Prop help

[89Mach1]

Ok, so I have a few questions. This is my first boat with a 454/330 merc and bravo 1, all past boats have been small blocks and alpha's so maybe I just have to get use to the extra power I now have.

The boat is a 23' Mach 1 454/330 w/ bravo 1

23p Mirage (stainless)

WOT 4850 rpm @ 62mph

I think for the most part I'm pretty pleased with the prop, I think it carries the bow pretty well, I see water breaking about where I stand in the boat, maybe 6-8' forward of the stern.

My big question is I noticed the prop loosing it's grip a little during planing. I get just about on plane and hear the motor start to rev, so I back off a touch and it grabs again and keeps going no problem. Then I notice if I bring the drive up too quick it loses grip again, so I back off a touch and no problems. I don't hammer on the throttle, I ease into it so I know that's not the problem.

Is this something normal for a BBC to do? Do I just have to get use to it? Any help or suggestions would be great, and thanks in advance!

Jay

[Ratickle]

I'm not a guru, and I'm sure you'll get better answers. The Mirage is a 3 blade prop, and depending on your X, which sounds about perfect from your description of what is happening, you should be able to go to a 4 blade with about 1 inch less pitch. But, as far as which one? You'll have to ask the pros and I'm sure they'll be on...

[89Mach1]

I was thinking of trying a 4 blade, and I suppose this brings up another question. I believe I am 250 rpm over what merc recommends (4600 WOT) so I would think I need the same or 1 pitch up? I can get my hands on a Bravo 1 4 blade, 24p for CHEAP! I may be able to try it first, but even for the price he wants I should probably just buy it anyways.

I thought the 4 blades help to lift the stern and don't carry the bow very well?

[MOBILEMERCMAN]

If you can try the other before you buy it try it. I have always propped the 330's between 4800 and 5000 r's. Most sport boats seem to benefit from that. The prop slipping as you come on plane just as the bow falls is an indicator to me it has a nice set up. It should not lose thrust or free wheel just slip a couple hundred r's. IMO

[89Mach1]

If you can try the other before you buy it try it. I have always propped the 330's between 4800 and 5000 r's. Most sport boats seem to benefit from that. The prop slipping as you come on plane just as the bow falls is an indicator to me it has a nice set up. It should not lose thrust or free wheel just slip a couple hundred r's. IMO


You're right about it not losing thrust, just revs the motor a couple hundred rpm. If I leave it be it recovers on it's own (few seconds, if..). So basically what you're saying is it's just the nature of the beast? If so that makes me feel a little better.

I'll see if I can try out the bravo 4 blade, just for the hell of it. The guy only wants $150 for it, and I'm going to be doing some work for him on his boat tomorrow so maybe he'll let it go for even less!!

[PARADOX]

Don't worry... you'r ok. I got the 454 mag and bravo and 23" mirage on my Infinity, and have similar issues. Not often,, but it's normal to have a higher tourque motors loose a little grip. Just be carefull and your set up is right.
4 Blades might help, but I doubt it's worth it. If you can,, try to add a little cup into the Mirage.