Spare prop for R27 with 300 Yamaha

Mike and Sarah

Mike and Sarah

Reel Salty Bliss
Joined
Feb 21, 2020
Messages
281
Fluid Motion Model
S-310 SC
Non-Fluid Motion Model
2013 Alumaweld Stryker
Vessel Name
Reel Salty Bliss
I won a new propeller on a charity auction. The propeller brand is Power Tech. I mainly will use it as a spare but am hoping for similar performance especially fuel economy at cruising
My current propeller is a Yamaha saltwater series 2. 15 3/4 diameter and 15 pitch.
I am happy with my performance all around.
Power tech shipped me a 15.25 diameter 15 pitch prop. 3 blade like the Yamaha
So here is the comparison
Yamaha ———————-Power tech
5700 Max rpm 6000
39.5 mph. Top speed 31 mph
1.95 mpg. Cruising 28 mph. 1.58 mpg
3.0 mpg. Slow cruise 8 mph. 2.3 mpg

So the power tech prop is a 1/2 inch smaller diameter and same pitch. Why so much difference in top speed. I can see a little loss if fuel economy but mount as much as what I got. I went with power techs recommendation but I really need to get something different. Would a 17 pitch make up for the smaller diameter?

I know there is a bunch of opinions out there. Ha Please educate me.

Mike
Salty Bliss
2020 R27 300 Yamaha
 
There is more going on between the two propeller differences than 1/2" of diameter. But that half inch could be causing some of the slip along with some less cup. The numbers you posted in prop performances shows a difference of 20 percent more slip (Power Tech) compared to the (Yamaha prop). The PowerTech is performing with approximately 36 percent slip and the Yamaha is approximately 16 percent slip. The best way to decease slip is increased diameter and cup.

If I was looking for a spare prop I would Call Power Tech , talk to a representative. Tell him /her what you are running now give him/her your numbers speed/rpm. Ask for a comparable prop or one that will give you better performance. I would personally be looking into a 4 blade for better midrange performance and better stern lifting. Just my opinion.
 
Yamaha M/T Series Offshore I Stainless Steel Propeller - 4 Blade - 14.50 Dia - 15 Pitch - RH Rotation - MAR-14415-0R-E0

Had to buy a hub too. It’s not perfect. But worked to keep the boat on plane.

Probably lost top end but never go WOT anyway.

Perhaps they could make you one similar.
 
Brian 27 OB":3iyikbgq said:
Yamaha M/T Series Offshore I Stainless Steel Propeller - 4 Blade - 14.50 Dia - 15 Pitch - RH Rotation - MAR-14415-0R-E0

Had to buy a hub too. It’s not perfect. But worked to keep the boat on plane.

Probably lost top end but never go WOT anyway.

Perhaps they could make you one similar.
Click to expand...

What is your wot rpm? Thanks
 
It’s on the trailer now. Will let you know when we get to Florida in January. If I remember.
 
I replaced my 3 blade with the same 4 blade as above. I might have lost 2 mph at WOT, but I rarely do that at a 25 GPH cost!
I get up on plane faster and have much improved reverse performance.

Works for me.
 
My WOT RPM dropped a bit, down to 5800
 
Propeller update.
It took a while to get the exchange propeller. I had the boat on the hard this week to change lower unit lube and zincs.
So here are the performances results.
Slow cruise 8 mph - 3 mpg. @ 1600 rpm
13 mph - 1.89 mpg @ 2900. This is a big improvement in economy and allows to good control in really rough conditions
Off plane 14.6 - 1.71 mpg @ 3500 rpm
On plane slowed down for rough conditions 24.4 - 2.0 mpg @ 4000 rpm Boat stays on plane at this speed unlike the stock 3 blade
Top speed 37.5 mph - 1.36 mpg @ 5500 rpm this is a 250 rpm lower than the stock 3 blade

Pictures of speeds and rpm in album.
 
I wish I had this propeller from the beginning. Really like the performance improvement.

We are moving up to a R-31 CB in June. I will pull the propeller off then and have it for sale.

We love our r27 but decided we would move up sooner than later. We will still do fishing, shrimping and crabbing out of the 31. Now we just have to get used to a slower cruise speed.
 
Hi Mike, thanks for this very informative post. You're midrange numbers are much better than what I get on my Suzuki 300 with the original prop. I don't see the spec on the 4-blade you actually installed. Do you happen to remember?

Thanks
 
Mike&Sarah. I’m confused, which prop are you giving the improved numbers for. Your improvement is significant

Perry


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brofish17":3gdhe9w6 said:
Hi Mike, thanks for this very informative post. You're midrange numbers are much better than what I get on my Suzuki 300 with the original prop. I don't see the spec on the 4-blade you actually installed. Do you happen to remember?

Thanks
Click to expand...
I have that 4 blade prop that Mike used to have when he had his R27. It’s on loan to me from Bob who purchased it from Mike. (A special thanks to Bob!).

I spent this past holiday weekend running it through its paces. I’ve got some numbers to crunch in a spreadsheet and will post all my data here later this week.

I’ll most likely have 2 sets of data. We were really heavy this week. 5 adults, 3 dogs, 4 crab pots, plus the dinghy, and all the gear that goes with this. We are offloading everything now and will hit a slack high tide this week to run some tests again with a lot less weight as I want to specifically compare it against the Yamaha 3 blade prop for which I already had detailed data for.

But it’s safe to say, with as much weight as we had this week, this will yield worse case scenario. 🙂


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Thanks Martin, looking forward to the numbers in both cases. Always looking for a way to improve the fuel burn rate.


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This is the comparison against the 3 blade Yamaha factory prop vs a 4 blade PowerTech prop on a R27-OB with the Yamaha F300.

The data is below for your review.

Yamaha Saltwater Series II, Stainless Steel, 3-blade. 15.75", 15pitch (Summary Data)
http://www.tugnuts.com/gallery2.php?g2_itemId=80243

PowerTech E-Series, 4-Blade Stainless Steel prop picture
http://www.tugnuts.com/gallery2.php?g2_itemId=80252

PowerTech E-Series, Stainless Steel, 4-blade. 15.25", 15pitch (Summary Data)
http://www.tugnuts.com/gallery2.php?g2_itemId=80246

PowerTech E-Series, Stainless Steel, 4-blade. 15.25", 15pitch (FULL Data)
http://www.tugnuts.com/gallery2.php?g2_itemId=80249

Obviously, there's a lot of subjectivity to tests like this. When I tested the 3 blade I had flat seas and I did not have the Lenco Autoglide. When I tested the 4 blade the seas were calm as it was slack high tide, but not flat and I had the Lenco Autoglide. So it's likely that these numbers would improve on absolute flat seas. (The Lenco Autoglide will likely improve fuel efficiency).

Based on what I've seen, I do think this particular PowerTech prop is sized perfect for the R27-OB.

Personally, I like the 4 blade prop as it feels more balanced and smooth. It gives better control and more thrust in reverse. I am able to stay on plane at slower speeds which gives me a wider band of speeds to operate between. I only lost about 3 knots of top end speed (down to 33knots at WOT). The Yamaha F300 hits it max horsepower rating at 5500 RPM, and the 4 blade hits WOT at 5600RPM.

If you're looking to save on mpg, I don't think there's enough of a difference here to matter. Review the data closely and compare to your usage. I think the difference amounts more to personal preference.

I'm going to go order myself one for the following reasons:
1) I want a spare prop as I will eventually ding the prop I have. (It happens, just a matter of 'when').
2) We often run heavier, and having the extra blade helps with stern lift.
3) The 4 blade provides a wider band of operating speeds up on plane at slower speeds.
4) Reverse thrust improvement.
5) Smoother/more balanced feel of the prop.
6) The cushion hub of the PowerTech 4 blade prop is softer/less clunky than that of the Yamaha 3 blade.
7) Better grip at slower speeds, which amounts to more control while slowboating or when in rougher seas.
 
Thank you for the effort you put into this. Excellent!


Sent from my iPhone using Tapatalk
 
Martin,

Thanks for the prompt work on this. It’s great info you have supplied. Have you looked at the cost of the new prop. The reason I ask is I currently have another three blade prop for a spare. It is not optimized for our boats. It came off my 22 Arima. Thinking I might sell it and get the prop you tested. When I look on the Yamaha prop selection web site they recommend a 15.75 with a 13 pitch for best fuel economy. To bad we don’t have away to try a few different props


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The prop selected for the R27-OB I know was done by Yamaha, specifically. They are the one's who put together the Yamaha spec sheet's posted at Ranger Tug dot com for the R23-OB and R27-OB, for Ranger Tugs.

Looking up the F300 engine schematics, Yamaha has the following prop's listed as options (all are 3-blade)
14 3/4 x 23pitch
15 x 21pitch
15 1/2 x 17pitch
15 1/4 x 19pitch
15 3/4 x 13pitch
15 3/4 x 15pitch <-- This is what comes with the R27-OB

Yamaha also lists these 4 blade props as options:
15" x 21 pitch
15" x 22 pitch
15" x 23 pitch

Note: These are all prop's listed that match the motor, not necessarily the boat.
Prop selection is very much an effort of "best guesstimate" then go do sea-trials to see what happens.

Cost wise, the Yamaha 3 blade is actually a little more expensive than the Power Tech. But they are comparable in cost.
 
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