cant find original prop. what to go to?

[soshad]

2001 merc 150 xr6 on walleye boat. originally was solas amita 3x14.8x19p. cant find that prop anymore so my buddy got me a michigan wheel 14.5 size. now i get more speed but worse hole shot, ventilates on sharp turns tubing, and terrible in rough water with bow slap and dragging stern. should i go with another amita in a 3x141/2x19. i was told even though the same size, the amita has different rake and cup than the mi wheel prop. thought about amita 4 blade but would i have to go 141/4 dia.?

 

[Doh]

Yes you are dealing with a Cup issue mostly. If you have a Jack Plate, it might not run as high as the Solas did. If not just drop the motor 1 hole for the Venting problems.

There is much more to Props than Pitch and Diameter. But those are the Keys, find one that hits Max RPM with a light to normal load. Then start dealing with Rake and Cup. A Prop Shop can add Cup, but Rake is pretty much set.

After Hitting Max RPM, then work on.

Is the Stern High? Does it Hang in the corners, Hole Shot, Bow Lift. Some of these can be attended with Motor Height, adding cup.

 

[harringtondav]

Dialing in a prop can be frustrating. The rule of thumb holds well: One in of pitch change = 200 rpm change at wide open throttle (WOT) So reducing pitch by 1" gives a better hole shot, but robs top end speed.

Since you are using the same prop pitch and close diameter, blade shape seems to the be issue. Fixing that is a trial and error activity. Some prop shops will give you a loaner to help you get dialed in.

 

[Sea Rider]

Need to tach that motor at full throttle, assume the combo doesn't count with a tach, right ? Top speed is relative, wot rpm is all. Motor needs to work indide its min-max wot rpm range factory stated. Ideal middle to max wot rpm range, although max is preffered as achieves a faster hole shot with slight top end speed decrease.

Is motor experiencing prop aeration on flat calm water cond at straight water courses while at full throttle ? If not, all those described isues are due to motor sitting way high on transom, see if can lower it a bit till those conditions are fully cancelled out. That's why it's imperative to fine tune the motor/transom height for each motor's prop to achieve the best prop thrust on all water cond...

Happy Boating

 

[QBhoy]

Hi
As you will know and some have said..you really need to do a bit of experimenting, but I can tell you that I had a ring 18 with this engine on it and a 200 black max before that with likely the same ratio of gearbox. That ran a 23” laser 2 very well. I could easily have ran a 25” I’m sure.
No doubt the ring 18 is a real serious performance hull and used as race boats back in the day (with foot throttle and ballast tank in the bow), but I’d imagine you should certainly be able to turn a 19-21” easily with that set up. Stick to the well known merc props like a laser 2 or tempest and similar and see how you get on.

 

[soshad]

the only time it ventilates is not staying on plane in big waves and pushing hard up a wave, or turning hard when tubing. again not totally on plane but pushing hard. this boat is 19 yrs old and kicked butt with my old solas amita. just not happy with this other brand prop. i'll talk to perfect wheel here and try to get a couple props to try.

 

[Faztbullet]

Use the 14.5 x19 ….

 

[Sea Rider]

If you wot test 2 different brand props with equal pitch both props will dial different RPM...

Happy Boating