SS Prop benefits

[cretus]

I bought a new 175 SC Bass Tracker a few months back and opted for the standard 90HP 4 stroke instead of the optional 115 hp. I compared the statistics of the two engines and the 115 would give me only 2 more MPH and burn twice as much fuel at WOT. After a few trips to the lake I feel I should have went with the 115. With the 90 the boat feels like its lacking. It delivers the maximum 40 mph as listed, but Struggles to get on a plane with two more people on board. Someone actually has to get on the bow to get the boat down. Once on a plane the boat runs in its RPM range, but feels like I'm towing a boat behind me. My question is is there a noticeable difference in going with a stainless prop and ditching the stock aluminum prop, or is it a waste of money? The boat has noticeable cavitation problems in the slightest turn, and I mean slight, when Its on a plane. Any ideas would be appreciated.

 

[Texasmark]

Re: SS Prop benefits

You could go with the same pitch SS. Get one with high rake, cupped, and ported. You asked the question here is the answer. They have great deals on here. Read the details of the advertised prop to see what it's attributes are and sometimes they say what they are designed to do.

Mark

 

[RogersJetboat454]

Re: SS Prop benefits

Are you adjusting the motors trim while trying to get on to plane?

 

[jestor68]

Re: SS Prop benefits

What is your WOT rpm reading at 40 mph? If you're not propped at the top of the rpm range(6000), performance with the 4 stroke will be on the sluggish side. Also need the prop size and brand for a reference.


In reference to fuel economy; according to engine tests posted on the Mercury web site, there isn't that much difference. On like size boats at WOT, the 115 used 10.3-10.5 gph. The 90 used 9.6-10.3 gph.

Sounds like the "twice as much gas" myth may have been a sales pitch to sell you the standard package that was on the floor.

 

[jsimms724]

Re: SS Prop benefits

s/s looks better

 

[cretus]

Re: SS Prop benefits

I start with the motor all the way down an bring up the trim as I accelerate. My WOT at 40 is around 5600. To get to 6000 I have to trim the motor to high and start to loose bite. I should have gone with the 115, but I'm stuck where I'm at now.
I ran the prop selector on mercury and they chose the laser II.

 

[jestor68]

Re: SS Prop benefits

You need 400 more rpm at WOT. That means you need to drop 2 inches of pitch from whatever is on there now if staying with aluminum.

Don't rely on ANY prop selector to give you the correct pitch. They are only suggestions(read the fine print).

Use your base line and adjust from there. Figure on 150-200 rpm for each inch of pitch. Switching from aluminum to SS adds another factor into the equation. For example, when switching from al to SS, it's required to drop an inch of pitch in order to maintain the same rpm.

So what it boils down to is drop 2 inches to gain 400 rpm, and drop one more inch if switching stainless in order to keep the rpm at 6000.

For what it's worth, Solas aluminum props perform as well as some stainless props. Actual tests I have seen showed the Solas aluminum prop side by side with the stainless up to top speed; where the SS beat it by 1/2 mph. That test was on an aluminum boat similar to yours.

 

[cretus]

Re: SS Prop benefits

Well it is obvious that I'm out of my area of expertise when it comes to props. I'm guessing the prop that came on the boat is a general size they just throw on the motor based on the hp and not the boats needs. Heres what I got from the mercury website. It says that the operating range is between 5000 and 6000. I felt safer running at around 5500 and never really pushed the trim higher. At the 5500 throttle range the boat felt the best in speed and handling. I'll have to admit that running closer to 6000 I had a bit of fear of over reving the engine. I'll have to check it on the next trip and see if there is any difference at the 6000 mark.
Jestor you are here in Georgia. Is there a place to take the boat and have a professional test the boat and recommend a prop. I feel it would be in my best interest to go that route since I have a problem with the "if its bigger and costs more it has to be best" thought process.

 

[jestor68]

Re: SS Prop benefits

Jestor you are here in Georgia. Is there a place to take the boat and have a professional test the boat and recommend a prop. I feel it would be in my best interest to go that route since I have a problem with the "if its bigger and costs more it has to be best" thought process.

If you bought a new boat, I'm assuming you bought it from a dealer. You could take it there and tell them that it's only getting to 5600 rpm at WOT and has a poor hole shot.

They should advise you to drop to the next lower pitch(usually 2 inches) to get your rpm up to the optimum for your 4 stroke motor. You can't over speed the motor to the point of damaging it, as it is equipped with a rev limiter that won't let it go past about 6200 rpm. You would be surprised how much difference 400 rpm can make in the overall performance of a boat.

Your profile doesn't say where you are in Georgia. If you check my profile, you might consider me qualified to take a look at your rig. Are you anywhere close to Columbus?

The Mercury Marine web site has a listing of dealers. Depending upon where you live, there may be one nearby.

 

[jestor68]

Re: SS Prop benefits

I feel it would be in my best interest to go that route since I have a problem with the "if its bigger and costs more it has to be best" thought process.

Yes, you run the risk of any dealer telling you that you need this fancy stainless steel $ 450 prop when one of the latest design aluminum props by Solas or Turning Point would work just fine.