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Author Topic:   18 Outrage/140 Johnson prop size...
HJB posted 05-23-2003 08:51 PM ET (US)   Profile for HJB   Send Email to HJB  
I own a 1989, 18 Outrage with an 89 Johnson 140 ob. I need a correct prop size, to maintain plane at "lower" speed(s). I currently have to cruise around 3600 rpms to stay up on plane. Anyone own this boat setup, and can assist on my planing dilema?

*I've posted this question before-but, some wanted to know my current prop size--15x17.

Sal DiMercurio posted 05-23-2003 11:32 PM ET (US)     Profile for Sal DiMercurio  Send Email to Sal DiMercurio     
Your twisting a "V" 6 - 150 hp & up prop at 15 diameter.
Are you saying you fall off plane below 3,600 rpms ?
That boat should be cruising about 28 - 30 mph at 3,600 rpms.
Are you certain your tach is reading right ?
That engine should be able to twist a 13-1/4 x 19 & blow you out of the hole, keep you on plane at 3,000 rpms & push that boat about 48 - 50 mph.
Are you loaded down heavy at the stern ?, if so, move some weight forward.
You really shouldn't need a dole fin or plates keep you on plane at 3,6000 let alone 3,600.
Give us some speeds at certain rpms, such as 3,000 through wot.
HJB posted 05-24-2003 12:34 AM ET (US)     Profile for HJB  Send Email to HJB     
Thanks, for the input. I have no electronics (except VHF)on this particuliar boat-the boat is rarely used only about 50 hours since new/89... I will make use of some freinds and see if I can get a few RPM/speed readings.
Yeah, I meant anything under 3600 rpms seems to make the Outrage "plow". Some tell me only to purchase a RAKER prop-something about this is the best to use on OMC outboards-any truth? I'll also check out the motor/bolt/hole mounting set-up, been reading other subit's-lot's abotu motor mounting.
Sal DiMercurio posted 05-24-2003 06:23 PM ET (US)     Profile for Sal DiMercurio  Send Email to Sal DiMercurio     
I'm running a 200 hp [ really 222 hp ] on my 20' Outrage & the best performance i'v had is with a Stiletto prop 14.25 x 21.
Boat rides "much" higher on the water & no problem staying on plane at 3,000 rpms, in fact she runs about 27 mph at 3,000 rpms.
A Stiletto is a lifting prop, see if you can borrow one & try it, but you certainly don't need a 15 diameter on that boat, should run a 13.25 to a 13.3/4 diameter & off the top of my head, i'd say a 13.25 x 19.
HJB posted 05-24-2003 09:02 PM ET (US)     Profile for HJB  Send Email to HJB     
Sal, I took the boat out today-WOT she's screaming at 6200rpm with the 15x17. Still try the size you spoke of in previous reply(s)?
Sal DiMercurio posted 05-24-2003 10:03 PM ET (US)     Profile for Sal DiMercurio  Send Email to Sal DiMercurio     
HJB, that way to many rpms for that engine, don't let her run that high.
Ok, a 14.25 x 19 Stiletto should bring you down to about 5,700 as the Stiletto should bite better & erase an extra 100 rpms, plus the 200 per inch of pitch = 400 ....500 total.
If it were me, i'd allow 5,700 rpms but back off about 5,500, if she still wants to rev 57 or 5800, bring the prop in to a good prop shop & have them put enough cup in it to drop down about 2 - 300 rpms.
HJB posted 05-24-2003 11:14 PM ET (US)     Profile for HJB  Send Email to HJB     
Cool, thanks for your input.
You know any thing about hydraulic steering? I have a slight leak at one end of the long black cylinder that slides back and forth on the steering rod.
Sal DiMercurio posted 05-25-2003 12:35 AM ET (US)     Profile for Sal DiMercurio  Send Email to Sal DiMercurio     
Not without seeing it.

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