Solas props

I have a Maxum 2100SR w/ 320HP 4 barrel 5.7 with 1.47 ratio Alpha 1. We were running a Powertech 14.5X19P aluminum 3 blade prop, and would run 4900 top end, but was starting to get some cavitiation burn on the prop. Last weekend switched to a Solas 19P 4 blade prop expecting to gain some low end grip and maybe give up a few hundred rpm on top. With the Solas prop and exact same load in the boat it would only reach 4300 rpm, and if you were cruising around 2500 and laid the throttle open, it would accelerate about 500 rpms, then start to bog down and stop accelerating. We are going to put the 3 blade back on thei weekend and see if acts the same as early in the year to rule out other mechanical problems.

Do the Solas props typically have that much more grip that it would pull it down that far? I didnt expect it to lug it that hard going pitch for pitch like we did? Judging by this last outing, we would need to go down to a 17 P Solas prop to get rpms back up around 47-4800.

Would a Michigan or Mercury 18P 4 blade act the same way?

The blade shape did look different. The powertech had what looked like a flatter less progressive blade and more rounded and softened trailing edge. The solas appeared to be more progressive, with a straighter and sharper cut trailing edge, and 'felt' like it had more cup in it, (thats subjective.). But, Just looking at them you would guess the Solas was a lower pitch.

Re: Solas props

Generally you go down 1-2" in pitch when changing from 3-blade to a 4-blade prop.

What is your top speed and what are you trying to accomplish?

Re: Solas props

The wot rpm and gps speed for both props would be interesting to see. When your testing the other prop.
Rpm doesn't really mean much without the gps speed.
Bogging down doesn't seem like a prop symptom.

Re: Solas props

I went from a 21 pitch 3 blade aluminum to a 19 pitch ss 4 blade and the wot rpm's were within 100 - it was like a new boat, great holeshot, lots of bite and I actually gained 1 mph on the GPS. It was a 210 Seville mid cabin, 260 merc with an alpha leg.

LK

Re: Solas props

Dont have GPS speed, but by boat speedo the Sola was down about 5mph, which may be about right having dropped 600 rpms or so.

It definetly felt more hooked up with the Solas, and not as free revving. When I say bog I mean it feels like its hooked directly to the water and not letting the engine accelerate. Like if you were going about 20 mph in you car locked in high gear and then pressed the accelerator to the floor. But if you acclerated modestly to 3500 or so it would pull on through pretty well.


One shop I talked to I told them I had a 19P aluminum and they said they would put me in a 16P stainless cause it would pull the engine down more, acause the prop would slip less.

Re: Solas props

So tell us your speed before the prop change and after the change some speed indication is better than no speed at all.
Need rpm and speed for both props.

Re: Solas props

powertech 19P 3 blade
48-50mph by speedo 4900 rpms.

solas 19P 4blade
44-45 by speedo 4300 rpms

Re: Solas props

You put your finger on it when you saw the blade geometry was different. All of those changes you see are there for a reason and the reason is performance. Could be that the performance is not the performance you are looking for aka speed vs work. More blades in the water is basically less efficiency because you have more paddles vieing for the same water. That's why dropping an inch of pitch from 3-4 is recommended with everything else identical....published data on that everywhere. However, the more paddles in the water under high load, moderate speed condition mean more control and sometimes better efficiency.

So my answer to your question is yes, you can have big differences in performance with different props of type and mfgr. Testing is really the only way you will know what is right for your rig.

Mark

Re: Solas props

You put your finger on it when you saw the blade geometry was different. All of those changes you see are there for a reason and the reason is performance. Could be that the performance is not the performance you are looking for aka speed vs work. More blades in the water is basically less efficiency because you have more paddles vieing for the same water. That's why dropping an inch of pitch from 3-4 is recommended with everything else identical....published data on that everywhere. However, the more paddles in the water under high load, moderate speed condition mean more control and sometimes better efficiency.

So my answer to your question is yes, you can have big differences in performance with different props of type and mfgr. Testing is really the only way you will know what is right for your rig.

Mark

Re: Solas props

Im not necessarily looking for speed, its just that i didnt expect that much of a change on the top rpms. From what I had read I was looking to see only a few hundred rpm drop going pitch for pitch. I wanted to try the 4 blade to help with low end and midrange grip and I think it definellyt helped that, becasue it felt really solid in the water. Maybe with the Solas design I just need to drop down to a 17P, keep the grip of the 4 blade but have even more power on the bottom end with the lower pitch.

I may see if I can find a MW or Mercury 4 blade 18P and compare blade design. I was tole pretty much all the aluminum props were basically the same design. But this Solas (my first one) sure seems to be manufactured a little different. Looks more like a stainless prop the way its machined and finished.

Re: Solas props

The Solas aluminum props are squeeze cast; resulting in props that perform very much like a SS prop.

And yes; you'd need a 17 pitch Solas 4 blade to get your rpm back up where it was.

You usually want to drop down an inch or two in pitch going from 3 to 4 blades in order to maintain rpm.

Re: Solas props

My suggestion to get close to your RPM max at WOT , the performance you need, and improved handling
at slow speed, would be a Michigan Vortex 14 1/2 x 18p 4 blade. Part # 992203. It will work. Have seen this same scenario dozens of times on this and other boards, my suggestion has worked everytime when comparing to a Solas propeller.

Re: Solas props

Thanks for all the advice, since I was just slightly over top of the rpm range anyway at 4900 I was expecting the 4 blade Solas to bring it down just slightly anyway, thats why i didnt drop any pitch. I will either try a MW 18P or go to a 17P solas.

Do Solas 3 blades act the same way? Meaning if I was to swap to a solas 3 blade at some point would I need to drop pitch as well. It was noticeable difference how well it held in the water. Where the powertech and michigan 3 blades I have had before felt looser but revved cfaster.

Re: Solas props

Put the 3 blade powertech back on last weekend, everything was back to normal. Engine pulled and revved like normal, so that pretty much narrows it down to the Solas prop causing the issue. It would just be interesting to hear if this is common with their props or if I got one mismarked or something I dont know. I have seen them reccomeneded several times so there has to be some experience with them.

What frustrates me the most is if this is normal there is nothing anywhere I have found stating that. If the design necessitates going down in pitch that much to keep your rpms up it would be nice to have known that up front. Luckily I bought it locally at a prop shop and can exchange it for a different pitch. If I had bought online expecting the pitch to be 'close' I would have been really ticked off and ended up with a useless prop that I couldnt return.

Re: Solas props

MBAKER said:

Put the 3 blade powertech back on last weekend, everything was back to normal. Engine pulled and revved like normal, so that pretty much narrows it down to the Solas prop causing the issue. It would just be interesting to hear if this is common with their props or if I got one mismarked or something I dont know. I have seen them reccomeneded several times so there has to be some experience with them.

What frustrates me the most is if this is normal there is nothing anywhere I have found stating that. If the design necessitates going down in pitch that much to keep your rpms up it would be nice to have known that up front. Luckily I bought it locally at a prop shop and can exchange it for a different pitch. If I had bought online expecting the pitch to be 'close' I would have been really ticked off and ended up with a useless prop that I couldnt return.

Click to expand...

Paying a little more and being able to get what works is money well spent as you realized.

All the data that shows up on this site indicates that you want a 4 blade prop for stern heavy, heavy water toys, or low speed cruising. Not only does it keep you from having to continuously jack the throttle around people have remarked that it makes the boat easier to control from a steerage standpoint. So I would stay with the 4 blade prop that works for you.

Mark

Re: Solas props

You came to Iboats for free advice, and you got your money's worth LOL...

It is difficult to compare one prop to another when changing brands, rake/cupping, and blade count all at the same time. And your experience describes is the very reason I like and often recommend Solas props, and why it is often very important to test-drive a prop prior to purchase, and why it is a risk to buy without a return policy. It sounds like the Solas bites the water better and is more efficient than your Powertech. RPM reduction is a favorable thing. And if your speedo is accurate, your numbers further prove this to be the case. In a prop slip calculator, your first prop calculates to about 18% slip, and the Solas prop calculates to about 14% slip. Less slip is always the goal in prop shopping.

This means IF you get the correct pitch, the Solas prop will be more efficient, will perform better, provide better fuel mileage, and give you better acceleration and speed. You simply purchased the wrong pitch for your boat on the first try, and it sounds like an exchange/return was not too difficult for you....so no reason to be frustrated or anything because you got a great education and didn't even lose any $$. All's well that ends well...

Based on the knowledge you have now, I'd confidently recommend a 17 pitch Solas in the same style you just tried in a 19. That should bring you right up into the 4700 to 4800 range and give you great holeshot. Trying an 18 in a Michigan Wheel or whatever will be another experiment into the unknown, and the results will be less predictable. Michigan Wheels are much less aggressive props when compared to the Solas.

Re: Solas props

agreed ^
It appears the power tech has about 18% slip at 48 mph. The Solas 4 bld. is at about 14% .
18% is high The 14% is high normal. And at only 4300 14% slip is a excellent number.
I think a 17" solas 4 blade should produce about 4700 with about 10 to 12% slip.
Still less speed than the power tech but all around better performance but for the speed.
The 4 blade 17" should have excellent hole shot, stay on plane easier at reduced throttle,will seem smoother,
and should respond better around the dock.

Re: Solas props

I knew there could be some difference switching brands just didnt expect it to be this much. At lower engine speeds it had to be even lower slip numbers with the solas, because at 2500 cruise if you try to accelerate fast it would almost kill the engine. Thats the part I didnt expect, and did not find any info online pointing to that. I talked to solas rep and he suggested that even going 3 lbade to 3 blade he would prob suggest dropping 1-2" of pitch from the powertech to keep same rpm, let alone going to 4 blade. To get my rpms back up where I want them I feel like I would need to go to a 16P in the 4 blade at this point. That would get me back to about 4800 where I want to be.


The thing is the boat sure seems to run/work better with the powertech and more slip, even it if shouldnt on paper. It pulls from a start easier and seems to make better power, my guess is because it lets the engine rev faster in to the powerband, especially pulling a skier. But I dont know what it would do with a lower pitch solas either, I dont really have good acceleration 'feel' with a solas prop to compare with. The whole reason I tried the solas (actually 4 just a 4 blade) was because of the cavitation problem with the powertech taking paint off, which im guessing is due in part because of the slippage.

Re: Solas props

just a couple questions for me to ponder over...


In you alls experience would a Mercury, or MW run more closely to the Powertech or the Solas? The original prop spec'd for this boat from manufacturer was a 21P (mercury), we have been running a 19P because of the heavier load. So based on that im guessing the mercury props would perform similar to the powertech but could be wrong. Im not saying any one is better than the other, just mostly for future reference and comparison sake.


On my powertech to Solas swap, is the difference in slip due to the solas design, or is it due to the 4 blade vs 3 blade. Meaning would my slip % go down no matter what just due to the extra blade and no matter what brand.

Re: Solas props

Hard to answer that last question. Everything is pure speculation untill you do your rig setup, and run the prop you think is right. That's why sometimes to pay a little more and get a supplier to swap props until you max your reqirements. Obviously you will pay more, but once you spend the money it is gone. The satisfaction is with you as long as you have the rig.

Mark