Voo-doo  Prop

Hi guys, I have another question for you. I finally ran my voodoo with an 83 70hp merc. The motor is mounted flat on the transom. The problem I have with it is, just as it starts to breaks onto plane the prop cavitates. If I rev it and lean over the front I can get it on plane and eventually get the prop to bite. I am going to run a 19p aluminum this year, will some added cup help this, if so do you add the cup to the leading edge or tip (maybe both).

If you have any ideas I’m all ears as nobody around here has any suggestions (other than shortening the transom!).

PS: the gear case has 1.83 gears.

Brock,

Stick with the set-up that you have, but maybe add a planing plate to the cavitation plate.  Adding cup to the tip and de-pitching the leading edge will solve the other problem and add a few mph. By de-pitching, I mean to "roll" the leading edge. This makes the prop have a more progressive profile.

 Randy

Please submit whatever questions you have to IHRTechTalk@yahoo.com.  All questions and answers selected will be displayed on this page as they come in.  Note: though all boaters are welcome, priority may be given to I.H.R. members.  Randy can not be held responsible for any advice given.  Though his information and expertise is second to none, he has no control over what you do with your boat.  It is up to you to boat safely and act responsibly, and his advice is only to be used as a guidance for your high performance boat/motor of which you are the one responsible for the risks involved.

Thanks,
Mark C.

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