Re-Pitch or Re-Prop?

[imported_74baja]

Hi all,
I have a 1974 16' Baja speed boat with a 1999 Johnson 115. Currently my wheel is an 18 pitch Raker. On my last run this year, I cruised along for a while, but ever since getting the new motor (old one was a '74 115 shaft rated hp vs. prop rated with the new one) I couldn't help thinking that I feel like I'm going to slow for higher rpms, however, ever since I did the transom replacement, I haven't gotten around to hooking up the speedometer. So, on the way back, I hit it and saw the tach hit just over 6k with some throttle still left and I backed off. So, since the recommended is 5-5.5 k I figure I should prop up a bit. Also, I was thinking of raising the engine up a hole, since the cav plate is just about even if not slightly below the keel. So, I guess I'm wondering if it makes sense to bring the prop to a prop shop and see if they can re-pitch it, or get a new prop. My current prop is not in excellent shape, it has one 1/4 inch ding and a few smaller ones (previous owner). Can a prop shop repitch the prop my guess of about 1-2" that I will need, or does it make sense to get a new prop? Also, I have not been able to find any sites that sell raker props, are there any?
Thanks, sorry for the long post,
Jack

 

[walleyehed]

Re: Re-Pitch or Re-Prop?

You can find Rakers on ebay most of the time...as for a new one, it'll be BRP dealers only and will be the RakerII series.
Your '99 115 should be a 60 deg looper and 6k is your target RPM for that engine....anything under about 5800 is starting to close-in on lugging. 5500 on todays fuel won't do it any good what-so-ever.
You need to make sure the tach is accurate and open it up to WOT and see what it will turn. It won't go over about 6400-6500 anyway..the reeds will start to float..not a problem and it won't hurt anything to see where it maxes out.
A newer 18P raker may be in better shape with less wear and provide the extra bite to bring it down rpm-wise, just a hair. If it's pushing the 6400 mark, I go to a 20P raker and work the set-up as needed to get it at 6000 with a normal load. If it falls inbetween that, you may want to look at a turbo.
Which side of the engine is your tilt switch on?

 

[imported_74baja]

Re: Re-Pitch or Re-Prop?

Thanks Walleye,
Yes, my engine is a 60 degree looper. The trim switch is on the port side of the engine when looking from behind the boat. I didn't know I could rev that high, wow. How much do new rakers usually cost?
Thanks,
Jack

 

[walleyehed]

Re: Re-Pitch or Re-Prop?

I haven't priced a new one lately and I'm more of a Turbo fan, but I'd guess them around 400.00.

 

[Ez-J]

Re: Re-Pitch or Re-Prop?

Hey baja,
I have a '94 115 evinrude on a 14'6" boat . It had a 17" solas on it for skiing when I bought it so I thought I'd try a 21" Hustler when i went to buy a larger prop seeing as they're dirt cheap.It now revs to 5500 w.o.t. ( 6500 with the 17" ) I can't believe how well it performs, especially for the price. It has great hole-shot and can be trimmed waaaaaaaaaaaay out without cavitation. It also hangs on well in tight turns. I had a 28" cleaver and a 26" chopper on my last boat so I know what a good prop feels like. Hope this helps some.

 

[walleyehed]

Re: Re-Pitch or Re-Prop?

A '94 Looper at 5500 isn't going to be around long...and the Hustler has shown itself to have a higher than normal slip ratio in every case I have tested them.
On another note...if you can trim "Waaaaay out" your engine is mounted too low on the transom.

 

[achris]

Re: Re-Pitch or Re-Prop?

A '94 Looper at 5500 isn't going to be around long...and the Hustler has shown itself to have a higher than normal slip ratio in every case I have tested them.
On another note...if you can trim "Waaaaay out" your engine is mounted too low on the transom.

I thought a '94 115 was one of the old crossflows. The V4 loopers were 120 and 140....

Chris.............

 

[walleyehed]

Re: Re-Pitch or Re-Prop?

A '94 could be either...that was the first year of the 60 deg looper 115 "eagle series". 5500 would still be the minumum for a crossflow.

"The V4 loopers were 120 and 140...."
You forgot the 115 and 130...
the 120 and 140 were 90 deg loopers of larger displacement in '85 and 86...then they went back to the original displacement.

No, he doesn't mention which it is, I just added "if it's a looper"...

 

[Ez-J]

Re: Re-Pitch or Re-Prop?

I don't sell props so what you buy doesn't affect me. Just sharing my recent prop-buying/testing experience with you. I don't know how hustlers behave on other rigs but according to the prop calculator here http://www.rbbi.com/folders/prop/propcalc.htm . and my gps , I'm getting between 8 and 10 percent slip at different speeds. ( 50 mph at 5500 revs full throttle ) As for the height of my motor , the cavitation plate is fairly even with the bottom of the hull. By trim it waaaaaay out , I meant compared to the omc , piranha and solas props I had tried previously. As for the motor not lasting long at 5500 , I'm not quite sure what you mean. It had new pistons and rings 60 hours ago and the recommended w.o.t both in my owners manual and here. http://www.piranha.com/motor_specs.php?id=4368 , is 4500 - 5500. It's a 90 degree " looper ". All I know is I'm glad I didn't spend 3 times as much on a SS prop for the extra 1 mph gain that I could just as easily obtain by cutting the wife off cold rock ice cream for a couple of weeks.

 

[walleyehed]

Re: Re-Pitch or Re-Prop?

Not to steal a thread here, but maybe some others can extract some info too...
I show 11.6% slip with the numbers you give...at 8% slip we'd be around 52GPS so we aren't that far off.
As for the RPM issue, you must understand the date the engine was built and the quality of fuel we had 14 years ago compared to todays fuel.
We've found that on engines of that age, if we run the RPM up in the 5800 range, these is much less coking, carbon build-up and much better fuel economy....If the proper maintenance is followed, there is NO reason (except too low of max RPM) that a '94 should require pistons..."IF" proper maintenance was followed.
There are engine manufacturers here, racing techs, prop specialist, etc, that can verify what I'm telling you..I learned this from one of the Race techs here that has Run some classes that require stock engines. Over the years, I have ran all of the crossflows at or above 5800 (6000 for loopers-propped for) and these engines have required very little attention in the way of any carbon build-up, coking, etc...but I work on many that are propped to run 4800-5500 max and all have sticky, gummy pistons, and compression on some of these have indicated sticking rings. I've saved a few with a major decarb operation and talking the owner into maximizing the set-up to gain RPM or in some cases, just dropped 1 step in pitch, although this is not the recommended first step-working the existing set-up IS the first step.

Your experience of only gaining 1 mph for an SS prop is typical of "Just bolting one on"...the technology is of a greater standard and the rig must be adjusted to utilize the technology of that prop.
With a couple of hours work lifting the engine (you're too low even for the Hustler with the AV plate level with boat bottom) you can see gains of possibly even 5mph by decreasing gearcase drag and reducing the amount of trim required to keep the bow up, of which a high quality SS performance prop with bow-lifting design will do with the engine at Neutral trim.

 

[Ez-J]

Re: Re-Pitch or Re-Prop?

The previous owner replaced the pistons. He was running a 17" solas on it so I don't think it was suffering from under-revving. Anyway , my point was originally , that a Hustler prop is dirt cheap brand new and they perform exceptionally and are already cupped. There's now way I could justify the expense of a SS prop unless I was racing. Also, if my motor's too low on the transom , explain the 52 mph gps I get from a 115.

 

[walleyehed]

Re: Re-Pitch or Re-Prop?

The previous owner replaced the pistons. He was running a 17" solas on it so I don't think it was suffering from under-revving. Anyway , my point was originally , that a Hustler prop is dirt cheap brand new and they perform exceptionally and are already cupped. There's now way I could justify the expense of a SS prop unless I was racing. Also, if my motor's too low on the transom , explain the 52 mph gps I get from a 115.

I'll explain that....
It's why you're not getting 56-57mph out of it....that's why.
Your fuel savings from a properly set-up rig with an SS prop would pay for the prop in one season if you use it much.
Correct me if I'm wrong, but you must be using a 21P for the numbers to work out, and that's using 10% slip...the Hustler won't pull down to 8%.