small holes drilled in prop

[hugh hargett]

Rodney,I have no idea what Andy has in his box thats youre assumption, does anyone?I dont even know if he in fact has a SWPG do you? Rodney if you find a way to accurately take LE numbers with your style guage please let me know as Im just curious want to know how you do it with that gauge. Do you agree that its important to know where it begins and where it ends? Or are you only and should one be only interested in TE numbers??Lets stay on track....Did you goto Jims boat dock and check out the article????

 

[RodneyPierce]

No, I havnt gotten over there to read it yet. I dont know what he uses either, but thought that I had read somewhere back in the archives a post of him speaking highly of the woods gauge. I would have to go back through and dig around for a while.

 

[RodneyPierce]

And, I really havnt gotten that far in my "prop knowledge" to be able to tell what significance the LE pitch makes. Ive only concentrated on the TE pitch/cup. So thats really all I can comment on. And I JUST started messing with that to be honest. Like I said in the PM, Im no prop pro, heck Im below amateur at this stage. But, where there is a will to learn, there is a way to learn. And Im working on it.

I do have props from MS, Aaron Alberico, Mike Larson has done a couple for me, Ive even messed around with a few others props. I can say, the people who are "professional" if you will have significant gain over what my own props do. They launch easier, and they pull more speed. SO, I havnt figured out where Im going wrong yet, but give me some more time, and I will.

 

[hugh hargett]

All those men do great work Im sure but here again this isnt a whos the best prop guy thread. All im doing here is asking how to get all the numbers from that style guage accurately. It should start to be clear to you at somepoint thats its not as simple as taking TE numbers eh? Just try it yourself dont debate me you have the gauge right there in your hands and you have several people to call and ask, you just named them. So get back at IW with the answers you get. Agreed?

 

[RodneyPierce]

Ill give it a shot and report back.

And your right, there isnt a single post above FROM ME saying one guy is better then the next....

 

[hugh hargett]

Waiting for answers and if you dont get any clear ones you can have this thread Rod , but remember the numbers and how a little variance can affect the props speed by several mph.Also check out jims boat dock. Its some dang good info there.

Happy Boating

Hugh

 

[anthony_marquart]

I think what you may be looking for is the pitch progression.. I think most props are of a progressive pitch design,. meaning that the pitch increases from the leading section to the trailing section.

 

[Jim Allen]

To clear up on what Andy Brown thought or did concerning props, the following is taken from a direct quote that appeared May 27, 2003, 6:32 pm, post #230 on intlwaters.com.

"Leading edge pitch is everything. The first 1/3 of the blade will determine the potential speed of the prop. The last 2/3 must have a certain amount of progression to maintain water/blade contact. 60-70% progression seems to be enough for most high drag boats. 30-40% for most low drag boats. Like everything else, it becomes a trade off between blade area & progression. In my book, true pitch is the leading edge pitch only. The leading edge is the only part of the prop that is making contact with still (non-moving) water."

post #199

"The progressing pitch after the leading edge is needed to keep water in contact with the blade. This is dependant on the drag of the boat. High drag= high progression. Low drag= low progression. Forget slip. How fast do you want to go? Leading edge pitch - 4.0" X 30,000 rpm / 1057 = 113.5 mph. The 1057 just converts inches and rpm into mph. No fudge factor. That's it. No slip Factor."

Does anyone think that a "pitch gage" which cannot measure the leading edge pitch accurately is worth?????

Jim Allen

 

[RodneyPierce]

Jim, thanks for digging back through to find that little tidbit there.

I am confident that one can measure leading edge pitch with nearly any gauge... Ill give it a try later.

 

[anthony_marquart]

Boy,.. doesn't that just though all our speed / cup calculations out the window!!! makes sense though..

To clear up on what Andy Brown thought or did concerning props, the following is taken from a direct quote that appeared May 27, 2003, 6:32 pm, post #230 on intlwaters.com.

"Leading edge pitch is everything. The first 1/3 of the blade will determine the potential speed of the prop. The last 2/3 must have a certain amount of progression to maintain water/blade contact. 60-70% progression seems to be enough for most high drag boats. 30-40% for most low drag boats. Like everything else, it becomes a trade off between blade area & progression. In my book, true pitch is the leading edge pitch only. The leading edge is the only part of the prop that is making contact with still (non-moving) water."

post #199

"The progressing pitch after the leading edge is needed to keep water in contact with the blade. This is dependant on the drag of the boat. High drag= high progression. Low drag= low progression. Forget slip. How fast do you want to go? Leading edge pitch - 4.0" X 30,000 rpm / 1057 = 113.5 mph. The 1057 just converts inches and rpm into mph. No fudge factor. That's it. No slip Factor."

Does anyone think that a "pitch gage" which cannot measure the leading edge pitch accurately is worth?????

Jim Allen

 

[Jim Allen]

Which speed cup calculations are you refering to Anthony? Could you explain?

 

[RodneyPierce]

.....delete.....

 

[anthony_marquart]

I guess it was more my own figures when trying to predict speed based on RPM.. and using cup (trailing edge pitch) numbers, which are much higher than the leading edge pitch numbers. Sounds like I was using the wrong numbers.

 

[RodneyPierce]

I guess it was more my own figures when trying to predict speed based on RPM.. and using cup (trailing edge pitch) numbers, which are much higher than the leading edge pitch numbers. Sounds like I was using the wrong numbers.

.....only one school of thought.......there are many.......

 

[Jim Allen]

I guess it was more my own figures when trying to predict speed based on RPM.. and using cup (trailing edge pitch) numbers, which are much higher than the leading edge pitch numbers. Sounds like I was using the wrong numbers.

.....only one school of thought.......there are many.......

This is very true Rodney. Some people are looking at the propellers tip speed to determine how much pitch & what diameter needs to be used.

 

[RodneyPierce]

Jim very true, and like said earlier, Im no prop expert, Im even below amateur status to be honest. haha. BUT, trying to pick up tid bits here and there and learn. Ive learned quite a bit by taking advise, applying it and trying it for myself. Gets spendy at times, but one cant beat hands on experience.

 

[hugh hargett]

Sometimes to learn you have to be able to seperate friends and alliances from the truth!When and if you can debunk theory that has been proven through mathematics and physics you dont get a boater of the year award you get a NOBEL PEACE PRIZE.Ill keep my eyes open for those LE numbers Rodney let me know how it all works out.

....... back to building boats. Thanks Dan for the endulgement.

later!

HH

 

[anthony_marquart]

thanks Confucius

 

[hugh hargett]

LOL :lol: I was thinking more along the lines on CON-FU-SION! LOL :lol: :lol: . Ill pay you back for that one when I make it up to concord.What Confucius say confusius DO! LOL. later Ant.

 

[Andy Brown]

No, I havnt gotten over there to read it yet. I dont know what he uses either, but thought that I had read somewhere back in the archives a post of him speaking highly of the woods gauge. I would have to go back through and dig around for a while.

Yep! I use the ORIGINAL Steve Woods/Andy Brown/ Ed Huhgey designed pitch gage which Steve built back in about 1999. Steve's newest gage is nice, but I am partial to the original unit.