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WakeWorld Discussion Board » >> Boats, Accessories & Tow Vehicles Archive » Archive through February 10, 2003 » Improving I/O performance « Previous Next »
By Adam Cloutier (rishermrp) on Monday, January 20, 2003 - 1:01 pm:    Edit Post Delete Post
I have a 18'6'' I/O and I am looking for a way to make it easier to stay on plane and produce a larger wake. The dealer said it would help to put as much weight up front and as possible and he suggested testing a 5 blade prop which he says helps with larger boats but has never tried it on a 18ft boat does anyone have any opinions or suggestions
By james mccallum (jmccallum) on Monday, January 20, 2003 - 1:44 pm:    Edit Post Delete Post
yes and yes.
By Ken E (airfreak) on Monday, January 20, 2003 - 1:53 pm:    Edit Post Delete Post
We started with one of the fins you put on the out drive and they will help you stay on plane. If you go with weight the fin may not be needed. Would suggest atleast a 4 blade if not the 5. The only 5 I know of is stainless, and I wasn't going with SS due to $ and for fear of hitting a log and tearing of the out drive. If you have clean lakes then go with SS.
By Darren Yearsley (ralph) on Monday, January 20, 2003 - 2:36 pm:    Edit Post Delete Post
What size motor is it and how much weight are you going to run
By Adam Cloutier (rishermrp) on Monday, January 20, 2003 - 3:13 pm:    Edit Post Delete Post
4.3lt 190 hp not sure how much weight yet i think the power might be an issue since it is a really heavy boat for its size and when there was a full load of people in the boat it took forever to get on plane at full throttle
By Darren Yearsley (ralph) on Monday, January 20, 2003 - 3:17 pm:    Edit Post Delete Post
I would run a 16inch pitch 15 or 16 inch diam prop, 4 blade aluminum. We push 2k with a 135hp 3L using a 15 inch pitch ok. Get at least 1/2 of your weight forward of the windscreen.
By Adam Cloutier (rishermrp) on Monday, January 20, 2003 - 7:58 pm:    Edit Post Delete Post
how much do you think i should weight it i know the boat itself weighs 3000lbs so whats a good starting point
By Darren Yearsley (ralph) on Monday, January 20, 2003 - 9:19 pm:    Edit Post Delete Post
A good starting point would be a 500 pound sac in the walkway (or ski locker if it fits) and peeps in the back, you will have to trim to get the wake to clean up.
By Bobby Mucic (bobbymucic) on Tuesday, January 21, 2003 - 8:01 am:    Edit Post Delete Post
If you have a merc 4.3 and alpha one drive, you will want a pitch between 19-20.
Ralph's advice is for a really loaded down boat, with a smaller motor (and perhaps a different drive ratio). I'm guessing that if you put a 16 pitch, your top speed will be about 35 mph before you over-rev

I have a 19ft i/o with the above engine and have used many different set-ups.
try a 20 pitch four-blade alum prop..about $150
and maybe something like a doel-fin ~50 bucks

add 250-500 lbs of ballast in the bow and you should be set.

Holding a consistent speed may be bear. You can install perfect pass for $800-1100. If you really plan on boarding a lot, and are keeping the boat for another season, get perfect pass

By Phimple (phimple) on Tuesday, January 21, 2003 - 12:40 pm:    Edit Post Delete Post
Can a perfect pass be fitted to any I/O? If so how hard is it to retro fit one?
By E.J. (deuce) on Tuesday, January 21, 2003 - 12:52 pm:    Edit Post Delete Post
Contact Perfect Pass and they will be able to tell you if you can install on your current motor/outdrive. They are great.... or


By Murphy (bigfaceplanter) on Tuesday, January 21, 2003 - 1:50 pm:    Edit Post Delete Post
If you have a mercruiser the linkage will install
the same as a real ski boat. If you have
a OMC because of the backward linkage they use
you will be doing some "custom install work".

Perfect Pass is the I/O's #1 improvement mod.
A bit pricey but well worth it. You can now let
your wife/anyone else without any throttle problems!!!

By charlie alexander (charlie) on Tuesday, January 21, 2003 - 4:24 pm:    Edit Post Delete Post
I have a 19.5 foot reinell, with the 4.3l volvo penta engine and outdrive. With the stock 21 pitch aluminum prop I had trouble staying on plane at low speed so I added the fin and it planed sooner for sure, about 18-20mph. Wakeboarding was a mess, though, because the fin killed the wake by lifting the rear of the boat. At the suggestion of my dealer, I changed the prop from the original three blade 21 pitch aluminum to the 5 blade stainless steel prop (called the high five) and took the stupid fin off. The only real visible difference was that the stainless had 5 blades, is way heavier and was one inch smaller in diameter. Advantages(for me): faster rev times, faster hole shot, silky smooth acceleration, lower planing speed. And, of course, the elimination of the fin, which stuck out beyond my swim platform and was a scratch hazzard to your legs. I still have the same RPM per MPH ratio I started with when I had the 3 blade aluminum, but speed is easier to hold now. Disadvantages: loss of about 2 mph of my top end speed (now max is 48), and I had to buy a prop lock so it wouldn't get stolen. While this setup works for me, I can't say it would work in all cases, you have to check with your dealer I guess, or try different things. I just wanted to get rid of the stupid fin for wakeboarding, yet still be able to plane out of the water quickly when I wanted to, and this combination is good for me. good luck.
By Bob (bob) on Tuesday, January 21, 2003 - 6:03 pm:    Edit Post Delete Post
I second what Murphy says about the PP and I/O's!
Charlie i posted about 2 or so years ago that the doel fin (what i had and removed)did the same thing your saying, FLATTEN OUT YOUR WAKE, just dont do it.Add weight to the front, put a smaller pitch prop on with more then 3 blades.
Charlie: Is your high 5 a 21" pitch, cause im running a 19 on a 20' -3400 lb boat that i sack down and am thinking of going smaller still, towards what Darren is saying but not quite that small
Try this link for the merc prop selector, be sure to add the weight of any ballast you may be running.

By Riverfreak (riverfreak) on Wednesday, January 22, 2003 - 12:49 pm:    Edit Post Delete Post
I was wondering when someone was going to shoot down the doelfin idea, those things destroy wakes or at least I've been hearing that for years, I have the hi-5, pricey and cost me $200 just to get fixed last year, but makes a world of difference, My boat is an 18.6 with the 4.3, I put 500 in the bow + peeps and the wake is sweet....I've tried different props just to see, and the prop really makes the difference, you could probably just go with a 4 blade low pitch like 17 or 19, I wouldn't go above 19, anything more is gonna be more top end speed, not hole shot and plane at lower speeds....
By charlie alexander (charlie) on Wednesday, January 22, 2003 - 9:32 pm:    Edit Post Delete Post
Bob, my high five is a 21 pitch, same as the stock aluminum 3 blade. I was lucky in that I didn't have to change pitch at all, which helps a bit on the gas useage.
By Murphy (bigfaceplanter) on Thursday, January 23, 2003 - 8:27 am:    Edit Post Delete Post
I went from a SS 19 pitch 3 blade to a SS 4 blade 17 pitch. It pulls much better and I didn't really lose any noticeable top speed.....but I rarely run it above 4000 rpms....well maybe the
last run of the day when I've had a few beers!

I think the fear of blowing your motor is overrated unless your are a barefooter or topend
speed junkie. Wakeboarding power requirements aren't anything near redline.

(Message edited by bigfaceplanter on January 23, 2003)

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