What prop to use for a 175

[dutchman]

I’m trying to gather some info on what other owners are using.
My boat came stock with an Aluminum 14.5 x 19”. It performs quite well, pulls good, WOT of 4800, so it’s working like it should. Pulls an adult slalom skier or a couple tubes without a problem. But I’m always looking for an improvement.
So I picked up a SS High-5, since they’re supposed to be the best for pulling toys or skiers. The one I picked was a 13.25 x 19.
*The WOT is 4750.(lost 50 rpm)
*At specific rpm’s across the board, it was only 0.5 mph slower than the aluminum, except at WOT, lost 2.5 mph. (using GPS).
*I can keep on plane at lower rpm/speed with the Aluminum (which really surprised me).
*Pulling out of the hole, was no improvement.

So if the Aluminum is working almost perfectly, is there no room for improvement?
What else can I try? Or does it sound like I'm about as far as I can go?
My elevation is 3000' if that matters.

Since this varies so much between boat models, I was wondering what you 175 owners are using and how it works.:smt101

 

[Lazy Daze]

The reason you're not having much luck with the Hi-5 is a simple matter of engine torque vs weight of prop. As I'm sure you noticed, the Hi-5 (and any SS prop) is markedly heavier than an Al prop. The 4cyl just doesn't have enough power (torque) to spin the SS prop quick enough to be able to take advantage of it's inherent benefits. I found this out about 12 or 13 years ago when I had a boat similar to yours - I experienced practically identical results.

If you want a faster hole shot via a prop, drop pitch and/or go to a 4-blade Al prop. Just remember that you will also lose top end speed and could over-rev the motor.

A great, all around solution, is to keep your current prop and add a set of Smart Tabs. That will give you a noticeably better hole shot and also an improved ride (less bouncy). They run under $150 and take about an hour to install.

 

[adamgll]

Lazy is correct.

In fact even with a 6 or 8 cylinder with plenty of torque the Stainless will not always out accelerate the alum. The stainless shines in top speed (roughly 2mph quicker). I am talking about 3 blade set ups.

 

[dutchman]

thanks for the comments.....I have read a ton of good things about the H5, but I don't know anyone that has one on a 3.0L. I figured the best way is to try one and see what happens. Obviously it doesn't improve anything for my application.
There's nothing wrong with what I have, but it's always fun to experiment to make it better. Oh well, at least I can spend my $500 on something else.

 

[adamgll]

thanks for the comments.....I have read a ton of good things about the H5, but I don't know anyone that has one on a 3.0L. I figured the best way is to try one and see what happens. Obviously it doesn't improve anything for my application.
There's nothing wrong with what I have, but it's always fun to experiment to make it better. Oh well, at least I can spend my $500 on something else.

you can always get a laser II in the same pitch and add smart tabs and pick up few mph up top and have just about the same acceleration.

 

[Mikeyf]

That's interesting, you say your boat came with a 19" prop. Mine came with a 21" Al prop. Unfortunately I've not played too much with my boat as I only purchased it late last year and don't use in the winter months. And sod's law came a knocking last weekend, in that I struck something totally submerged, nothing hit the hull but I did hear and feel the strike on the prop. Fortunately no damage to the engine, but the prop is now missing half a blade. See Pic.
I'm trialing a 21" high Five this weekend as I've found someone nice enough to loan me one. I've seen the other guy's comments now but will try anyway and feedback.

 

[AR185]

I've had excellent results with the SS mercury Inertia prop on my 185 with the 4 cylinder.

 

[Mikeyf]

Well guys I've now tried the 21 high five for a few weeks and its running great. Spins up to speed and gets on the plane within a few seconds and continues well up to 40mph. (checked with gps.) Also much between turning 'circle' without dropping out. Would recommend it to everyone.

 

[surfinjoe]

+1 For smart tabs. My 180 Sport (same as your boat) had a huge improvement. So much so that I even put a set on my 220 SD.

 

[Lazy Daze]

97Alpha, this thread isn't really about stock props - read the first post and you'll see what I mean.

However, go look at the prop matrix on SR's website under the Owner's section. Look at your boat/year. 21", though, sounds about right for stock.

BUT... that doesn't really matter, especially with an older boat. How does the boat perform with your current prop? That's MUCH more important. If you've ben searching around for prop info, I'm sure you've came across recommendations about this... run the boat with just you as fast as you can go with it trimmed as high as possible till speed no longer increases or the prop starts to ventilate. What RPM's do you get to? By now, you should also already know that your max RPM is 4,800. It's OK, though, to go a couple hundred over that for testing purposes (short time only) if needed. Once you have that, then you'll know what direction to head in terms of a proper prop.

 

[97Alpha175]

97Alpha, this thread isn't really about stock props - read the first post and you'll see what I mean.

However, go look at the prop matrix on SR's website under the Owner's section. Look at your boat/year. 21", though, sounds about right for stock.

BUT... that doesn't really matter, especially with an older boat. How does the boat perform with your current prop? That's MUCH more important. If you've ben searching around for prop info, I'm sure you've came across recommendations about this... run the boat with just you as fast as you can go with it trimmed as high as possible till speed no longer increases or the prop starts to ventilate. What RPM's do you get to? By now, you should also already know that your max RPM is 4,800. It's OK, though, to go a couple hundred over that for testing purposes (short time only) if needed. Once you have that, then you'll know what direction to head in terms of a proper prop.

I am going to edit the previous message down as I realize it did not really belong/apply here.

Factory 1997 3.0lx 175 had a 14.5 x 21P as per https://owners-resources.searayweb.com/propeller-charts.html (thanks for the lead Lazy Daze!!) Mine currently is a 14.25 x 21P

I personally just bought my boat literally. When on the water buying the boat, the rpm gauge was sporadic so I did not go WOT. Until I work these things out I will not be back on the water. Ran great though, when tach looked accurate I was cruising around 3500 at 23-25 maybe, I did not note these numbers.
If the boat had originally a 14.5" prop and now has a 14.25" why the change? Seems opposite of what most people would want. But it ran fine (handled great through sharp corners maybe b/c the 14.25). If I understand correctly smaller diameter will end up working the engine harder assuming I drive at full throttle... Huh, well I appreciate the lead on the prop website. That gives me the starting point I wanted.
If you have anything to ad to this I appreciate it!

 

[Lazy Daze]

1/4" in diameter isn't going to mean a whole lot in the real world for this particular application. Besides, different props can be cupped different, as well. There's a bunch of variables that go into making a prop so don't get overly caught up on the specs. Be aware of the specs, but unless you're comparing the exact same brand/model of prop, use the specs as more of a general guideline. The important part is how it makes the prop perform,

Once you get back on the water and get some data, then you can post back (maybe start a new thread to keep it easy) any questions you may have... if any.

Tach bouncing... pull the tach out and slide/rotate (depending on model) the little selector switch on the back a bunch of times to clean the contacts. Make sure to leave it on "4". That might help.