Anyone running a S/S four blade prop

[Axl]

I am looking into re-propping my boat and I am wondering of anyone is running a S/S four blade prop or has gone from a 3 to a 4 and would like to share their experience. I have spoken to two prop shops on the phone both based on the sunny coast so most will know who they are, one has recommended a four blade and the other a three.

My rig specs are as follows, CW 1750 Whittley dry hull weight of 670kgs fully loaded weight of around 1100-1200kg with a 2016 Yamaha 4 stroke F100LA bolted on the back. Currently this has a standard alloy Yamaha prop 13.25 X 17K which is revving out to 6100-6200 very easily. When I push the throttle forward she jumps up out of the water no worries and will be at max rpm within 30-40secs, max rpm range for these motors is 5000-6000rpm.

I have tested a S/S 13 X 19 that my local boat yard lent me and at WOT this prop brought the max rpm back to 5500, both myself and the mechanic would like to see the rpms at WOT between 5700-6000. Once I start testing and decide whether I am going to use a 3 blade or a 4 blade this will be the bench mark I am looking for.

My main reason for changing the prop is to get the motor running at the correct RPM for longevity, speed and fuel burn aren't a great priority. Fuel burn is already good as I am getting better than 2klm a liter at cruise speed and this should improve slightly with either of these props, top end speed doesn't worry me never has and never will. I will be more than happy at the top end speed either of these pros have to offer.

[Noelm]

Why do you think you want or need a 4 blade? For what you want, I would contact Solas and get them to try a few different props before you decide.

[Axl]

I would contact Solas and get them to try a few different props before you decide.

Did that, that is where the recommendation for a four blade came from.

[fishizzle]

I went from a 3 blade to a 4 blade on a 60hp pushing a 4.5m ally centre console. I dropped 900rpm at wot and lost approx 5Kn off top speed. The boat planned at much lower speeds and got out of the hole a lot better. The lower planning speed was good for trolling and going slower in rough weather. Both props were same pitch and diameter. If I was to have my time over I'd probably just go with a 3 blade and fit a foil.

[rexaway123]

When you go 4 blade from 3 you have to drop a pitch or 2 or you will lose too much rpm

i went down 2 when I switched to 4 on my noosacat

made huge difference for better in my situation changing
not sure about yours

[Magilla1]

Had a 3 blade and foil that I wasn't happy with in regards to hole shot so fitted a four blade. Left the foil on and dropped a pitch. Lost a little top end speed but happy with hole shot and as others have said, trolling at lower speeds a bonus.

[scottar]

There is a lot more to it than just the number of blades. I have tried 3 different 4 blades and then gone back to a large bladed 3 blade. I was looking for a specific set of parameter improvements - low speed planing and fuel economy. It is a matter of trial and error coupled with how deep your pockets are unfortunately. Someone like Solas will be good enough if you aren't looking to extract every last bit of performance as the costs to try different props are negligible. You won't necessarily end up with the absolute best prop solution but it will be good enough given the outcome you have described.

[Axl]

Had a good chat with the guys from Ozpropellers today and I am now leaning towards a 3 blade S/S Powertech RED3. We are not exactly sure what pitch will do what I require as yet but we are going to start with a 13.25 X 15 and see where the rpms get to, as most will know it is a case of trial and error till you get as close as you can to the target. I may need to go to a 16 but we will have to wait and see.

From the info they gave me on these props they sound like they are a terrific all round prop with moderate rack and cupping allowing them to bite the water well. Going to go and have a talk to them face to face next week when I fly home from work.

The other prop dealers mentioned above were very pushy when I spoke to them on the phone and wouldn't let me get a word in edge wise, I sent them an email asking for more info after our chat and they haven't bothered to reply so they certainly wont be getting any of my hard earned.

[Flex]

the Yamaha is rated to 5000-6000 rpm for its rev range. You sure its going to do damage at 5500rpm? specs say its fine. (maybe test to see if you make oil between 100h services to truly see if its doing damage?)

id compare the props at your cruising speeds and see how they differ as that's more important generally. (As long as it makes recommended rev range)

There is one dude at solas who's a pain in the ass to deal with. Doesn't shut up and let you talk. Also they are big proponents of 4 blades for some reason no matter the boat.

I had 15's on my f115 Yamaha sharkcat. I was hitting above 6000rpm inside 10 seconds of take off.

Went to a set of 17's in four blade. Get approx. 5700rpm and approx. 10km/h faster cruise, but with 4 blades ive noticed when going from 5000rpm to max you don't get as much speed increase as a 3 blade.

Also much less cavitation heading downwind with the 4 blade.

[Axl]

the Yamaha is rated to 5000-6000 (tel:5000-6000) rpm for its rev range. You sure its going to do damage at 5500rpm? specs say its fine. (maybe test to see if you make oil between 100h services to truly see if its doing damage?)

id compare the props at your cruising speeds and see how they differ as that's more important generally. (As long as it makes recommended rev range)

There is one dude at solas who's a pain in the ass to deal with. Doesn't shut up and let you talk. Also they are big proponents of 4 blades for some reason no matter the boat.

I had 15's on my f115 Yamaha sharkcat. I was hitting above 6000rpm inside 10 seconds of take off.

Went to a set of 17's in four blade. Get approx. 5700rpm and approx. 10km/h faster cruise, but with 4 blades ive noticed when going from 5000rpm to max you don't get as much speed increase as a 3 blade.

Also much less cavitation heading downwind with the 4 blade.

I wouldn't think any damage is being done at 5500 but as you have said I'd like to see it closer to 6000 than 5500. The loan prop that gave me the 5500 at WOT is an old black painted S/S unit and I can get a brand new prop spending a touch more than the price they want for it.

[robothefisho]

If all you want to do is lose a couple hundred rpm, just cup the prop you have now. Will pick up a bit of speed and get more grip. Cost about $30.

[Axl]

If all you want to do is lose a couple hundred rpm, just cup the prop you have now. Will pick up a bit of speed and get more grip. Cost about $30.

Yep great advice thanks, and I was also thinking last night that if I simply buy the next size up standard alloy Yamaha prop which is 13 X 19 at a potential cost of around a couple of hundred this would also achieve what I am after.

Then the next thought is, 6 months ago you outlaid well over 40k so in the scheme of things an extra 600-700 to help something perform to its optimum isn't all that big of a deal. It never ends with boats does it.....:o

As is said BOAT= Bring Out Another Thousand ;D

[The Black Unicorn]

If it's a 17k prop on your boat then it is a stainless prop. Don't be fooled by the black paint. I had the same prop on an F115 Yamaha and was getting 6000 rpm easy but fuel economy was crap. Ended up going a solas 13 1/4 x 17 New Saturn. My WOT dropped to about 5500 -5700 depending on load but my top end speed picked up a bit and my mid range was great. Fuel economy went from 1.5/1.7 km/l to 2/2.2km/l. If you're getting 6200 this may be a good match? IMO the 17k props just don't have the surface area.
The upside of dealing with Solas is they will allow you to swap props and test them until you're happy with your results.

[goona]

I have had few different experiences . 1st boat I was running a 135 Merc 2 stroke with a 3 blade ali prop. Cant remember hat pitch but changed to a 5 blade stainless, Totally changed the boat, Was 15% better on fuel and didn't bog down when we hit a wave like the ali did. My current boat was running a 17 pitch 4 blade and went to a 15 pitch 4 blade stainless and dropped 2 knots in speed but got up on the plane quicker and was using 10% less fuel which means Ion our Stanage trips we got another 50klms of range, Awesome if you are away for a week at a time.I also changed on my Honda 20 from the standard 4 blade ali prop to a 3 blade stainless. nt much different. Little less in speed but got up on the plane quicker. about the same in economy

[One Day]

Have you run your on water tests with the usual weight you would have in the boat on a typical day out? Number of people, gear, full tank etc will all affect your max rpm. You will want your RPM in an acceptable range when carrying your normal load and you may find it is set up just fine when you do this.

I have changed from a 3 blade s/s to a 4 blade s/s prop but it was to improve performance characteristics. I had too much cavitation on the deep v hull with the prop slipping when trimming out and the boat would slow down when hitting larger swell and waves which made it uncomfortable in rougher weather. The change to 4 blade (dropped a pitch or two) helped immensely. The boat has much more torque powering straight through swell with no loss of speed, has provided more lift to the hull and no longer has cavtiation issues (was even able to lift the engine height up one hole). The downside is that it did drop some 3 knots off the top speed but that was expected and for blue water fishing I wouldn't go back to the standard black yamaha prop.

As you don't have any real issues apart from the higher RPM I would suggest as others have getting some cupping put into your existing prop (cheapest option I would imagine) or trying out some similar props with one inch more pitch. Hope this helps.