drilling vent holes

[daytrader]

Someone posted a while back about drilling vent holes in a prop. It came from an OMC print out. Being an old f--- I cant remember the post, thought it was in this forum, can anybody help?

[rock]

Hi Gary....What do you need to know.

Rock

[daytrader]

Thankx Rock, it showed where to position vent holes to drill on a 3 blade prop

[daytrader]

Found it under a thread titled: Evinrude 70 prop for speed, started by Flex 4-2-17

[phillnjack]

remember if you want to go to a bigger hole you need to come out and up before drilling.
the omc guide is just for a small hole, I find out and up by atleast another 1/4 inch gives good results for the 1/3 inch size holes.
what prop is this on ?

[vnemous]

Ive been drilling on my Solas Scorpion which just came with like a 1/4" location hole. Up to 5/8" now and hole shot is much better but still not ideal so Im either gonna go up another 1/8" or drill a 3/8" hole ahead of it like I did to my Trophy. Sharp bit, slow speed and some cutting oil. Not to hard to do. JMO

[phillnjack]

it realy is good what the venting does, its like having a 2 speed auto.


when doing the 2nd hole ( if needed ), do you drill at an angle ?
I have only ever done the single vent hole type thing.

.

[vnemous]

381864

[daytrader]

I was going to try it on a no name 4 blade

[phillnjack]

I have vented stainless and alloy props, all with good outcome.

But never tried the two hole method, it certainly looks good.


I normally only drill from 10mm to 12 / 13 mm as its only on a omc 70hp, but would a 10mm vent with a second a 6mm above be
better than going up to say 16mm. ?

[phillnjack]

Go for it Day trader, it realy does transform a slow out the hole prop.
I had a old alloy prop on a 60 merc that you had to wiggle the boat to get it on plane, vented that with just 8mm and it jumped onto plane.
Plus it dont have any downsides to top end from what I noticed.