Rookie looking for advice.

[kenmyfam]

I have a 17ft Doral outboard runabout with a 140hp Johnson VRO on the transom. 14 inch diameter prop with 17pitch, a little frayed around the edges. Runs 6,000 rpm and 42 mph. Pulls a skier out like they are not there. Just got a deal on a genuine 14 inch diameter with 19 inch pitch. I believe that it will be a little slower to plane but a faster top speed with lower RPM.
Any advice is extremely welcome.
I am an ex sailboater from several years ago and am rather green with the power boat end of things.
Thank You.

 

[Ron G]

Re: Rookie looking for advice.

The 19p should drop your rpms to around 5800,and by therory increas you mphs but could hurt your holeshot a little.one thing i have learned is every prop is different and reacts different to hulls.if its setup right you should be fine in my opion.lets see what the other guys think.

 

[Crownie2]

Re: Rookie looking for advice.

I agree with Ron. But as he notes, you just have to try it.

If you do much cruising around you might really like it because you will get the same speed (at cruise) at a lower, quieter RPM.

Let us know how you make out.

Bob

 

[Texasmark]

Re: Rookie looking for advice.

If everything else is stellar but the hole shot when pumping the ski up, you might consider porting this prop. Will do wonders for your hole (skiier hole). BTDT. A competent prop shop knows how and has the resources.

Mark

 

[kenmyfam]

Re: Rookie looking for advice.

I am not familiar with "porting the prop " ?? any explanation would be great. Anyway I have fitted the new prop and will be trying it out over the weekend and will let you all know.
Thanks for the opinions so far.
Paul.

 

[Ron G]

Re: Rookie looking for advice.

Its when you drill holes at the base of the blades it lets exhaust escape which makes the rpms turn more when takiing off and gratly improves holeshot with no effect on top end it truly works wonders alot of ss props are already vented.im trying to find a diagram that was posted on here but im having no luck.

 

[Ron G]

Re: Rookie looking for advice.

i finally found it but im to computer illetrate to put it here,go down to the 14 page and its under Post Subject: Re: holes prop Posted: 12:12pm 28 Jan '06
sorry i cant help with the pic:'(

 

[Ron G]

Re: Rookie looking for advice.

Finally got the wife to help me.this is from tommays thread

 

[kenmyfam]

Re: Rookie looking for advice.

Thanks for the great info. I have ported many a 2 stroke motorcycle engine but never even heard of porting a prop !!!
I am going to try the new prop out this afternoon both boat alone and then with a 200lb skier on the back. Will let you all know how it goes and if I need to consider porting it.
Thanks again,
Paul.

 

[kenmyfam]

Re: Rookie looking for advice.

Well,
Went for a trip this afternoon / evening running the new prop. Pulls out of the hole just fine with boat alone. My skier (son) had to work late so did not try that out yet and Lake St Clair was pretty choppy so a WOT test was near impossible with a nervous wife on board, however we cruised off to supper and back at around 25 to 30 mph at noticably lower RPM.
Balance of the report to follow tomorrow evening (weather conditions and my son being available permitting)

 

[walleyehed]

Re: Rookie looking for advice.

What year is your 140?
This will make a difference in the required top-end RPM.

 

[kenmyfam]

Re: Rookie looking for advice.

I believe its a 1985.
It is a V-4 VRO 140hp Johnson.

 

[kenmyfam]

Re: Rookie looking for advice.

Latest update.
Now runs 43 mph (verified by both speedometer and GPS) at 5200 RPM (WOT) also had the boat loaded with about 1000 pounds of people / equipment. Still have not tried it with a skier on the back as my son also had to work all day today and he is my guinea pig !!!
Seemed a little slower out of the hole today but cruises nice at 30 mph at 4,000 rpm.
So far so good but iwill not be fully convinced till we ski with it.

 

[walleyehed]

Re: Rookie looking for advice.

OK, now "I think" you have a v4 looper of early vintage, and the RPM needs to come up about 600 more with a normal load..."then" you will be set-up for pulling skiers and best efficiency over-all. Count the prop splines...should be either 13 or 15..If it's an 85 or 86, the 17P should be 15X17 not 14. At any case, your R's need to be no less than 5700-5800 with a normal load.
The 19 at 5200 is near lugging for WOT and will not provide much for hole-shot.
I could be wrong, but I believe your tach is reading 100-150RPM high based on slip ratio with the numbers and load you give.

 

[kenmyfam]

Re: Rookie looking for advice.

A 15" diameter will definitely not fit as the 14" only just makes it with a quarter inch to spare !!!
It is a 13 spline and I have been informed from someone at my marina that it "looks like an "88" vintage motor ???
Think I may have to go back to the 17 P

 

[Crownie2]

Re: Rookie looking for advice.

Get the thousand pounds of people and gear out of there! Unless that is your normal load.

I think what we are seeing here is that new props are designed better, generally with more blade area than an old "used" prop and will bring down the RPM's more than you would think the pitch change alone would indicate.

Bob

 

[kenmyfam]

Re: Rookie looking for advice.

Will be trying it out again tomorrow (weather permitting) with 400lb on board. I will report back how that goes. This is a great site and I very much appreciate all the help and friendly advice available from all of you.

 

[kenmyfam]

Re: Rookie looking for advice.

Well just got back from the best evening session I have had on Lake St Clair. Had myself and my 2 sons (600 lb) on board. Pulling 44 mph and 5,500 rpm. Hole shot good. Pulled my son (185 lb) out on skis no problem. Had a riot with the tube !!!! dont know if this is the best set up for me but it sure was fun !!!! I will probably get the prop ported over the next week or so or maybe do it myself if I can get enough info. I am an ex tool and die maker now engineer so have access to all the machinery I need to do the job. Boat runs great at 35 mph and 4,500 rpm. Handles great and feels comfortable.
Please let me know your thoughts and opinions before I proceed any further.
Thanks again for the great support offered here.
Paul.

 

[kenmyfam]

Re: Rookie looking for advice.

OK, now "I think" you have a v4 looper of early vintage, and the RPM needs to come up about 600 more with a normal load..."then" you will be set-up for pulling skiers and best efficiency over-all. Count the prop splines...should be either 13 or 15..If it's an 85 or 86, the 17P should be 15X17 not 14. At any case, your R's need to be no less than 5700-5800 with a normal load.
The 19 at 5200 is near lugging for WOT and will not provide much for hole-shot.
I could be wrong, but I believe your tach is reading 100-150RPM high based on slip ratio with the numbers and load you give.

So what is a V4 Looper ???? The V4 I understand but the "looper" I do not. Can someone explain please.

 

[walleyehed]

Re: Rookie looking for advice.

You don't have a loop charged induction, which the 85 and 86 had with a V6 gearcase.....yours is a crossflow induction with the std V4 lower unit, so the prop you list is actually the upgraded 17P. The Older 17's were 13-1/4...either will work fine.