Propeller Selection tips?

[SloppySeconds]

Hey there folks,
I was curious if you guys had any recommendations for selecting the right prop for your boat/motor combos. I'm looking for a stainless prop for my 1997 Ranger R70 (17.5') with a '97 Merc 115. I used the Mercury Prop Selector website, but it keeps kicking out 17 pitch props - which is a lot different than what the folks at Ranger had recommended - a 13.5x22 LaserII. Even the local Ranger dealer had a 23 pitch prop on a similar boat... so now I'm a bit confused. I'd hate to drop that kind of cash and get the wrong prop. Any suggestions?

Thanks!

[Fishin' Dave]

I would call Boatmasters in Dublin. They have loaner props so you can try before you buy.

The prop selection really depends on the hull design of the boat. Rangers have been run successfully with 3 different props. I had a friend that ran a 23p tempest (3 blade) on his 363 with a 150 opti because he liked the bow lift it gave him. He also ran a 10" jack. Most Ranger guys I know run a Trophy (4 blade) prop because Rangers are heavy and the 4 blade carries the weight better. A third option is the Steve Sapp option. On his old Ranger he ran a high 5 (5 blade). He liked it because it was easy to get on pad, turn, and stay on plane at a slower speed. He did not mind the top end sacrifice for his style fishing.

Good luck!

[ripbait]

Call Gary Peeler At TRU-PITCH He is in Sacramento 916-332-4229

[MrSkeeter]

Post your question here: http://bbcboards.zeroforum.com/zeroforum?id=11 and here: http://www.wmi.org/multi_boards/props/index.html

Rich Boger, the moderator in the second forum, is one of the best known prop guys in the country.

But before you do, you need to know the following with your current setup:

1) Motor height (measure the shaft to the bottom of your pad)
2) Max RPM at WOT
3) Water pressure at WOT
4) Amount of setback your motor is relative to your transum (jack plate installed? If no, get one or you will have a hard time optimizing your setup)
5) Max speed (GPS reading is better)

Generally speaking, your Laser have a lot of slippage ... thus not transfering the energy your motor makes to the water inefficiently. The Merc Tempest series (3-blade) and Tropy series 4-blade) of props will probably do a better job. But depending on your hull (which I'm not familar with), some run better with the Tempest and others better w/ the Trophy ...

Also, the the 4-blade props GENERALLY handle better as there's more metal in the water at any given time. Sometimes (maybe not always) the drawback is a little speed loss.

That said, I suspect you're probably going to be looking at something like around a 19 pitch prop ... But it really would depend on your motor height setting and water pressure (a key figure that you MUST know when running at all time).

Only way to know is to go get a loaner and try it before buying it. People at Boatmasters II in Dublin and the Boat Dock in Fremont have loaner props. But better call ahead before driving over just to make sure they have the one you want first.

[Ken C.]

Chris had some good info in his reply, however I would direct you to work with Phils Props up in Redding. Super knowledgeable plus he's a SITE SPONSOR!!

Click Here: Phils Props

You are going to need the info Chris told you about before you will get any reasonable suggestions. I am told that Rangers like props that give a lot of bow lift.

[scsiman411]

boatmasters in dublin helped me out with prop selection just last week and they will do the same for you too. loaners in stock.

[SloppySeconds]

Thanks for all the tips! Much appreciated. I finally got the boat on the water. With a light load, the boat did 41mph at WOT at 4800rpm with a 21 pitch Ballistic stainless. I think I better drop it down to a 20 or 19 pitch prop.

SS

[twister]

Sloppy,

Somethngs fishy with your performance. Is this motor a four or a
two stroke? 4800 RPM sounds too low--did you trim the motor just
before the prop starts to ventalate? Top speed for that boat should be around 50 mph under the right conditions (slight chop, no head wind and a reasonable load). My shitty Astro with a two stroke 115hp Merc does 48 mph (speedo not GPS) with my hefty friend and I (165 lb + 250 lb + 50 lb of gear= 465 lb). A 19P is way too low. If that your preference then I have a SS 19p for sale.

Operating RPM for

Optimax: 5000-5750
Four Stroke: 5800-6400


Check out BBC (Bass Boat Central) for
simular setups.


http://www.bassboatcentral.com/ranger3.htm

[MrSkeeter]

I agree w/ Twister ... something is not right. Dropping one or two pitch will give you 2-400 RPM more, but ... might not be the the root of your problem.

Measure your motor height first. What's your water pressure? If you do not have a water pressure gauge, that would be the first thing to get. Water pressure is the life blood of your motor. You need to know what that is just about all the time. Too much, you're lugging the motor. Too low, you're starving the motor of cooling water. Both ends are not good ... Read your manual as to what the water pressure should be (15-20PSI?) at WOT. Make sure you maintain that with whatever changes you do.

I suspect your motor might be too low!! Generally, your motor should not be much lower than say 3" below the pad (shaft to pad). Put a straight edge on the bottom of your pad to your motor, something like a 2x4 or ?? then measure that relative to your shaft.

If your motor is much more than 3" below the pad. Then first thing to do is to raise the motor. If you have a jack plate, that's easy, just wrench it so the motor is raised. If you do not have a jack plate, get one ... or move your motor up one on your mounting hole (each hole is about an inch I believe). But my recommendation is if you don't have one, get one of these, maybe the 6" one is fine.

However, depending on your boat/motor, you might not want to be much below 2.5" either ... or you're water pressure might drop. But let the water pressure be your guide. Generally, start with about 3" below pad. Then make a few runs. Watch your water pressure. If you still have ~15-20 PSI or more at WOT, raise your motor a quarter inch ... and repeat. Once you see your water pressure begin to drop, then LOWER your motor a 1/4 inch and you're there!! At this point, you should have decent water pressure (depending on your motor recommendations, ~15-20PSI min) and should be rev'ing at near redline of your motor at WOT.

Having too much water pressure means you're lugging the motor too much (not a good thing; this usually also shows itself if you're not running sufficient RPM's ... way low rev's) ... too little means your motor is too high out of the water and you're not getting sufficient water cooling for the motor (also a very bad thing for the motor; this also shows itself if you're running too high RPM as well).

Now after this, you can now play w/ different pitch/props!!!

Like I said, generally, a pitch increase will DROP your RPM's by 2-300RPMs ... vise-versa is also true. Dropping your motor height will also drop your RPM's at WOT and increase your water pressure to some extent (the inverse is also true).

Good luck ... post what you decide on after trying out different props.

[SloppySeconds]

Wow, that's a lot of info. This is going to be a more serious investigation than I first thought. I'm pretty sure I had the motor trimmed correct, and I did several runs to tweak with the trim. I'm a bit new at running a bass boat, so there could be some operator error here.

The motor is a 2 stroke 115 with the 2.07 gear ratio. The manual says it should operate between 4800-5200 rpm at WOT, which I was surprised to see. I thought it would be around 5500. At this point, I don't have a water pressure guage, but I should probably get one installed. The jackplate may have to come after that.

I'll post the results after I play with the setup a bit more.

SS

[SloppySeconds]

So I put a straight edge to the pad and measured from that down to the center of the gear case... with the shaft parallel to the pad. It measured about 5.5 inches! The previous owner must not have noticed. So it would appear that the first order of business may be to either raise the motor two holes at 3/4" each to get at 3", or to just install a small jackplate and a water pressure guage - which I should do anyway. Decisions, decisions...

SS

[MrSkeeter]

So I put a straight edge to the pad and measured from that down to the center of the gear case... with the shaft parallel to the pad. It measured about 5.5 inches! The previous owner must not have noticed. So it would appear that the first order of business may be to either raise the motor two holes at 3/4" each to get at 3", or to just install a small jackplate and a water pressure guage - which I should do anyway. Decisions, decisions...

SS

If it was me, if I'm going to the trouble of taking the motor off the boat, I'm putting on a Jackplate before the motor goes back onto the boat.

5.5" is WAY LOW. With it so low, you will not be able to trim it out properly like you should. Also, if you don't have a water pressure gauge ... get one installed NOW ... or, check w/ a good Merc mechanic before moving the motor!! Like I said before, water pressure is the lifeblood of your motor. I'd rather have too much than not enough ... so error on the safe side.

My recommendation is to put in a water pressure guage AND install a small jackplate. Then you're going to be able to safely play with the motor height and prop selections.

[SloppySeconds]

As far as jackplates go, do you think I could get away with a small 4" or 5" manual jackplate for a couple hundred bucks? In was circumstances do folks use the hydraulic jackplates? Are those intended for larger engine/boat combinations with higher HP?

Thanks!
SS

[MrSkeeter]

For your boat, manual jackplate are fine. Get that Slidemaster (one I have on my boat) I had liked up. a 6" plate is what <$300. A hydraulic plate is about $1,000. The hydraulic plates allow one to adjust the motor height on the fly ... so for dead calm days, you'd move it up a bit to get a bit more speed, etc ... but from what I've seen, most folks set and forget!

With the plate, your boat will handle and maybe even ride a little better ... think of it adding 6" to your boat ... that's where the motor is after.

[CORAL 96]

Also check out www.bogerprops.com. Rich is known all over the country for his prop work & advice he gives on anothers site. He will give you the straight scoop on what's best for your application. He's had a few national publications recently write articles reguarding his work. Nice Guy!!!!!

[MrSkeeter]

Agreed. Rich Boger is a great guy who will help just about anyone with their setup problems. I've learned a lot from him .... he's the moderator in the WMI.org prop's forum. His email is Rich.Boger@bogerprops.com

[Ken C.]

5.5" doesn't sound quite right. I'm wondering if you placed your straight edge along the bottom of the hull itself or did you place it inside the "pocket" that is usually at the very tail end of the pad area on a bassboat hull? This is the area where your drain plug and livewell intakes are ususally located and it is typically a couple inches deep.

Here are the instructions from Bassboatcentral. Sorry I couldn't find the picture I was looking for but the idea here is that witha l-o-n-g carpenters level you have to have it along the hull and not inside the 'pocket':


"Take a long straight edge, (long carpenter's level or long steel ruler, etc.), and place it on the bottom of the pad in the center. Tilt your motor until the bullet of the gearcase is parallel with the straight edge.
Measure from the top of the straight edge to the center of the front of the "bullet" on your lower unit. This will be the center of the propshaft. This measurement would be the inches of the propshaft below or above the pad. (In the case of the faster hulls, such as Allisons, Bullets, Strokers, etc., this measurement could actually have the propshaft above the pad.)"


Check that out and see if you are truly at 5.5" below the pad before you do any adjusting...

[MrSkeeter]

Here's some good reads on basic boat setup, reference Ranger setups

Take note of the setup question with the guy w/the R70 and 115 Evinrude.

[SloppySeconds]

I read all the recommended reading you guys have provided. I did check again to make sure that I measured the distance from the pad to the shaft. I used a broom stick and ran it along the bottom of the hull, then measured down from the top of the stick to the middle of the gearcase. Definitely 5.5". I looked at the motor mounts, and they bolted the motor through the second holes from the top, placing it at about 3/4" from the top of the transom.

I'll keep collecting advice and will start by putting in a water pressure guage and making a few more test runs.

Thanks

[MrSkeeter]

Send an email to Rich Boger or Todd Morgan (BBC setup forum) and ask them what you should START your motor height at ...

In the mean time, I'd put in a water pressure gauge and a 4" jack plate. When installing the plate. Have them set the plate in the middle and the mount the shaft of the motor about 3" or whatever the experts (Rich or Todd) said .

Then run and take note of the water pressure ... compare it to your recommended settings at WOT ... note the RPM and see if the water pressure 'bounces' when you turn (right and left) ... if you still have more than the min water pressure recommended by your motor, then you can jack up the motor (via the new jack plate) by a 1/4" at a time as I explained above. Run the boat and note the water pressure, RPM at each run.

If you are getting plenty of water pressure but the RPM's are high, then it's time to up the pitch ... remember each pitch added DECREASES your RPMs by about 2-400 RPMs ...

Repeat till you get the RPMs and water pressure that is recommended by your motor!

Given what you've stated, 5.5" below pad, 4800RPM and slow speed ... it all makes sense. You're lugging the motor, it cannot spin a the optimum RPM's (because your motor is too low, you cannot trim out as needed to get the proper RPMs) ... your water pressure should be through the roof (if you had one to see) ... my guess is probably 20-25PSI ... by raising your motor, your RPMs should come up and if you raise it enough, your water pressure should drop to a more normal level (~15-20PSI?) ... you should see probably low 50's MPH and rev at ~5500RPM ...

My guess is that you're pretty close in terms of the 21pitch ballistic prop ... though I don't know much about that prop ... but if like some others stated earlier, if it is true that you need more bow lift, I think you might want to try a 21p, 22p or 23p tempest plus prop. Of the Merc props, the Tempest offers excellent performance and good bow lift ...

If you were to get a used prop, be careful ... make sure all the edges of the prop is sharp (especially the trailing edge) and no dings or work has been done to the prop ...

[Ken C.]

Check and watch the classifieds here and at BBC for a used jackplate. I see them for sale frequently. BBC has a classified section specifically for jackplates:

Jackplate Classifieds

5-1/2 inches below pad is likely way too low. As Chris recommended, take a look at the "Setups by Todd" forum on BBC, do a search on your hull and see what you can find. If you can't find your secific boat/motor combo then go ahead and post a request for info. Read alot of the other posts in there so you know what specifics they will need to know - that way you can post all the info for them to make a recommendation without alot of back and forth. Ask for jackplate recommendations as well. My recollection is the R series hulls usually take like a 6" plate. You can probably pick up a plate off the classy's for less than the price of a prop!

[SloppySeconds]

I spoke with the guys at Ranger and they referred my to their boat testing guy. Their boat tester made some pretty interesting comments about my setup and what these boats came with back in the day.

1997 R70 w/ Merc 115
Factory Prop: Laser II 22pitch
Motor mounted on second hole from the top
Factory test specs: 41mph loaded, 44mph with light load

With the Merc 125, the boat tested at 46 mph, with a Yamaha 130 it did 48.

He mentioned that a jackplate would have very little improvement in the peformance of this boat, gaining only 1-2mph. He also mentioned that a water pressure guage for this motor should read about 10-14psi while running on plane.

He was of the opinion that running at the top end of the RPM range was too risky, and preferred that the prop keep the motor in the middle to low end of the range. He also thought that at high RPM, fuel consumption was too high.

So I guess at this point, my best option would be to consider a LaserII prop and get that water gauge set up.

SS

[MrSkeeter]

Wow ... I'm surprised at a couple of those comments ...

1) water pressure at 10-14PSI???? ... I'd say, better check your motor's manual ... I'm not familiar w/ the 115 Opti, but the bigger motors require a min of 15-20. I'm running at 16-17 on my 175Merc.

2) The test speed expected at 41MPH loaded? Is that a WOT?? I'm surprise at how low that number is ... I would expect something in the ball park of 50Mph would be more appropriate!! But as I said, I'm not familiar w/ this boat.

The Laser prop has a lot of slippage ... not that efficient at pushing the boat relative to other props of that type, like the Tempest.

[twister]

I think his boat looks a little like this 1996 R70.


<img src="/shared/photos/photoother/resized/103_resized.jpg">

I think being a 97 boat you have a carb outboard not Optimax. I have a carb version
and it has no problems since rebuild last year due to a failed coil
the previous owner operated on (the piston basically melted
because there was no ignition). But since the rebuild I normally run
between the full RPM range you mentioned without any problems. I
can't tell the difference in Fuel efficiency if ran at 4800 vs 5100 rpm.
Heck I run from B&W around Franks (taylor, sandmound) and back
on 6 gal. Interesting motor because #3 and #4 cylinders are
designed to be leaned out at < 3000 rpm. At this point the mixture
is so lean that no ignition are in the cylinders. Oil however
continues to be supplied by auxillary plumbing. Well my opinion is
to go with Mr. Skeeters advice--


Move the motor up with or without jackplate. The jackplate just
makes it easier to raise. Power jackplates allow you to raise your motor when skimming in Franks. Your Ranger is a smaller version of my 488 VS--there's already built in setback. Typically setback
reducest he chance of vetallation around the prop, but your boat
already comes with enough. Raising the motor, like Mr. Skeeter
said, will reduce the drag your lower unit creates. Your boat
should pic up speed after you change the prop to 22p and raise
the motor. Just keep an eye on your water pressure.

I don't run a water gauge on my smaller boat with the 115 hp because it never came with one. Wish I had one when I ran across Franks on low tide because the temp gauge is too slow of a warning not to mention the siren. Those weeds in there can choke your plumbing in a matter of seconds. Heck, with all this cold weather I wouldn't be surprised if I can just air cool my motor by taking the cowling off. LOL

[SloppySeconds]

Nice post!
That picture is pretty much dead-on with the exception of the motor. I think that is all pretty good advice. I suspect I may see a difference when going to a different prop. In that respect, should I try a Tempest or a 4-blade Trophy? I'm not even sure they make a Tempest for 115hp engines? as I think they are meant for larger motors, given their bigger diameters. I suspect folks keep recommending the LazerII because they are better for smaller boats. Otherwise, the I think the Trophy would be a good choice. I'm just going to have to do some trial and error. After the prop and the water gauge, the jackplate might be another addition down the road.

After all, I've got some other mods to address first, like replacing my X-85 that just died, and putting in an onboard charger. Right now, those may be more important than squeezing out and extra 5mph!