R27-OB Propeller Testing <-- RESULTS are IN!

[Robert]

I will be installing the OFS4 Modified on my R23 Monday. I'll try and get before and after performance data for the 3-blade and report back.

 

[Submariner]

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.

It's easy to get the pin in. I use a string to keep from dropping it. I updated our website with new photos that illustrate this, as well as what the prop looks like installed. I sent my Prototype back to PowerTech, they got the prototype off and I'm now sporting the finished/production prop with a 4" black anodized exhaust extension.

LetsGoChannelSurfing

www.letsgochannelsurfing.com

 

[Submariner]

@Submariner how do I get LemonDrop to give me docking lessons? I want flawless docking skills too.

I'll ask her if she gives lessons or has any advice. She may just suggest good insurance. Lol.

 

[Rocky Lou]

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.

 

[Submariner]

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.

Post a pic of the dual OFS5's. I'd like to see them. 🙂

 

[Rocky Lou]

Happy to oblige:

 

[RT25_LouLou]

Did your props not come with the barrel extender?

 

[Rocky Lou]

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.

 

[RT25_LouLou]

Thanks @Rocky Lou My bad for not paying close enough attention. I was on my phone and its a touch harder on the phone.

 

[Submariner]

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.

They can put the exhaust tube extensions onto the OFS props. Just as an FYI.

 

[Rocky Lou]

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?

 

[Submariner]

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?

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.

 

[Rocky Lou]

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.

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:

 

[Submariner]

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.

What 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.

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.

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

 

[Submariner]

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:

Looking at that photo, I'd say the spacer is part of the cushion lok hub. When I swap prop's... the cushion lok hub stays in the prop.

 

[Rocky Lou]

What 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.

OFS - 5 BLADE
15.25" DIAMETER
17 Pitch
Agree, the RPM issue is what I have been trying to solve. I'm reasonably satisfied now as I'm performing generally like boats of similar size and weight.

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.

My boat came with the identical SS2s on a 2019 Cutwater C302c LE (heavy generator aft).

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

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.

It may have been a better idea for me to try the OFS5 15 pitch.

 

[Submariner]

It's been awhile since I posted updated stats.

I am loving the SCE5 Modified, Channel Surfing edition, with the full 4 inch extension.

Everett to Bremerton
In mid February we went from Everett to Bremerton for the Bremerton Yacht Club Heavy Weather Cruise.
Average fuel efficiency for round-trip: 1.74 mpg. (92 miles)

Everett to Bremerton - 46 miles, 2 hours 21 minutes. 27.8 gallons of fuel. (Dock to Dock, 1.65mpg)
Bremerton to Everett - 46 miles, 1 hour 50 minutes. 25 gallons of fuel. (Dock to Dock, 1.84mpg).

We didn't have bad seas, but we also didn't have great seas. Just an average day in the Pacific Northwest, in February.

Everett to Port Orchard
In March (last weekend) we went from Everett to Port Orchard with the Roche Harbor Yacht Club for their St. Patty's day cruise.
Nearly the identical trip as Bremerton was last month. Port Orchard and Bremerton are right across the waterway from each other.
91.4 miles on 52.4 gallons of gas. (1.74 mpg averaged, round trip).

Seas weren’t bad coming home Sunday, but was a little choppy. I cut across the tide and wind, perpendicular as I crossed Puget Sound on our way home, slowed down to 15mph, at 8.6 gph (1.7mpg). Once across Puget Sound, I then changed direction, headed north, traveling with the wind and tide on the stern, I sped up to 28mph at 16.1gph (1.7mpg). This is what I love about this prop and exhaust tube setup.

Summary
I switched to using Argo for my navigation and trip planning on my phone and tablet while at home on the couch. I set it to use 28mph and 17.5gph for all my trip planning. Dials in my timing and fuel consumption pretty darn close. 🙂

In the photo, I'm doing 15mph at 8.6gph = 1.7mpg. Disregard the engine trim indicator. Assume it to be 3 bars. (my engine trim sensor needs to be replaced).
As I turned to head north, I increased speed to 28mph at 16.1gph = 1.7mpg.

 

[Rocky Lou]

Jared is sending out another set of OFS5 16 pitch to use with my existing extensions as I return the SCE5s.I didn't want to return the OFS5-17s and wait for them to be modified. I will start a new thread for Cutwater boats since the problem is solved for Ranger 25/27, but, not for CWs.

 

[Submariner]

A friend of mine is taking delivery of his R27-OB today (as I type this). He's got a '23 model, NW edition R27. Used boat, new to him. Boat was a trade-in, so he's going through the 2-day factory delivery. Because the boat was just sold to him, and he's taking delivery, the boat is empty. All my testing on Channel Surfing was done with our stuff on it, as I was focused on what I could realistically expect to see at the fuel dock.

He put on an SCE5 Modified, Channel Surfing edition prop and sent me the following info.

Wide open throttle: 39mph, 5600 RPM, 27.1gph (1.43mpg).

The Mercury Racing slip calculator puts this at 14% slip. (anything less than 20 is good).
Not bad... 😎

 

[Submariner]

A friend of mine with his brand new 2025 R27-OB LE, with the dinghy lift and less than 20 hours on the engine... SCE5 Modified, Channel Surfing edition. He ran the boat from Everett to Oak Harbor yesterday. Wasn't great weather, but wasn't bad. What you might expect for March in the Pacific Northwest. He txted me a photo of his dashboard/chartplotter. 62.3 miles on 36.0 gallons of gas. 1.73mpg averaged for the trip. He rode mostly at 30mph. His exhaust tube didn't fall off this time. 😀

We used a lot of loctite, and let the prop sit out of the water for several days to ensure the loctite had time to set.
Also, I swapped out his prop by simply backing the boat into the dock as pictured.