Four Blade Results

Seemed like a good place to post this:

Results for Stainless Quicksilver Silverado 3 blade 13 3/8 R 14 pitch prop on carbonated Honda 90; same trip calm water.
I almost turned around 2 minutes out of Whittier because I could tell right away this prop wasn’t going to work, but the crew said no-way. I waited tell we reached our night anchorage before pulling down the dink and changing out the prop, took like 10 minutes.

Quicksilver-Not good! It was like driving a car with a 4 speed stuck in 3rd gear.
4200 rpm – 12 mph
4800 rpm – 15 mph
5500 rpm – 20 mph
6000 rpm – 22.5 mph (WOT)

Same trip putting back on my stock 3 blade 15 pitch prop.
4200 rpm – 17.5 mph
4800 rpm – 20 mph
5200 rpm – 25 mph
5500 rpm – 27.5 mph (WOT)

Granted I can’t achieve 6000 rpm with the old prop but way better performance at lower RPM. During sea trials with wife and child and a half tank of gas I was able to make 34 mph at 5850 rpm.

At this point I don’t think there is a better all around prop then stock aluminum 3 blade that came with the boat.

Stainless Quicksilver goes back to WM for store credit.
 
Certainly interesting--I wonder if for some reason the SS prop was mis labled? I don't know the blade area and diameter of the stock prop. The aluminum should flex some. Of course there are lots of differences between props--cup, rake, etc. The best way to check out props is to work with someone who will allow you to try different props. Folks like "prop gods" usually will get the prop right, but not they will exchange until you do. I have run many of my boats with stock props--and they work great--others need a custom prop. My Caracal was used, and came with what is thought to be the best prop--but its numbers are not what I expect....similar to your SS.
 
starcrafttom":1viuuaxe said:
wow, big difference. especially between 4850 and 5200 rpm, where you will run the most. with your stock prop how is your fuel burn?
Click to expand...

My overall MPG is about 3.3 to 3.5 for a typical weekend. Don’t have a flow meter just fill up the boat after each trip and divide into GPS mileage.. I usually cruise at 20 mph but push it up to 25 on returning to port the last 10 or 15 miles-sure that doesn’t help with fuel economy. We just never have the time or patience for relaxed cruising on 2 or 3 day weekends, perhaps someday.
 
Jay,

On the fuel injected 90 I found the Quicksilver 14 pitch to be the best all round prop and was able to get 31 mph plus with a heavy boat and good fuel economy on the low end. It almost sounds like the prop was cavitating. Are you running a Permatrim?

Last week end I ran a 4 blade Solas 15 pitch stainless on my Yamaha 150. I noticed a little more vibration with it, but it did perform well with a WOT speed that hit 35 mph just when the boat started porpoising. Fuel economy was slightly better than the 4 blade aluminum Solas in the same pitch. Fuel economy went up with speed. In other words 24 mph was better than 20 and 30 was better than 24. It peaked at 2.9 mpg at 30 mph. Just can't find any water to go that fast very often.
 
Earlier in this thread Marc from Wefings wrote……
“……There is no new mousetrap in the world of props and the available ones are there for a reason . Get one to turn [with a load] fairly close to where your motor's RPM range should be and you have a winner .”

I have recently tried, what is generally reported here to be, the optimum prop for the boat. It is a 3X13.5X15 on my BF75 Honda pushing a 22 Cruiser with a medium load and, so far, I really like the increased speed at lower RPM compared to what I have been running (4X13X14). I think it must be giving me better MPG’s as well.
Honda Marine’s Propeller Test Report also recommends the 3X13.5X15 for the BF75/22Cruiser combo. Their tests return a W.O.T. of 5500 R.P.M. which is right in the middle of where W.O.T. should be for this motor (5000-6000).

My question to Marc and the Brats in general is this…My W.O.T. results are just barely 5000 R.P.M. (that’s “fairly close”). Is this acceptable given that it just makes the minimum W.O.T. or should I have it re-pitched to 14 to allow for the heavier loads? If I were to re-pitch, what do you folks think the end result will be?
As a footnote…I also have tried a 4X13X15 and it gave me barely 5100 or 5200 RPM at WOT so I had it re-pitched to 14 and it now delivers 5500 RPM at WOT but my cruise speed is really reduced (15 NMPH at 4800 RPM).

Thanks, Cheers, :beer
Tom
 
Tom on Icarus":2g6qm95c said:
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Their tests return a W.O.T. of 5500 R.P.M. which is right in the middle of where W.O.T. should be for this motor (5000-6000).

My question to Marc and the Brats in general is this…My W.O.T. results are just barely 5000 R.P.M. (that’s “fairly close”). Is this acceptable given that it just makes the minimum W.O.T. or should I have it re-pitched to 14 to allow for the heavier loads? If I were to re-pitch, what do you folks think the end result will be?
Thanks, Cheers, :beer
Tom
Click to expand...

I'm no expert and I have a different hull (Venture 23) and different engines (twin Yamaha 50's), but I've been told you should shoot for the upper half of the WOT range with whatever you consider a normal load. I do some long-range cruising with a very heavy load and recently went to a lower pitch to achieve that goal. I'm quite happy with the results. It does mean, however, that WOT with a light load now can hit the WOT max of 6K if conditions are just right. Of course I don't run like that very often - mostly just out of curiousity once in a while.

Predictably, I'm turning the new props a little faster than the old ones at any given speed, but performance and mileage appear to be at least as good as before.

Honda guys may know better about optimum WOT targets for your motor.
 
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