Mariner Prop to Pad question

[Texasmark]

Just blindly jumping back into on this: The 1997 Merc sales brochure states 5800 rpms max with a 1.87 gearbox. Go-fast.com prop slip calculator says that your max possible speed with that running a 23P prop (may be a 24 equivalent at WOT if cupped properly) would be 68. At that speed, figure a slip of about 5% with a good fast hull and high performance SS prop and you should expect 65 on a cool day. If your cupping is working for you then the numbers are 70 and 67.
Course your engine has to be capable of delivering the RPMs under the load at those speeds but it's doable.

 

[logan1297]

Just blindly jumping back into on this: The 1997 Merc sales brochure states 5800 rpms max with a 1.87 gearbox. Go-fast.com prop slip calculator says that your max possible speed with that running a 23P prop (may be a 24 equivalent at WOT if cupped properly) would be 68. At that speed, figure a slip of about 5% with a good fast hull and high performance SS prop and you should expect 65 on a cool day. If your cupping is working for you then the numbers are 70 and 67.
Course your engine has to be capable of delivering the RPMs under the load at those speeds but it's doable.

Those are the numbers that I was thinking as well just from research and experience but I had not done the calculations. That definitely helps support the thoughts on where I believe that I should be, thank you!

 

[Faztbullet]

A good running set-up up will result in a tail 15-20ft behind boat about waist high....On a Charger hull it has the set back sooo….

1) level boat on trailer
2) trim motor level
3) straight edge off bottom of pad and should hti the top 2 intake holes on lower unit,if not its to low.
4) Have prop shop double cup prop
I will get pic's of the Ranger I am working on in AM , as I set it up years ago.

 

[logan1297]

A good running set-up up will result in a tail 15-20ft behind boat about waist high....On a Charger hull it has the set back sooo….

1) level boat on trailer
2) trim motor level
3) straight edge off bottom of pad and should hti the top 2 intake holes on lower unit,if not its to low.
4) Have prop shop double cup prop
I will get pic's of the Ranger I am working on in AM , as I set it up years ago.

Ok sweet! Also, just to clarify I know there are opinions all over the internet but the pad on the Charger hull is considered the step down just above the livewell intake and drain plug correct?

 

[Texasmark]

Ok sweet! Also, just to clarify I know there are opinions all over the internet but the pad on the Charger hull is considered the step down just above the livewell intake and drain plug correct?

Yes.....that's the last of the hull to be in the water at high speeds. Remember, the stern of the boat is below the surface of the water upon which your are running. Therefore after the boat passes a reference point, where the water is lower than the surface, the water rises back up. How far back and how much is determined by the hull shape and speed.

Since the above occurs and you want your AV plate above the rising water, in which the prop is "thrusting" , you have to jack the engine up accordingly as it "sits back" from where the water rises.

Back to a previous answer of yours: you mentioned 6 ½" to the center of the prop. Considering 13" props and roughly an inch between a 13" prop and the bottom of the AV plate, you are still too low, that would put the prop shaft at 7" below the bottom of the AV plate and the AV plate would still be in the water by at least an inch, maybe more depending on trim angle.

If you do as Mr. Faztbullet said, you should achieve your objectives. He does......"SORTA" know what he's talking about, if anybody does.