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Thread: Another prop question

  1. #1
    O.K., I have a 24' tunnel with the 377 6.2 mpi 320 hp, bravo 1.50 and a Revolution 23p 4-blade prop. The boat weighs about 3600 lbs. My problem is my top speed is about 52 mph @ 4000 rpm. Is the prop wrong? I would like to be at least 4800 at WOT and at least into the 60 mph area. What should I do??
    Thanks, Joey

  2. #2
    assuming you are trimming it out after you plane then you are right. your speed is pretty "on" as far as the theoretical math equation goes. you need to spin a 21 pitch at 4800 rpm,s to hit 60+
    has it always been like this, not going over 4k or is this boat new to you. does it plane well? if you can spin that 23p @4800 you should be in the high 60's

  3. #3
    I would love to be in the hi 60's. The boat is new and has been like this. I only have 12 hours on it.
    It planes ok but like I said the boat is new and new to me. I am coming from a 70 mph jet that that jumped out of the water. I am not expecting that but want to get good mph @ wot.
    Also I have heard of test props. Is this something I should try before I buy a new one? And how would I find one?
    Thanks for the reply.

  4. #4
    well we know your boat will not spin that 23 you have at 4800. i would see if you can find someone with a 21p and try it out to see what your boat does. when you trim your outdrive out do you bring it up to the point where it starts to actualy go slower, or the prop starts to blow out. you should bring it out after plaining until you start to feel squirly. that will probably give you your best speed. keep in mind, each hull is unique. don't buy a new prop until you try a few. ask at local marina's tell them you want to buy a prop from them, but need to try a few to see what works best. if they have them and are cool they will let you try it. keep in mind if you mess it up by hitting something you bought it so be careful. keep me posted on how you do

  5. #5
    Hey Cheeter-Joe, 502ProCharger hit it all pretty right on. I am a little more in your league HP vs boat size and I'm pretty sure your problem is prop. That 377 is a great motor and actually makes more HP then my Big Block but unless I'm mistaken it still doesn't quite generate the torque ( I could be mistaken, I often am). I had 1 19' Galaxie V with a bad ass 350 mag in it, even with all the upgrades I stuck on it it wouldn't pull a 23" prop. I ended up with a 4 blade 20" running 57-59 at 4800 rpm. Again I'm guessing but Predator used to make a round eared 4 blade 21" that I'll bet you could turn to 4800 and get into your speed range. Try every Prop you can you never know which one will make your boat happy. I should be at Havasu the 20th of this month if you're around then, I could let you try my labbed 21" 3 blade or (my current favorite) my 23" labbed 3 blade. Good Luck
    Chuck wink

  6. #6
    Hey Joe,
    If you can't find a demo prop pick one up on e-bay. If you are careful, you can get a nice used SS prop for cheap. Once you know you have the right set-up you can either have that prop worked or sell it and buy a brand new one just like it. You should be able to sell them for what you paid for them instead of taking it in the shorts by bying them for $450 and selling at $200. I did this and it worked well. And by the way, your speed sounds about right with that prop on a small block and a 24 ft boat. I would go to a 4-blade 21p. Also, get a GPS if you don't already have one. Good luck.

  7. #7

  8. #8
    I have a 21P three blade prop that would help you put the engine in the right RPM range.

  9. #9
    Thanks for the reply's. This last weekend at Havasu, I tried out the 21p 4-blade. Big difference. I was getting about 4800-4900 rpm and about 60mph. I think that's as good as it's going to get........for now.

  10. #10
    Thanks for the reply's. This last weekend at Havasu, I tried out the 21p 4-blade. Big difference. I was getting about 4800-4900 rpm and about 60mph. I think that's as good as it's going to get........for now.

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