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DanC

Mercury prop selector

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I want to order a stainless steel prop. I have a 2010 Tracker Pro Team

175 TXW with a 2011 75 HP Mercury Optimax. When I go to the the prop selector it gives me three different ones. Two are almost the same and have 3 blades. The other has four blades. The prop that came with it has four blades. What reason would I want four blades instead of three or vice versa? My goal is to make the boat as fast as possible. If I went with the three blade prop would I want the one that is slightly bigger and more pitch or the smaller one? I have attached a photo.  

IMG_1909.PNG

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I have been eyeballing the newest 4 blade prop myself and have been considering trying one out.  Current running a 3 bladed SS Tempest Plus - Though not at all unhappy with it - still fun to look.

Admittedly I'm no expert on prop selection, so here's some info on the subject from some humans who are better versed on the subject that I. 

 

"Three-blade props offer a nice compromise when it comes acceleration, efficiency, lift and speed. A four-blade propeller, on the other hand, can boost acceleration, efficiency or lift, but at the cost of a lower top speed.

 

Most outboards — 90 percent by some estimates — are equipped with three-blade propellers, and most offer strong performance. Yet can you expect better performance from a four-blade prop? The answer is yes — and no — according to experts from some of the major outboard brands.

Three-blade propellers are popular because they tend to offer a performance compromise, a pleasing (or at least satisfactory) blend of acceleration, fuel efficiency, lift and speed.

But if you want to improve acceleration, fuel efficiency or lift, a four-blade might help.  Just be aware that performance gains in one area can mean performance losses in another.  It’s all about what’s most ­important to you.

Also, before changing props, make sure there are no other factors adversely affecting performance, such as hull fouling, lack of adequate power, or improper weight distribution. Only after you are confident that the boat and power are well-tuned should you then move on to propping.

Define Your Goals

Decide which performance attributes you desire most. The captain of a flats boat, for example, might want to pop up on plane more quickly, and add lift for running in very shallow water. Often, a four-blade propeller is the ticket.  The additional blade area grips the water better, allowing for quicker acceleration.

The greater blade area also lifts the hull more while underway, which minimizes draft. However, the additional drag generated by an extra prop blade can also reduce top speed.  

While speed is important to some anglers, others seek fuel efficiency and the fishing range that comes with it.  This is where a four-blade prop can really help."

Read more here ~ http://www.sportfishingmag.com/propeller-choices-3-blade-or-4-blade-props-0#page-3

A-Jay

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A four-blade prop will improve your hole shot and get you on plane more quickly, provided your motor has enough torque to handle the increased "bite" of the prop over a three-blade prop. Many of the Mercury props have removable vent-hole plugs that allow motors to use props that would normally have a little too much bite for the motor. When you vent the prop, it lets exhaust gases escape at low rpm, which allows the prop to cavitate and spin more freely. At higher rpm, increased pressure keeps the exhaust gases from escaping through the holes.

 

Changing the prop on my 2017 Mercury 115 Pro XS four-stroke from a three-blade to a four-blade prop was a night and day experience. I use a Spitfire X7 four-blade prop that didn't compromise my top end speed, but now my boat gets on plane faster and with much more linear acceleration. With a coangler, full tourney load and full livewell, I can still run at over 45 miles per hour, which is the speed limit on Connecticut's larger lakes.

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Four blade will get you out of the hole quicker, but you are going to lose a little on top end.

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19 minutes ago, DanC said:

What kind of boat is it?

 

I have a 2017 Triton 179 TrX. Here's a photo from when I got it in January, but the boat now has dual consoles:

 

dqojkP.jpg

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I've put in my time and $$$ doing the prop tuning thing enough to know that I will go 4 blade every time, without hesitation.  If I was only worried about top speed then I'd consider 3 blade but if you work it right you can get a good 4 blade pretty darn close to your best 3 blade efforts and come out ahead all around.

 

If you're gonna fish, go 4.  If you're gonna fish competitively and every fraction on top is your obsession, go 3.  If you put in the time to dial both to best results and then compare, I'd bet you'll choose 4 in the end.

 

I currently run 2 different Trophy Plus (4 blades) on my rig...spring and fall colder temps 25p and 24p in the summer heat.  I want to try a 23p Hi-5 now just to see what I can get out of it.

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4 blade for big water rough conditions and pulling skiers/tubes. 3 blade for everything else 

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I just noticed that when I look up my motor which is an Optimax 75  and it says the rpm at full throttle is 5500–5750.  One Sunday I looked at mine tachometer at full throttle and it said 6000.  If I put in 6000 and my gauge is off a little, what would happen if I got the wrong prop?

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Watch your tac and keep it under 5800 rpm's when running long distances. 2 cyc OB Merc isn't going to be a problem at 6000 rpm's for a few minutes run time unless you have a very lean gas to oil ratio.

75 hp bass boat with livewell full, get the 4 blade SST prop.

Tom

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4 hours ago, DanC said:

I just noticed that when I look up my motor which is an Optimax 75  and it says the rpm at full throttle is 5500–5750.  One Sunday I looked at mine tachometer at full throttle and it said 6000.  If I put in 6000 and my gauge is off a little, what would happen if I got the wrong prop?

If you were to buy or borrow a Mercury VesselView Mobile, you could see the actual RPM as reported by the motor.

 

Since your RPM might be a little high at full throttle, your motor could probably handle a little bit more prop, such as a higher pitch three-blade or a four-blade. I agree with WRB; I'd get a four-blade prop. However, since you said that your goal is the highest possible top-end speed, a higher pitch three-blade prop would be your best bet.

 

I'm in central Connecticut. I know that it'd be a bit of a haul down here from the Boston area, but I have a 20-pitch three-blade Laser II and a VesselView Mobile, if you'd like to try them out.

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Picking out the right prop is actually a lot more challenging task than some would think. I would say in most cases the 3 blade prop will provide the highest top end speed, but depending on the hull that won't always hold true. A lot depends on the individual hull. Some boats that carry a heavier load up front will be faster with a 4 blade than a 3 because the extra grip of the prop will provide more lift. I would use the prop selector to get you in the ballpark, and then make a stop at a larger marine dealer in your area. Many will let you try props before you buy them. If it were me, I'd try a few, making sure I ran different series of props. Once you find the series that performs well with your setup, then you can fine tune the pitch going up or down pitches to adjust rpm to the desired range. Normally you want to prop your motor so under normal load you're running close to your max rpm. That's key to remember when you're testing the props too.  

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If your wanting the most top end speed stick with the three blade and change out to a aftermarket prop from a custom shop. Increase the size and pitch also add cup to the blades.

 

All my merc's run over their listed max rpm's so to correct that you need to increase the size of the prop i.e. go from a 12 inch to 12.5 or 13.

 

To make more speed add more pitch don't go more then 1.5 over what you have now, then run and see if you need more.

 

Add cup to the prop edge it will help reduce slip in turns and also help make a lil more speed.

 

Other then these things the only other things that can be done to make more speed is reduce weight in the boat or reduce the weight of the boat and do engine mods.

 

If it's a merc 2 stroke there are tons of engine mods you can have done.

 

I have a merc 2 stroke 40/60 Bigfoot model that is pushing way past 60 hehehehehe.

 

And my 50 on my tracker is pushing way past 70 hehehehehehe.

 

Powertech proper's are all I use, way better then factory ome prop's.

 

You should know I'm a speed freak lol.

 

Hope this helps you sir.

 

 

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Aluminum Tracker 175 TXW isn't known for speed with safe handling. I see a few tricked out with 6" jack plate and modified SST 3 blade props to race other Trackers and be 2 mph faster. If you want to go fast get a boat made to handle speed.

Tom

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I'm going to look at the tach again when I take it out. If it is 6000 rpm then is that the number I should use on the prop selector?

 

PECo, that's very nice of you to offer. Thank you. It is a little too far though. 

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2 hours ago, DanC said:

I'm going to look at the tach again when I take it out. If it ild0 rpm then is that the n umber I should use on the prop selector?

 

PECo, that's very nice of you to offer. Thank you. It is a little too far though. 

No use what is marked as max rpm on the motor's info plate then take that info and get ahold of a custom prop shop and tell them the size and pitch and the motor's listed max rpm, give them your top

speed with the prop your useing know and the rpm's it runs at in the water and they can tell you what prop size and pitch and how much cup to use to gain speed but also lower your rpm's back down to the listed rpm range.

 

Hope this helps sir.

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WRB,

    I'm not looking to go fast. Just to get the max speed out of it that I can and get the RPM down a little. I'm going to get a Laser II 20 pitch I think. I've found a few people online with same boat that say they get 42mph at 5500 RPM with this prop. This would be 2-4 MPH than I'm getting now. Usually I get 38 mph but have gotten up to 40 on occasion. I don't really want to get into modifications to the motor. Thanks everyone for the input.  

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Dan, I run a Laser II 48-16990, 20P on the my Optimax 115, Triton Tr-175. Heavier glass bass boat with more hp and top speed with 2 people, lots of gear, full gas tank and livewells at 56 mph. Being a 3 blade prop my boat is a little sluggish get out of the hole unless the engine is trimmed all they down. 

Good prop, you shouldn't have any issues other than a slower hole shot using the 3 blade.

Tom

 

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WRB,

     Thanks. Sounds like that is the trade off which I'm ok with. 

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On 6/15/2017 at 3:45 PM, WRB said:

Dan, I run a Laser II 48-16990, 20P on the my Optimax 115, Triton Tr-175. Heavier glass bass boat with more hp and top speed with 2 people, lots of gear, full gas tank and livewells at 56 mph. Being a 3 blade prop my boat is a little sluggish get out of the hole unless the engine is trimmed all they down. 

Good prop, you shouldn't have any issues other than a slower hole shot using the 3 blade.

Tom

 

56? That's mighty impressive for a 115 considering the load. Wish I was close enough to see that.

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I have a 14 pro team 175 with a four stoke 75hp.  Moved motor to 3rd from the top and a spitfire x7 17p.  Speedo says 45 GPS is 40-41.  Moving up to a 19p spitfire cause my RPMs are at 6000.  My opinion this prop is perfect with motor in 3rd hole from top.  Hole shot, speed, and handling is awesome.

3 minutes ago, Sam365 said:

I have a 14 pro team 175 with a four stoke 75hp.  Moved motor to 3rd from the top and a spitfire x7 17p.  Speedo says 45 GPS is 40-41.  Moving up to a 19p spitfire cause my RPMs are at 6000.  My opinion this prop is perfect with motor in 3rd hole from top.  Hole shot, speed, and handling is awesome.

 

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Sorry to bring up an older thread, but didn't want to start a new one.

 

I decided it was time to change my prop on my 2007 Tracker 175 with 2-stroke Merc 50hp, as my old prop from the previous owner had some chips in it.  My owners manual says max RPM at WOT is 5000-5500

 

My old prop is a black maxx 10.38 x 14P - 3 blade

My new prop is a Spitfire 10.3 x 13P - 4 blade

 

When I was WOT with my old prop, I was running 28mph at 5050-5100rpm

Now when I am WOT on this new prop, my RPM jumped to 6000-6100rpm and was still running 28mph

 

I am thinking about returning it and getting the same SpitFire 4 blade but back to a 14P.  My concern is that I was not expecting a 1000rpm difference in WOT with this new prop.  If I go back up to 14P, will I drop the 600rpm I need?  I don't think I will.  Any thoughts?

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You are obviously under pitched with your current 4 blade 13P prop. Going up 1" in pitch 4 blade will increase your speed if the engine can spin it 5500rpm's and that depends on boat weight balance, hull design and prop slippage factors that can't be calculated. if you can get a loaner prop, try it out.

Tom

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