Propellor modifications.

jurgenscraft

jurgenscraft

Petty Officer 1st Class
Joined
Nov 6, 2004
Messages
227
I recently saw a article relating to holes being drilled through the sides of the proplellor, venting exhaust fumes out the side, I think ??. are there any advantages in doing this modification,and what is the purpose of this modification.Surely the possition and size of the hole drilled must be critically possitioned and sized,Kind Regards William Wright.
 
G

gutshot grouper

Petty Officer 2nd Class
Joined
Aug 29, 2004
Messages
110
Re: Propellor modifications.

What did the article say? Surely the author had something in mind unless he gets his kicks drilling holes in stainless steel.
 
Silvertip

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,762
Re: Propellor modifications.

Its called prop venting. Some props come with the holes and various sizes of plugs or inserts to vary the size of the holes. At initial start, the exhaust exits these holes at the transom side of the boat. This creates a little turbulence and allows the engine RPM to rise briefly to provide better hole shot. It provides no benefit at cruising/high speed. Hole size is critical as is placement. Holes size is experimental. Start small and work up if drilling.
 
tommays

tommays

Admiral
Joined
Jul 4, 2004
Messages
6,768
Re: Propellor modifications.

f38a0259.jpg
<br /><br />worked good for me but i tested on some beater props first<br /><br />its like everything else on a prop no two boats need the same thing<br /><br />tommays
 
jurgenscraft

jurgenscraft

Petty Officer 1st Class
Joined
Nov 6, 2004
Messages
227
Re: Propellor modifications.

Tommays.Upinsmoke and gutshot grouper, Thank you very much for the reply to my posting, and thank you for the photograph showing me what propellor venting is all about, what size hole did you begin with and what size hole did you end up with and how far away from the propellor edge is the centre of the drilled hole,what effect has this process have on cavitation if any,is there a website some where that has information regarding this matter. kind regards William Wright
 
S

shep70057

Petty Officer 2nd Class
Joined
Oct 16, 2003
Messages
115
Re: Propellor modifications.

Be careful not to drill too big of a hole. If you do that, your prop will be useless until you get someone to weld the holes shut. Key is to start out small until you get the desired affects.
 
tommays

tommays

Admiral
Joined
Jul 4, 2004
Messages
6,768
Re: Propellor modifications.

i went with a 1/4 in hole its 5/8 from the blade and 5/8 from the step<br /><br />you have to look inside the props are different and you dont want to drill into the braces<br /><br />the whole idea is controled cavation at low speeds <br /><br />if you have a big dollar SS prop i would be carefull<br /><br />tommays
 
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