I spoke to Jared yesterday and I have the SCE5 - 15 inch , 5 blade on order for my R25! Thanks @Submariner !! I'm most worried about getting that cotter pin in. Not my favorite part of this process. Any tips are welcome.
@Submariner how do I get LemonDrop to give me docking lessons? I want flawless docking skills too.
Yesterday, I was able to get them built and installed with the help of the video posted by fellow Tug Nutter Martin.
Unfortunately, the first trial run was a quick trip. The 15 inch props had no where near the much needed stern lift that the current OFS5 props
have and the mid range results were much worse. I have attached a few pics below.
Some of the key comparisons:
3500 RPM: SCE: 19 MPH, .9 MPG vs. OFS5: 24 MPH .9 MPG
4000 RPM: SCE: 26 MPH, .9 MPG vs. OFS5: 30 MPh, .9 MPG
The one area of improvement was WOT where I could get up to 5800 RPM with SCE and 44 MPH vs. 5200 RPM with OFS5 and 42 MPH.
Hence, I’ll be removing the SCE and planning to keep the OFS5s, even with lower RPMs since I rarely ever travel at WOT.
While the results I read are very good for Ranger 25/27 single engine boats, these props do not have sufficient stern lift for Cutwater dual
engine boats.
The SCE Modified props came with barrel and flare extensions that I installed before testing, I don't have a side view picture of those props, but, I noted that I followed Martin's video installation instructions. The OFS props are standard and do not have extensions.Did your props not come with the barrel extender?
The SCE Modified props came with barrel and flare extensions that I installed before testing, I don't have a side view picture of those props, but, I noted that I followed Martin's video installation instructions. The OFS props are standard and do not have extensions.
Crossed my mind...are you thinking the extension/flares that I already have or a different one for the OFS Props?They can put the exhaust tube extensions onto the OFS props. Just as an FYI.
Crossed my mind...are you thinking the extension/flares that I already have or a different one for the OFS Props?
BTW, I've changed props so many times, I forgot...the SS2 props used: thrust washer->prop->->spacer->flat washer->crown nut/cotter pin. For PowerTech, I think it's no spacer, but, keep the flat washer, crown nut/cotter pin as the Cushion Lock replaces the spacer. Do I have that right?
OK, I'm not sure how motivated PowerTech is to continue trials and I'm getting a little haggard after spending years on the Sharrow trail;-)The exhaust tube(s) fit the OFS and SCE prop's. I have an OFS4 that'll accept the exhaust tube off the SCE5. But the prop has to be machined by PowerTech to accept the exhaust tubes. You could reach out to Jared at PowerTech and see about sending your OFS5's back to them to have them modified to accept the exhaust tubes.
I've never had a spacer on the F300 with the R27. The SS2 3 blade, OFS4, SCE5... all were Thrust Washer -> Prop -> Flat Washer -> Castle Nut/Cotter Pin.
Unfortunately, the first trial run was a quick trip. The 15 inch props had no where near the much needed stern lift that the current OFS5 props
have and the mid range results were much worse. I have attached a few pics below.
Some of the key comparisons:
3500 RPM: SCE: 19 MPH, .9 MPG vs. OFS5: 24 MPH .9 MPG
4000 RPM: SCE: 26 MPH, .9 MPG vs. OFS5: 30 MPh, .9 MPG
The one area of improvement was WOT where I could get up to 5800 RPM with SCE and 44 MPH vs. 5200 RPM with OFS5 and 42 MPH.
Hence, I’ll be removing the SCE and planning to keep the OFS5s, even with lower RPMs since I rarely ever travel at WOT.
OK, I'm not sure how motivated PowerTech is to continue trials and I'm getting a little haggard after spending years on the Sharrow trail;-)
Thanks. My (FM installed) SS2s on F300s both have spacers, I pulled them out earlier for the Sharrows. The config. looking like this:
OFS - 5 BLADEWhat pitch are you running on the OFS5? Being able to only get to 5200 RPM at WOT will most likely result in excess carbon build up over time on the engine since you won't be able to run the boat hard enough to blow it out. The Yamaha tech who gives the presentation at the Fluid Motion September Rendezvous in Roche Harbor has said several times, that the service manual states "5000-6000 rpm at WOT", but realistically, 5500-6000 RPM is where you want to be.
My boat came with the identical SS2s on a 2019 Cutwater C302c LE (heavy generator aft).The factory prop's on a C32
Cutwater C-32 Sedan - Twin F300’s - Saltwater Series II - 19-TL, 15.25
Cutwater C-32 Command Bridge - Twin F300’s - Saltwater Series II - 19-TL, 15.25
19 pitch is standard.
I'll look at the calculator, but, expect I'll confirm what I already know. The OFSs are best for hole shot, plane, mid range speed/efficiency and poor for top end.On the R27 with the F300, the SWS2 3 blade, OFS4, and SCE5, all were 15 pitch. The only change is the number of blades and diameter of the prop.
One of the tools I used for prop testing was Mercury Racing's prop slip calculator.
Yamaha's have a 1.75 gear ratio (for the calculator).
My results yielded the following:
SWSII 3 blade, 15 pitch, 15.75" - Prop slip: 15
OFS4, 15 pitch, 15.25" - Prop slip: 23
SCE5, 15 pitch, 14.00" - Prop slip: 19
Ideally, the prop slip should be 20 or less.
Prop Slip Calculator | Mercury Racing
Quickly determine slip for Mercury Racing propellers using our prop slip calculator.www.mercuryracing.com
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