Boat prop: stainless, 4 or 3 blade,pitch?

Need to get a new prop and likely send another in for refurbishment. Boat is Lund Explorer 1825 made in 2010. Engine is 115 Merc fourstroke outboard from 2012. Shredded a 3 blade prop last fall on a tree limb, and scraped up a fin on the replacement 4 blade prop I put on to run this spring over the weekend. previously the 3 blade aluminum prop would push the boat about 38-40 m/ph in ideal conditions (2-3 adults, 30 gallons of fuel, gear), had no problem with getting on plane but not an immediate holeshot burst and maxing out at 6000-6100 rpm’s. With the aluminum 4 blade backup on i was getting 35-38 (same conditions as previous) but a stronger hole shot and maxing out at 5800 rpms.

Thoughts on staineless? 3 or 4 blade? Other thoughts besides quit damaging props?

You hit something or chewed up two props just last year. I would not suggest stainless unless you want to replace way more than a prop in the future.

Generally speaking a 4 blade prop will give you better hole shot and control while a 3 blade will offer higher end speed.

I don’t understand the pitch/angle thing on props. Maybe someone else can chime in with some advice on that.

I can only give you my experience. I have an 18.5ft aluminum boat that came with a stainless 3 blade 19 pitch. It was maxed out at 5500 rpm and I was getting some blowouts while trimming and turning. Hole shot was also not impressive.

I put a Merc Spitfire X7 17 pitch on it and it was a big difference both in hole shot and handling. Also it bumped up my RPM to 5900-6000. I think I might have even been able to go down to a 15 pitch since technically I can max out the PROXS at 6250.

I think it was well worth it and I just kind of shrug my shoulders at the guys who think you shouldn’t run SS around suspect areas. I run the MN and MISS 95% of the time and hit logs often. Instead of replacing props, I just turn most of the wood into mulch. The sacrificial hub will be the first to fail if I hit anything hard enough.

I would never buy an aluminum prop again.

One last fall and one this spring…technically

Sounds you need to make the decision on which you liked more? Some guys think it’s more important to get ever MPH our of their motor, others like to cruise along at 4K RPMs.

Either way, it seems like you’re in the recommended max RPMs with either prop. The 4 blade must have been pretty close to the same pitch? Normally you’ll drop about 2-300 going from a 3 to 4 blade.

You honestly wont see a significant difference in performance going from Alum to S/S on a 115HP. You’ll have some flex with alum. but nothing major.

I didn’t see any mention of prop pitch in your message. What are the props, 15″?

Ripjiggen wrote:

You hit something or chewed up two props just last year. I would not suggest stainless unless you want to replace way more than a prop in the future.

I believe Mercury hubs are intended to spin out if you hit something solid so I would think stainless would be fine.

This link should get you started, but I would recommend talking to a reputable prop shop in your area. They often have a good idea based on past experience with similar boat/engine combos. I worked with Brainerd Propeller and have been happy with their advice.

Mercury Prop Selector

Count me as a +1 in the group that says the added cost of a stainless isn’t going to give you a significant performance upgrade over aluminum on a 115hp outboard and fishing boat. Playing prop roulette is expensive and time consuming and one more thing to waste time. I too run a 115hp outboard (on a 17′ fiberglass boat) and if I damaged the existing prop, I would go buy the exact same one tomorrow. I know it works, I know how it handles, and I’d be back fishing without any tinkering or trial and error.

My tritoon came with a stainless prop on a 150hp outboard. I really doubt I’m seeing a major performance difference on that rig either. If I wouldn’t have bought it used and 2 years old, I would never have paid more for the “upgrade” to a stainless on a 150 either.

TillrLife wrote:

You honestly wont see a significant difference in performance going from Alum to S/S on a 115HP. You’ll have some flex with alum. but nothing major.

This is everything…

It’s not all about performance. When I had an aluminum prop I was replacing or repairing it at least once a year. I’ve now had a stainless for 4 years and still looks new.

I’m a SS believer but thats my preference.
What do you like the hole shot or top end speed?If your going to go SS i would try one first if possible.I’m not sure what your max rpm’s are,around 6000 i believe so you would want to be in that 5500-6000 range at WOT.

Floating Wood the stainless steel will usually dice up. Now if you hit rock, or a rooted hardwood stump, even with the hub designed to give first, you’ve got a much better chance of bending the prop shaft. Which is a lot more money, plus shop time.

Stainless turning point 14x17p is good for me. I’d love to get my hands on the Merc spitfire x7 in a 16P.

4 blade Merc spitfire (quicksilver nemesis is identical) is an awesome aluminum option that claims to offer holeshot without top speed compromise. I can vouch for this after actually testing my own rig, the spitfire/ nemesis gives better holeshot and top end than the black max in the same size.

I went down the rabbit hole of prop theory very deeply over the last few years. I learned a great deal, and have a fair understanding, but it would take hours for me to relay the info. After 4 stainless props and multiple visits to a 45 year pro prop guy with my current boat/motor, I now know enough to make a fair guess.
If your reading comprehension is good, read the story at the following website, and you should gain enough understanding to know prop choice has a TON of variables. And very few props are actually accurately blueprinted from the factory, which doesn’t help during the trial and error process. Good news is that if you buy used props in very good condition, you can almost always recover your money if you have to resell them. Lots of scams on Marketplace & FB Groups – be cautious.

http://kencook.net/Setupart.html

I had a Lund pro Guide 1775 with a 90 merc and when I switched out the Spitfire aluminum to a Spitfire stainless, the difference was dramatic. More bow lift, more acceleration, higher top speed, and an inch higher engine height. Fantastic prop for those engines.

I’m not sure if the smaller mercury 4strokes do it but my 200 Yamaha has bad prop chatter with a stainless prop on it. I believe there’s a hub merc makes that will stop that. I think it is called a flow torque hub. Something to look into anyways. I can vouch for stainless props being very unforgiving. It doesn’t take much at all to bend a prop shaft.

Musky Ed wrote:

I had a Lund pro Guide 1775 with a 90 merc and when I switched out the Spitfire aluminum to a Spitfire stainless, the difference was dramatic. More bow lift, more acceleration, higher top speed, and an inch higher engine height. Fantastic prop for those engines.

Did you switch out the prop for the exact same version that you previously had with aluminum? I’m only asking because if I was to do this, that’s where I’d start too.

Musky Ed wrote:

I had a Lund pro Guide 1775 with a 90 merc and when I switched out the Spitfire aluminum to a Spitfire stainless, the difference was dramatic. More bow lift, more acceleration, higher top speed, and an inch higher engine height. Fantastic prop for those engines.

You’d have to compare the exact same prop to make this statement, which is nearly impossible. You saw higher performance because most S/S props have completely different features, one of those will create more bow lift. Plus, you lifted your motor up higher(extra 2-300RPM), so you’ll see higher RPMS, so higher top speed. A S/S prop can be raised higher because it will not cavitate as easily as Alum.

It’s great you got the results you wanted, but those results are not all created equal. I put a 17″ Alum. prop on my G1 Etec 90 HO(115HP V4), prior to that I had a 17″ S/S, I saw higher RPMS and gained 2MPH. Why, because the diameter on the S/S was larger, more suited for a bay boat.

Also, when talking max RPMs, you want to be as close to the top end as possible. The range is there for a guide, but if that range is 5500-6100, you want to be as close to 6100 as possible. You will (pretty much) always see better performance in your boat if you are closer to the high end than even 5700-5800. That means you’ll will consume less fuel at cruise(3500-4000RPMs) and even have a higher cruise speed.

I disagree wholeheartedly about no performance gain with ss on a 115.
Here is the link to my prop conversion I did on my 90hp 4 stroke mercury.

http://www.in-depthoutdoors.com/community/forums/topic/1675-impact-prop-selection/

Took the boat to a local lake, no traffic at all.
Ran a half dozen straight baseline runs from 0 – 39.8 at 5700 in 20-21 seconds
Pulled the prop and torqued down the PowerTech.
Ran a half dozen straight baseline runs from 0 – 40+ at 6000 in 15-16 seconds
Motor actually hit rev limiter just shy of 6200 at almost 43 MPH
but that is with just me on board (prop selection is for 2 on board)
The boat gets on plane noticeably faster as well.
The handling is a lot batter. I can crank the wheel to lock in either direction without having to change the prop trim or back off full throttle .

Big thanks for the recommendation Propmann

After reading all of the above, I feel like I know next to nothing with props. This is going back a ways when my dad owned a Trophy 170 with a 90 on it, we switched to a stainless steel prop and it was like night and day. Hole shot was crazy good, we could pull two skiiers out of the water easier than my friends boat could pull one, and it had a 115. We also gained easily 5 mph top end. But I was just a stupid teen and didn’t pay attention to the prop angle or anything like that. But in the long run, for us, it was better in every aspect to have the stainless steel prop.

Looking up the part number my 4 blade prop was a Merc Spitfire 13×17 RH

$607 out the door for a new Mercury Spitfire X7 13×17 and refinishing the aluminum one for a backup.

acarroline wrote:

$607 out the door for a new Mercury Spitfire X7 13×17 and refinishing the aluminum one for a backup.

Who’d you go with for new prop and fixing the old Alum prop? Thanks

600 bucks to gain 3-4 mph ? I mean damn , maybe if I’m fishing the ocean running 100 miles. Biggest performance upgrade for my boat on speed is 1/4 tank of fuel and just me vs full I’ll gain 3-4 mph ha .

I’ve had over 50 years experience playing with props on all types of boats, many aluminum boats, go fast bass boats , bay boat, and multiple walleye boats so I’ very familiar as to what causes what and what changes affect what.
As to that Lund, yes I changed out to the same prop in stainless, a 17″ version. I actually think that boat should use a 15″ version whether it’s aluminum or stainless. I went with the same size as I thought with raising the engine a hole I would gain a few more rpm than I did. If I had kept the boat I was going to try and find someone with a 15 that wanted to trade for my 17, and then would have lowered the engine back down a hole to where it was originally. If I remember right, even with the engine height change, there was only a small rpm change of a hundred or so. If you are looking for a larger rpm change drop pitch.
Sadly I sold that boat as I needed some garage space as it was a second boat for me, and with two boats and two vehicles and a three car garage, I wasn’t able to talk my wife into parking her car out in the winter.
Somebody got a fantastic little boat. Actually, was in some back and forth talks with a longtime member on here about him buying it, but someone local committed before him. He missed out on a great boat.

As ripjiggen said.you will have way more problems if you put on ss prop keep it aluminum I would never go stainless ever! Is your motor under powered? Or do you just like the shinny look? If you hit something you might just find out the cost the hard way,already have wrecked 2! if you only run lakes your chances are better but why risk a insurance claim.

There are days where I am by myself with 1/4 tank of fuel and a handful of rods. There are days where I have 3 people in the boat, a full tank of fuel, a cooler, everyone’s gear, and a full livewell. There are just so many variables to start throwing money and time fine tuning props for a 17′ fishing boat that it’s not worth it for me. As previously stated, in a fishing boat this size if my prop got damaged I’d pull it off and go get an identical one tomorrow.

To the OP…I’d go buy whatever you last had on and get back to fishing.

Alagnak1 wrote:

<div class=”d4p-bbt-quote-title”>acarroline wrote:</div>
$607 out the door for a new Mercury Spitfire X7 13×17 and refinishing the aluminum one for a backup.

Who’d you go with for new prop and fixing the old Alum prop? Thanks

Prop Depot for purchase, had a connection. Refurb will happen with a local dealer.

isu22andy wrote:

600 bucks to gain 3-4 mph ? I mean damn , maybe if I’m fishing the ocean running 100 miles. Biggest performance upgrade for my boat on speed is 1/4 tank of fuel and just me vs full I’ll gain 3-4 mph ha .

Not quite the generalization you’ve come up with….

Aluminum was gonna cost about $250 as I needed a second prop regardless. Hoping stainless improves performance, but also hoping it eliminates replacing/refurbishing as often.