Making a push prop on the cheap.

Franki

Lieutenant Junior Grade
Joined
Feb 16, 2002
Messages
1,059
Hi Guys..<br /><br />I have this little Chrystler 6HP outboard that is my emergency "get home" kicker motor..<br /><br />The boat it pushes when needed is a very heavy 17 foot fiberglass half cabin. and left as it is, the little engine will become the "little engine that can't" because the engine has to work very hard to push this boat..<br /><br />The prop on it now is a two blade 8x5,, is it possibly that its already a push prop?? It certainly doesn't seem like it would displace alot of water.<br /><br />So, I need a push prop (if its not already), but don't have much cash to spare for it..<br /><br />I asked around, and someone said that I can achieve similiar result to a push prop by carefully evenly cutting the tips of the blades of the prop,, apparently you can make a good test prop for using in tanks the same way.<br /><br />Does anyone have any comments on this? how do I know how much to take off?<br /><br />I know I can cut it evenly, I'll get a felt tip pen and rotate the prop to mark where to cut.. then file it down to as perfectly even as possible. but how much to take off??<br /><br />I am not sure I could get a push prop for an old chrysler 6hp even if I did have the cash to spend on it.. but by the same token, I don't want to fry this thing by overloading it if I need it because I am stuck somewhere..<br /><br />any thoughts you guys may have would be much appreciated..<br /><br />rgds<br /><br />Frank
 

sony2001

Chief Petty Officer
Joined
Mar 17, 2001
Messages
607
Re: Making a push prop on the cheap.

Possibily a more accurate way of reducing the pitch is to felt line one end then make a paper (or plastic) pattern of the piece to be removed. Move the pattern to the other side to make the felt line. With the pattern there is a greater chance of removing the same amount of metal from each side. :cool:
 

JB

Honorary Moderator Emeritus
Joined
Mar 25, 2001
Messages
45,907
Re: Making a push prop on the cheap.

Hi, Frank.<br /><br />Is your kicker "working very hard" by revving too high without getting headway, or is it bogging without reaching full rpm? If it is reaching full operating rpm (5500rpm) you cannot increase the thrust.<br /><br />What you propose will cause the engine to rev higher, but if it is already reaching peak rpm your thrust will actually be reduced, not increased, and the engine life will be in jeapordy.<br /><br />I don't like your solution. There would be no way to "un-cut" your prop.<br /><br />Good luck. :)
 

Franki

Lieutenant Junior Grade
Joined
Feb 16, 2002
Messages
1,059
Re: Making a push prop on the cheap.

Thats the problem,,<br /><br />Its only a 6hp, and I have no idea what its currently doing at WOT.. it feels like about 4500, but I really don't know, thats more of a guess..<br /><br />I thought maybe it was 5.5k and that it must already have a push prop, i just don't know..<br /><br />any tips for how to tell rpm on this thing? there is no wiring harness... its all self contained magneto...<br /><br />rgds<br /><br />Frank
 

petryshyn

Commander
Joined
Oct 3, 2001
Messages
2,851
Re: Making a push prop on the cheap.

can you borrow an inductive timing light(with tach), photo tach, or mechanical tach for the top of the flywheel?
 

Franki

Lieutenant Junior Grade
Joined
Feb 16, 2002
Messages
1,059
Re: Making a push prop on the cheap.

Guess I am gonna have to find a way to test it..<br /><br />its gonna be hairy trying to test the rpms mechanically while on the back of the boat, its on a bracket way back past the stern..<br /><br />it just never gets easy does it..<br /><br />I was wondering if there is a way to find out what type of prop I should have, and then compare it to mine.. 5x8 2 blade..<br /><br />I suppose the old holes in the prop trick might make things easier on the motor as well.. but the idea of a weakened prop spinning fast near the back of my boat alittle scary.<br /><br />I'll ask around if anyone has anything I can bottow to test this, but I am not confident.<br /><br />thanks anyway..<br /><br />rgds<br /><br />Frank
 
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