OK, another I/O prop question!!! Please advise

ramos777 · Newbie Joined: 07 Mar 2008 Posts: 35

ok, I've done some research and I just need some help with my particular setup. I need a little extra low end power to help a weighted I/O. The boat pulls bigger people up just fine but keeping speed is a little difficult under 20 (still got young ones who need to go slower) and we really have a hard time pulling a skier up even w/out weight.

Current setup 19p SS 3-blade

I need to get this pretty quick so I found a local shop that has a Michigan Wheel 4-blade Aluminum w/ 18p.

I've read that the extra blade can account for a 1p difference but dont know exactly and I know the aluminium is not as good as SS but I'm in a time crunch and can get it for a decent price, and can upgrade to ss if it works out.

Will 1 blade and 1 degree of pitch be worth anything? Can I go to a 16p?

I think I run well below my WOT recommendations when loaded but would rather have a higher pitch for "hauling ass reasons."

Please help

InsaneGtp · Newbie Joined: 12 Jan 2008 Posts: 9

deff need more info bro... I have the same issue right now in a 21.5 ft bowrider.. Merc 5.7l

What boat / engine do you have.. what is your WOT RPM ? and what does the engine want to have for WOT, I am gonna run two props, one for waking and another if it's just me a friend cruising.. you might wanna do the same..

JUST-IN-TIME · Posted: Jun 30, 2008 8:33 pm Post subject:

you want to run WOT 85% loaded

what motor u got?

ramos777 · Newbie Joined: 07 Mar 2008 Posts: 35

I've got the Volvo 5.0 270 fuel inj engine. The recommended WOT is 5200 and I run at about 4700-4800 @ 85-80 % load

brichter14 · Addict Joined: 27 Apr 2008 Posts: 705

how do you find out your WOT

pet575 · Posted: Jul 01, 2008 11:43 am Post subject:

You're going to pick up about 200 RPM's for every inch of pitch you drop down. So, if you went down to a 18p 4 blade (if your theory on 1 blade=1p is correct) that should get you about 400 more RPM's.

Not sure if I buy that theory, but I'm not necessarily arguing it either. I have no personal experience with adding a blade and its effects. Assuming that theory is right, I would think you'd get a lot better holeshot but you are definitely going to give up some top end by going to a 18p 4 blade.

ramos777 · Newbie Joined: 07 Mar 2008 Posts: 35

What about the flex of the aluminum vs SS... am I just pissing in the wind by only going down 1p w/ an aluminum prop?

Brichter14- just run it at WOT and when you top out that is your WOT RPM

JUST-IN-TIME · Posted: Jul 01, 2008 5:17 pm Post subject:

18p 4 blade will be perfect

gx205 · Outlaw Joined: 23 May 2007 Posts: 118

I have a 5.0 volvo penta motor in my glastron, and I just went from an aluminum 3 blade 19p, to a SS 4 blade 18p. it's working great.

The holeshot is definetely stronger, and pulling wakeboarders, and skiers at a constant speed is even easier now