Vegas/OMC Prop Advice

I am in the process of reworking my 1988 hull schedule to be finished July 4th.  I am completely re-rigging from skiing the kids to going fast.  I have added a 10” set back and Bob's nose cone and hydraulic steering now......what prop? 

The point is I am a 120 female reworking this boat.  It looks great and I wanna go fast.  I have the racing experience.  I have been given many choices of props...which one is the right one.

I am running a 20 foot Vegas hull with an OMC 200.  It is my understanding that I should be able to run at least 82mph.  My reworking the hull has made it approximately 150 pounds lighter. 

Also, confirm my math of motor setting = 1/2 inch height for every 1 inch set?

Please reply.

Thanks
Tammy

 

Tammy,

Sounds like you have a nice project boat being formed. Here is my honest opinion. The Vegas with the OMC should run around 5" of set back. At 10" the 450 lb motor will cause the boat some bad handling characteristics compared to 5" or even right on the transom. I've set up the Vegas with a 225 Yamaha right on the transom, 1 1/2" up and had it run in the low 80's. There is no reason yours shouldn't do the same. The cone is good. I'm not entirely sold on the hydraulic steering for 80 plus boats. I've rigged and driven them and the owners and myself find the boat a little more difficult to control than with mechanical steering. It ok, but you'll find the corrections to keep it on the pad are different than the norm. The 1/2" for 1" set back formula is not a given. It depends on the total set up and the boat angle of attack. I don't know where the figure came from but disregard it. For now set your boat up with the 10" jack with the propshaft centerline 1 1/2" below at neutral trim. This is a good place to start. It might be a little low but only go up till the wheel torque starts and the roostertail is getting higher than the motor. If that happens go back down a little and you’ll be set. For props a 27 or 29 OMC SRX would be good. Any Mazco RE3 or big blade chopper around 28 pitch would also be a good choice. Make sure of a foot throttle and that all steering play is taken out and you should have a good ride. If the boat is flighty and kind of unruly to drive at top end take half the set back off. The boat is more predictable with the weight closer to the center of gravity.

Good luck with your project.

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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