prop grinding

[imported_bjs]

this question is for all the prop expert's i seen an article about sanding the prop.at the bottom were the blades start just above the hub of the prop by taking off 1/2 inch or more worth 200 to 300 rpm's.i was just wondering if this really works? has anybody ever done this

 

[Bondo]

Re: prop grinding

Any time that Blade Area is removed,..... More slippage will be the results,.....

I'm Sure that what you say is True,.....
The Question will be,....
Does it Help in Your situation,..??......

And,...... Are You going to be able to do this,+ have the Blades Balanced,+ Equal when your Done,..??.....

 

[Salmonseeker]

Re: prop grinding

Where exactly are they grinding off? Are they removing some of the cup from the trailing edge? I read the same article and don't quite understand where they are grinding the prop. Here is a link to the article, http://sports.espn.go.com/outdoors/bassmaster/columns/story?page=b_col_bt_1106_Howell_speed

Anyone know where they are removing material?

While on this topic, is there any other prop work that is done to increase WOT RPM without changing pitch or removing cup?

Thanks Jay

 

[imported_bjs]

Re: prop grinding

thats the article im talking about.i need some more rpm's hope works im going to try that trick.

 

[Salmonseeker]

Re: prop grinding

Let us know how it works bjs, Also if you could. Please take some before and after shots of the prop. Just curious what exactly it looks like before and after.

Thanks

 

[jimmbo]

Re: prop grinding

trailing edge of the blade where it meets the hub is where the article says to file. It is very vague as to how much to remove. It think any grinding in this area will cause exhaust gases to be sucked back into the blades and this will allow a few extra rpms. It also reduces any cup a prop has, that too will increase rpms. However, very little thrust is provided from this area of a prop blade, almost all the thrust is from the outer 25 - 30% of the blade. Finally, any grinding would have to be equal on all the blades or else an imbalance occurs

 

[Ron G]

Re: prop grinding

thats the article im talking about.i need some more rpm's hope works im going to try that trick.

What are running and what are you wanting?the bass article was done on a triton set-up and a trophy prop.that dosnt mean its going to work on every prop orr hull more than likly its going to do more damage than good.

 

[Tail_Gunner]

Re: prop grinding

There is a old post somewhere here talking on the subject. I believe Dhadley made reference to some kind of blue printing or balancing issues. In general if i remeber correctly it was advised against doing.

 

[imported_bjs]

Re: prop grinding

by looking at that part of my prop i dont see any cup there pretty much flat.your not going to get much slip grinding in that area vs grinding higher up on the prop.i dont see a balance problem. when only grinding of a small amount.

 

[jimmbo]

Re: prop grinding

Some of my props have cupping all the way to the hub

Poor pic http://pic70.picturetrail.com/VOL1807/7600256/14391838/219375391.jpg

 

[Ron G]

Re: prop grinding

jimmbo you been trying to get to the secret honeyholes?dd

 

[Salmonseeker]

Re: prop grinding

jimmbo,

Nice prop. Just curious, was there any damage done to your motor or lower unit when you bent up that prop?

Jay

 

[jimmbo]

Re: prop grinding

Bent the prop shaft, only had 10 hrs on the boat and motor. Sratched and twisted the skeg but didn't break any off. was only doing 22mph
Neat thing about stainless steel props, the blades don't break off, they just keep hammering into a ball unlike Aluminium
http://pic70.picturetrail.com/VOL1807/7600256/14391838/219686939.jpg

 

[Texasmark]

Re: prop grinding

I only had one prop ground by a prop shop and was supposed to increase my speed. Since they removed some of the blade area, there was less to grip the water and my speed actually dropped. Had no tach at the time so I have no idea as to what it did to rpms. I wanted my prop back in it's original condition as I was very dissatisfied.

Mark

 

[jimmbo]

Re: prop grinding

Were they able to return the prop to original shape?

 

[Texasmark]

Re: prop grinding

Probably could have but I didn't pursue it because I would have had to incur the cost since I asked for the enhancement. Probably could have gotten in a squabble about it as I wanted something and their suggestion didn't work out like it was supposed to but didn't. Happened 20 years ago; forgot the particulars.

Mark

 

[Ron G]

Re: prop grinding

alot of prop shops ha certain ways to grind down an edge,for instance theres a method for bullet boats its called a bullet cut,but it only works on bullet hulls,to grind down a prop for a certain hull for the first time they would have to go through alot of props,any prop shop can add cup and rake.a good prop shop will usually ask what ya want more rpms,more lift etc.and then go from there.a balanced prop is important whem
n running at higher speeds say over 70 and is a must over 80.