work backwards to try to guess the pitch of your prop and confirm it by your observed speeds.
I played with it some with the known gear ratio (1:1) and the other known factors (observed speeds and observed rpm's). It didn't seem like 3600 rpm's and 30 mph fit right. With an assumed 13" pitch prop it calculated only 2.5% slip (which seems real low), while your 44 mph at 4400 rpm's (and, again, an assumed 13" pitch prop) yielded 10.6% slip, which sounds more realistic. I've seen info. that suggests slip for "planing runabouts" to be from 15% to 25% (a pretty big range).
As I've played with these calculators, or just done the math, it seems like most are in a slippage range of 10% (on the low side)and the high teens (on the high side). Another factor is that I think a "cupped" prop has the effect of adding maybe 2" of pitch (or something like that).
Then you gotta think the slippage is probably different at different speeds too! That makes it more fun!
64X55

Alright So I went out and pulled the castle nut off tonight and found out thats its a cupped 13x13 oj legend 4 blade prop. Too much for the boat ya think?

Whoa! phatsat67 - didn't know you were counting on a reply to bid on something (I must have skimmed too much above there). So you've got a 13x13 4 blade and the specs say you should have a 12 pitch (assume that's for 3 blade)? You didn't metion the diameter; is stock 13x12? And what is the auction for?
Additional cup will lower your rpms; but it should help all around I would think unless it's so much cup that it really takes your rpms way down. Sounds like you're wanting to get them up, right? Sorry didn't check in for a while! Maybe the auction is over by now!
My boat is just out there patiently waiting for me to get back to work on it! Probably told you before, I got my "original (correct) windshield" back in the summer, but I haven't done much lately. Winterized the engine because I had it started a couple times since spring. I could work on it some through the winter if I get myself motivated (and if I had some "spare" money for some of that really economical to buy 3/8" mahogany marine plywood). I think Pete (8122pbrainard) found some for as low as "under" $200 per sheet! What a deal, huh?!?!?!! Let's see; how many sheets do I need...
Hope you get the right prop! It's interesting; the little Dunphy X-55's came with a Michigan 12x15 cupped prop which is a pretty high pitch!

Yea We dont wakeboard behind my boat How dare you imply that haha. It gets all slalom/trick/kneeboard and jump if we had one. The practice lake we slalom on is really small and rite now with a skier you have to hold her wide open till the gate to get it to 36mph. Oh yea Im a college student soo im not looking to buy a new acme yet although im pretty sure it would work wonders. X sounds like your about ready to get that old woodie done. Thats some serious pitch man haha I bet that runs like 2000 rpms at 36 haha.

phatsat67 wrote: Oh yea Im a college student soo im not looking to buy a new acme yet although im pretty sure it would work wonders.

Obviously you're not a golfer. Ask ACME to send you a prop to test, next thing you know you'll be racking your brain on how you're going to pay for it. There is no way you'll send it back.

phatsat67 wrote: Do you think I could get pitch taken out of the OJ on my boat or have the cupping removed?

Yes, its possible. It will probably cost you $80-100 at a minumum, and very possibly more than that.

Like I said, I wouldnt spend a dime on anything other than an Acme 540. Id put the $100+ youre considering spending on another prop or a rebuild towards it, and keep saving until spring.

phatsat67 wrote: What do you mean im not a golfer haha?

It's a quote from the movie the Big Lebowski....

Yea I guess thats a super light boat. Ahh Seee ive never seen that movie so I dont know haha.

Thats pretty cool but you dont need to power turn when your outrunning everyone else haha.

One of my buddies on the ski team did a 40 mile race this year and his girlfriend was on the team footing also(bad ass chick).