Prop advice needed

[Winnie]

I got my new Alumacraft Dominator 175 Sport with an E-tec 130hp motor late this summer. I still have an aluminum 14.75" x 17 prop on the motor (that's what the dealer put on it.) So far am disappointed with the performance only getting as high as 39.8 mph GPS. I thought the 130 would move it faster than that with even with the aluminum prop. I was hoping I'd get at least 45 mph with this set up. The engine is mounted on the 2nd hole from the top out of four holes.

My deal for the boat included a stainless prop which came in several weeks later and I have not yet put it on. It is a SS Evinrude Viper V6 14.75" x 17 prop still in the box, again this is what the dealer indicated would be the right prop to put on this boat/motor. Is this prop likely to give me that big a jump in performance, or does anyone recommend a different sized prop or something different with the set up?

[Nimstug]

Winnie,

I can't answer your question but the person who will, will need to know what the maximum rpms are for your motor and what rpms you are running.

Nimstug

[Bandit]

RPM's Please

[ffishman]

I don't know either, but it sounds like you are close to being maxed out now.

[Winnie]

I don't know either, but it sounds like you are close to being maxed out now.

I'll have to get the RPM info, but I can't believe I'm maxed out. Evinrude has a performance report with a 115 HO and the very same boat and it maxes out at 43.9 MPH with a 14.75"x18 SS prop.

http://www.evinrude.com/NR/rdonlyres/4830367E-A72E-45C6-AE7F-EDA461E267DF/0/PE652.pdf

[Bandit]

I'll have to get the RPM info, but I can't believe I'm maxed out. Evinrude has a performance report with a 115 HO and the very same boat and it maxes out at 43.9 MPH with a 14.75"x18 SS prop.

http://www.evinrude.com/NR/rdonlyres/4830367E-A72E-45C6-AE7F-EDA461E267DF/0/PE652.pdf

After looking over the Evinrude test results I would start with the same prop? That prop with 130 e-tec should run around 5800 RPM & with the increase weight compare to the test report you should get 44 MPH??

[Senderofan]

Winnie:

Before I purchased my SS props for my etec I called Evinrude...the tech there said the Viper performs nearly the same as their aluminum as far as WOT rpm's go. Comparing my aluminum 19" brp to the 19" Viper...I lost only 50 rpm's going to SS. As far as top speed....I want to say the SS was maybe 1 mph faster at the top end. This might be a function of better bite...or blade design.

Good Luck...The Viper is a nice prop...For my 175..I've switched to a Merc. Tempest Plus which works even better on my rig...thanks to Propmann!!

Wayne

[darin]

I cannot comment on which prop is right for your set up. However, once you find the right prop (be it from testing or advice or both) take it to a guy who knows what he's doing and have it worked. I had my 24P trophy worked. Before I had it worked, it was a touch slower than my hi five that had been professionaly worked. After having the 24P worked, I got another 4.5 MPH... no lie. Unbelievable in terms of staying hooked up, and the top end is much faster... my r's stayed about the same. Good luck. If you need a good prop guy in WI, shoot me a private message.

[Runaway]

Tthe sweet spot for your ETEC is right around 5600 rpms with your normal load. Check to see if your X-axis is set right. In most cases motor likes to be 3rd hole from top. Then start playing with props, I had an Alumacraft Tournament Pro 170 last year that I repowered to a 115 ETEC and ran both the Viper and aluminum 17Ps. Both had the same top end of 44 - 45 mph depending on the day and was right at 5650. The Viper made the boat jump instead of just getting up on plane like the aluminum prop did.

[Winnie]

Everyone, thanks for the great advice. Please keep it coming. I'm going to try to get her out this week to get a fix on the RPMs.

[Winnie]

OK, finally got the boat on the water today. RPMs at WOT was 5750 in relatively calm water, but could only hit 39 MPH. I've got to think I should be hitting close to 45 MPH with the right prop.

[OOC]

The 18" prop on the test boat was a Raker. I run one on my Tuffy Osprey 1760 with a Johnson115hp.The lift is incredible! It really dries up the hull.A Raker will not cavitate.This comes at the expense of a great holeshot. Finding one to test may be difficult. I have three Rakers, two of which have been customized by DAH in Burlington,Wi. They are 13-3/8x18 with 13 spline.Does your Etec have a larger gear case then the older V-4s?

[Winnie]

Gear ratio is 2.25:1

[Winnie]

Gear ratio is 2.25:1

Bump.

[yarcraft91]

He probably has a reason, but why is your dealer recommending props designed for Evinrude V6 motors for your V4? Can you get an aluminum V4 13 1/4x19 prop to try? (Style: 763464) The V4 prop will be a full 1.5" smaller diameter than the V6 prop, so you can probably turn a higher pitch without losing rpm and that might just increase your speed.

[propmann]

OK, finally got the boat on the water today. RPMs at WOT was 5750 in relatively calm water, but could only hit 39 MPH. I've got to think I should be hitting close to 45 MPH with the right prop.

As you said your motor is mounted 2nd hole. Most etecs run best at the 3rd hole. so the cavitation plate is about a inch off the bottom of your boat. If you go with a 14.25 x 17 pitch Powertech RAS ss you'll run about the same rpms. That prop has lots of cupping and rake so it gives you excellent holding and alot better bowlift. That will give you more speed just getting more of the boat out of the water. If you can move your motor up you'll be able to run at least a 18 pitch or even a 19 pitch that will really help with the speed. When you have the right setup you should be able to see 43 to 46 mph with that motor. The best testing is to find a powertech dealer in your area that will let you try out that prop. You can find dealers by going to www.ptprop.com or send me a PM and we can help you find some to try.

[Unlogged Eric Olson]

I will ditto the comment on the lower motor mounting position option but save the effort right now and try the SS prop first, properly load the boat with what you'd normally want in the boat.

Fill the tank livewell etc, etc. Write down rpm and speed at cruise, WOT and holeshot time 0-20mph. once thats done, then play with the trim to get a solid feel of the boat and motor.

Really watch the amount of trim you can get from the engine before blowing out or gaining rpm w/o speed gain.
If you have a heavier bow loaded boat this may prevent much trimming and be w slightly wetter ride. If thats the case then lower the motor one hole and redo the test, full fuel etc, etc

Keeping loads and test conditions the same, and doing small adjustments one at a time will make the time a rewarding and educatiuonal one... guaranteed!!!

In the application you have I don't feel you'd see much benefit from a "worked prop" so I'd say save the buck and buy some cool electronics, or crankbaits!! Bigger horsepower from 150hp on up and a more performance oriented hull absolutely!

Have fun
Tight Lines
Eric

[Winnie]

I finally ran the SS prop this weekend. I could tell the boat was a little more responsive to the throttle, but only got about 0.5 mph more top end ,albeit with fairly choppy seas, also RPM was up to 5800. not sure to what this can be attributed as most told me the SS would likely drop my rpm by 100 or so. Could be the motor's own break in period is allowing it to run a little faster? Think I'll have my dealer (Cabelas) raise the motor a notch and switch to an 18 pitch prop. Or should it be a 19? Please advise.

[REW]

Winni,
With the aluminum and the stainless essentially identical props, I would have guessed that your performance would also have been pretty identical.

The engine rpms are about right for your rig.

You are trimming the motor as high as possible aren't you. i.e. trimming as high as possible but not porpoising and not having the prop blowing out?

Where is the spray line on your boat. i.e. how much of the boat is in the water, when you are running wide open.

To get the very best performance out of your boat, you need to only have about 1/4 of the boats hull in the water when you are running wide open. The rest of the boat should only be seeing air. If your bow is down and you are plowing water, you will be running much slower than you should be running.

First insure that you trim up, up and up, until you can't trim up any more and see what happens to the boats speed and engine rpm.
Keep an eye on the tach and as long as the rpms continue to gradually rise, you are doing all right. If with only a touch of the trim up switch, you suddenly get a big jump in engine rpms, your prop has broken loose and you need to trim back down a bit. Keep jockying the trim tab up and down until the boat is just balanced on running as clean as possible without porposiing or prop blow out or ventilation.

REW

[Winnie]

REW,
That's what I've been doing. Granted the water was a bit choppy with holiday boat traffic, but I trimmed up slowly until I got only RPM and no speed increase. At this point I also started to get porposing until I trimmed down a bit to stabilize the ride. At that point I was getting 5800 rpm and only 40 mph. Spray line was somewhere behind me, but I didn't mark it exactly.

[nickyneb]

Winnie,

I have an 08' Alumacraft Dominator 175 sport powered with Merc 115 fourstroke. I know your pain well. I couldn't seem to find that sweet spot esp with top end till this year. I am at altitude (Denver) so my set-up is a bit different. But I will fill you in on what my own work on the water has given me.

I started with a s/s 16p vengance prop from merc and I couldn't make the rpm's I wanted. I switched to a s/s 14p silverado (merc's other s/s brand) and voila rpms were almost right with a two guys full fuel and gear. Speed was almost a constant at 36.8-38 mph gps. But had annoying porpoising at top end.

Still not quite happy with my top-end I raised the motor two holes, I was on 2nd hole ( I can raise it one more if I want) and boy that did the trick. I gained top end/ hole shot and it stopped the annoying porpoising along with a few more rpms. Top end gps went to 38.5-40 mph.

Over the holiday weekend I was back in NE (elevation approx 3200ft) and just for kicks I threw 16p vengance back on to see if I could get more speed. Nada. I lost approx 3mph/hole-shot and rpm. Back to the 14p now. FWIW I had traded messages with propmans company (super helpful and honest and they said my set-up was as good as I could expect.

I really appreciated the honest and straightforward answer from their company and if I need another prop in the future they WILL get my business.

I hope this helps I would definitely look into raising my motor if I were you. Good luck.

[Winnie]

Thanks, nicky. I talked to my dealer's shop this morning asking about the set up and mentioned the possibility of raising the motor. the tech basically told me my performance was good enough and that if I had the capability of raising the motor myself then go ahead. He didn't seem at all interested in their doing it at all. I am very disappointed in their apathetic reaction to my quesitons and inquiries about fine tuning my setup. The guy even acted like ordering an 18" prop was going to be a pain.

[phowler]

Raising and / or lowering your E-Tec is fairly easy with a block of wood & your trailer jack. The details have been discussed at length in the past and a search should give you all the info. you need.

It's nice isn't it when your dealer doesn't seem to care after the sale has been made.

Of the 1/2 dozen or so marine dealers I have delt with in my life exactly 2 of them would I ever do buisness with again.

[Winnie]

I'm curious what people think of putting a 4-blade Mercury Trophey Plus in a 17" pitch would do for this boat/motor combo. Would raising the motor to the third hole still help with this prop? How much are RPMs likely to decrease with this prop over a 3-blade 17" prop?

[Kris_2020]

I'm curious what people think of putting a 4-blade Mercury Trophey Plus in a 17" pitch would do for this boat/motor combo. Would raising the motor to the third hole still help with this prop? How much are RPMs likely to decrease with this prop over a 3-blade 17" prop?

I went with the Trophy Plus 17 pitch on my Lund Explorer 1725 Sport and a Merc. 115 EFI. I got 6100 rpm at 40 mph. My 3 blade aluminum 19 pitch got me about 5800 rpm at about 43 mph. The 4 blade was way better in hole shot and especially handling.
I am now waiting to receive the Trophy Plus in a 19 pitch and then I`ll give that a go see how it compares.

[nickyneb]

Winnie,

I know I mentioned before about raising your motor. Do a search on this board and there is a link somewhere to verado owners group which shows exactly how your motor should be running.

[REW]

Purchase or buy an aluminum 19 pitch prop for your rig.
Take it out by yourself, trim the motor as high as possible without blowing out or porpoising and check your engine rpm.
See if you can still get about 5600 rpm.
If you can get the motor up to 5600 rpm or so, you should be running over 40 mph.
If the prop bogs your motor down below the 5600 rpm mark, your speed will be less than what you have right now and you will have to go back to the lower pitch prop.

Good luck
REW