prop to evinrude 70

[bokarlsten]

Hello!<br />Just hit a rock and broke a blade on my prop.<br />Since I have to get a new I wonder about size.<br />The one I had was 13 1/4 * 17. My boat is just over 16 feet and with the "old prop" max rev was around 5500. Does this sound like the best propsize or should I change?<br />What about theese "pro pulse" props with adjustable pitch. Anyone with experiance of theese. What´s best, 3 or 4 blade props. If I get a 4 blader instead of my old 3 blader do I have to lower the pitch?<br /><br />Greatful for any advice.<br /><br />brgds speedselect

 

[rcgt78]

Re: prop to evinrude 70

Hi!<br /><br />I use a ProPulse on my Flipper 470 GT with<br />Johnson 60Hp -89. I have it at 19" pitch<br />for the moment with a max revs at about 5000.<br /><br />I know that the revs should be 5500 rpm but I<br />think that the carbs are dirty or something.<br />The engine seems not to produce max power.<br /><br />Prop testing data<br /><br />17" (original) 5600 rpm 32.7 knots<br />19" (ProPulse) 5000 rpm ~30<br />18" (ProPulse) 5200 rpm ~30<br />17" (ProPulse) 5400 rpm ~30<br /><br />I don't remember the exact speeds.<br />The boat should however go about 35 knots.<br /><br />I should clean the carbs someday when I have time.<br /><br />Otherwise runs the boat great with the ProPulse<br />prop planning at about 13 knots with low rpm's.<br /><br />The boat is also very stable with the prop.

 

[DJ]

Re: prop to evinrude 70

speedselect,<br /><br />The three cylinder ";loopers" should be propped to turn a minimum of 5500, as yours appears to be.<br /><br />With that said, can you get 5500 with a good load or is that lightly loaded?<br /><br />If it is with a light load, I would consider going to a 15".<br /><br />I can't speak for the switch pitch props. At any rate, the rules still apply as to max available RPM.