Propeller Performance

Halilogger

Halilogger

Active Member
Thought I'd start a thread on propellers, I figured it could help any of us boost performance and economy. I'll list what I think is important information, without getting to technical, if I miss anything throw it in. Boat weight will be loaded weight, three adults. Hull design, horse power, propeller metal type, pitch,and diameter. If you made a change on your prop, list the positive and negatives.





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Weight 5600lbs
Drive Outboard
Moderate deep V
225hp 4 stroke
Aluminum prop
pitch 21
Diameter ?

I went from a 19 to a 21 pitch and gained 3mph which increased my economy and reduced my wear and tare. I'm slightly slower out of the hole, but I'm sure most of you will agree our hole shot isn't that important as long as your not plowing for a quarter mile.
I've always liked stainless, but because of cost I went with aluminum. I was very impressed with the Turning point props,they had exhaust ports, good cupping, more rake, and excellent price $140

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The higher pitch will put MORE wear and tear on the internals. You are now one gear higher out of the hole. Same as starting off in 2nd gear in a car instead of 1st. With a heavily loaded boat on plane it will be like going up a grade in 5th when you should shift down to 4th. Your top end speed will be up, rpms down and engine life down as well. Wear will show up on wrist pins/rods. (piston drop) I never worry about top speed, instead I want the optimal gear at my normal cruising speed.
 
X2:Dprofisher.

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More pitch = cruising less rpm less wear and tear on the motor, we are not talking extreme changes as long as you can get 5200 to 5800 rpm when making a pitch or blade change. If you run at max weights you may have to pitch down if you run at lighter weights like me you can pitch up and extend the life of a motor. When they first came out with over drive gear vehicles you think this was more wear and tear.
I do a lot of cruising into logging camps, my motor does not lug at all when doing so, that's why most people carry different pitch props for different applications.
Also when you make prop changes like going to stainless, you can increase your pitch because the blade thickness is thinner so it cuts through the water easier, exhaust ports can reduce ventalation, more cupping can be more efficient.
This is why I started this thread because if you think the factory prop or putting a stainless on with the same pitch gives you optimal performance you wrong. There are so many different hull designs boat designs, your factory prop will give you middle of the road performance. They have no idea if you will be loading your boat up or running dry weights.

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Halilogger you are on the right track just keep a close eye on the RPMS sometimes it is easy to get on the wrong side of optimum.:D

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Halilogger, stainless props of the same pitch are harder on the engine, they don't flex like an aluminum will. An aluminum when flexing is less efficient (slips) allowing rpms up a bit without all the bite..similar to a clutch = less strain and slower coming out of the hole. Also the stainless is much heavier and thus takes more hp to swing. I would never use an aluminum as there is way to much small stuff in the salt around here and they would be in the shop all the time getting straightened. Your comment about overdrive...is true with cars because the you have a transmission that compensates for load and changes in the road. Your boat has 1 gear. Forget about "performance" that sounds too much like what will she do wide open...who cares. Engine life is maximized by having your engine loafing along at the rpm you run at 95% of the time...for me that is 42-4400 rpms and 30 mph. A engine running lower rpms but working harder at those rpms will wear out faster than one running more rpms but with less strain on the moving parts. My engine is supposed to top out at 5400 wide open, with the prop I have on it my top rpm is probably around 5800...I never taken it past 5400 and it has only seen that number once or twice.
 
Your missing my point, two identical boats 1 runs with light weights all the time, the other with a thousand pounds, the lighter boat can pitch up and put no more strain on his motor than the boat that runs with heavy weights all the time. Every thing I've said here has many variables I can't account for them all, but you seem to have tunnel vision.
I to use to think stainless was the cream of the crop,it's not, there are a lot of advantages with aluminum. For the record I'm not saying there better, but weigh out the positives and draw your own conclusions.80% cheaper to buy 60% cheaper to repair and equal to and some people say better performance.
I run over a thousand miles a month, with the recent heavy rains, Toba Inlet was filled with debris worst I"ve seen, you can't help hit chunks, not a single chip in my prop. Docking at Cleagh Cr in Quatsino I hit a 1" cable under the water, took a nice chunk out of my prop, inch and a quarter wide 1 inch deep, $ 40 bucks to fix I would hate to speculate what would have happend to a stainless prop and cost to repair.

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I'm missing something here. I enquired about repowering my Orca-going to a 300 yamaha (suzuki) from a 225 yamaha. The saleman asked what prop I had and I told him a ss 15-M. He said that would work out fine. It seems to work on the 225 allowing a top 5600 rpm- I thought I would have to increase pitch or diameter to handle the extra 75 HP. I have done the calculations on the merc site and they sort of agree with the salesman possibly increasing the pitch a little to 15.8. Increases top speed by 5 knots-more interested in the lower rpm at cruise. My question is-if the 225 is swinging the 15-M prop at 4200 rpm and the 300 HP is swinging the same prop at 4200 rpm aren't the speeds going to be the same-How does that make me farther ahead.

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"So many fish-So little Time"
 
How many people run their boats with identical loads all the time? Can you realistically change a prop every time you increase or decrease you load? My charter vessel runs with 1 to 5 people on board, never the same. Sometimes 4 big burly guys, sometimes 3 small kids. I prop the engine for the heavier load and leave it alone. My top speed may be 2 to 3 miles an hour less at WOT. It still does over 40 mph wide open and cruises at 30. Its a 22 Seasport with a 1997 200 Yamaha 2 stroke. It is a carbed model with the original powerhead and leg on it. It has been rebuilt once and has just finished its 2nd season since being redone. I've run a stainless prop since 1989 on my present boat and one before. I have spent $00.00 on prop repairs since 1989. I can't say that about the aluminum ones I had before. In fact my high thrust 9.9 hit a chunk of wood this summer and one blade needs attention. To each his own, but my formula has saved me down time and grief over my 35 years of boating. So has proper maintenance.
 
The 300 won't be working as hard as the 225 with the same prop. The gear cases will also have different gearing ratio's which I'm sure will be slightly higher on the 300. Ask the shop to let you try some used props of different pitches to get it where you want it.
 
Profisher's definately right on this, as pretty much always:)

Remember there is a horsepower curve, and like PF says, aluminum props actually decrease in pitch under load where sst does not. The cutting through the water between the two makes no difference.
This is especially significant during hole shots or powering out of a following sea, among other things.

Propping is an art in itself and I would recommend consulting a reputable prop shop for a final opinion.

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Fill the dam tub!
 
IFL the thickness of the propeller blade does matter it's called friction, thicker blade more friction.
First of all I'm sure your proped correctly, I never said you were not. Your mixing words up, I never talked about gaining performance at WOT, who cares about WOT. I'm sure every boat owner on this forum doesn't run his boat at those RPMS, and I never said exact weights. It was your theory about additional strain with more pitch, every time you put 4 burly guys in your boat you put strain on as you say the internals. Which is some of the points I made at the beginning of this thread, If I ran with the weights you do, I would be running 19, It's me and my work gear 300lbs some times 1 other person, so because I run with lighter weights I bumpt up to 21 gained 3 mph at 4400rpm not WOT.I also reduced fuel consumption wear and tear on the motor through less travel time and my motor is not Lugging at all.


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Hey springfever check out Turning Point Props website there legacy aluminum won't cost you a grand if you do upgrade your motor. Also what your confused about rings true, a friend of mine has 22' Daigle he had a 150 Yamaha, He upgraded to 250 Yamaha, and hes not happy burns 3-5 gallons more an hour and only gained 2mph.

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Going by your posted specs my boat is lighter than yours and I'm running a 17". With a full load of fuel I'm at 5000 pounds. With 3 heavy weight guys (at 200 pounds each) I match your unit. So your light load is my heavy load and yet 4" difference in pitch.
 
OMG!!! Do like to argue I'm a 225hp 4 stroke EFI, your a 200hp carbed 2 stroke, your hull design is way different than mine, and I'm running a aluminum prop.Other than the weights I'd say everything else is different. There is not just 2 or 3 things to consider when selecting a prop. Even those prop selectors where they ask you 8 different question don't account for all the variables. Most places that sell props tell you to try 2 or 3 different props.
All I was trying do was bring to light, mostly to the newer boat owners, prop selection plays a very big part of boat performance. A lot of guys on this forum have been running boats 20+ years, and I'm sure there prop selection for there usage is bang on.

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That is also my way of thinking but I am having trouble locating the right props and find the choices are limited for counter-rotating props. I am a fan of stainless props but if you find what suits you in aluminum,more power to you at a better price.:D:D

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Ok OMG back at ya :D As you know a 4 stroke fires (power stroke) every 2 revolutions and a 2 stroke every revolution. Which one do you think lugs more if both are set up with the same props? Just chatted with my buddy who is a long time Yami dealer mechanic here in Victoria. They never use 21" pitch props on boats of our size and weight. He says they have 21" props hanging all over the walls in the shop because they don't use them. 19" is as big as they go. The following are his words not mine. Your engine should run 6000 rpms WOT with your standard load and set up. The new 4 strokes prefer to run at higher revs than the older 2 strokes. 4800-5000 is desirable at cruise. They are a double overhead cam engine and like more rpms and less load. His words too are....he is fooling himself if he thinks running 4400 is saving the engine, the opposite is true.
My engine tops out at 5400-5500 and I run it at 4200 to 4400, just a little more than 1000 rpms off WOT. Your engines WOT should be 6000 and if you run it the same it should fall around 4800 at cruise. PS Not trying to be argumentative...just trying to help you get what you want...longer engine life.
 
Ok OMG back at ya :D As you know a 4 stroke fires (power stroke) every 2 revolutions and a 2 stroke every revolution. Which one do you think lugs more if both are set up with the same props? Just chatted with my buddy who is a long time Yami dealer mechanic here in Victoria. They never use 21" pitch props on boats of our size and weight. He says they have 21" props hanging all over the walls in the shop because they don't use them. 19" is as big as they go. The following are his words not mine. Your engine should run 6000 rpms WOT with your standard load and set up. The new 4 strokes prefer to run at higher revs than the older 2 strokes. 4800-5000 is desirable at cruise. They are a double overhead cam engine and like more rpms and less load. His words too are....he is fooling himself if he thinks running 4400 is saving the engine, the opposite is true.
My engine tops out at 5400-5500 and I run it at 4200 to 4400, just a little more than 1000 rpms off WOT. Your engines WOT should be 6000 and if you run it the same it should fall around 4800 at cruise. PS Not trying to be argumentative...just trying to help you get what you want...longer engine life.
 
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