Brett, need your help again.

I'm hoping to splash the boat this weekend with the new drive and the 21P prop that I currently have.

I remember we were talking about running a 23P Mirage Plus and I may be able to try one over the weekend (a very good friend is going to loan me his while his motor is being torn down). Anyway, I've been doing some reading and have seen it mentioned a few times that a Mirage Plus behind an Alpha would actually cause performance to drop across the board. Merc seems to mention only the Bravo when talking about the Mirage Plus. Any ideas on that one?

To refresh your memory....

1983 4 Winns Cuddy 23.5' (same hull as Liberator)
383 Chevy
5600-5800 RPM target
4k Pounds
1.84 drive ratio


Thanks!

Tom

Back in the mid to late 90's the Mirage and Mirage Plus where suggested propellers for the Bravo drive, the Alpha drive and large outboard applications. I actually have a 1996 accessory guide in my office that suggests the Mirage propellers on Alphas. Currently you still find the Mirage Plus listed under Alpha applications (pa. 102-104 Mercury 2005 Propeller Guide). You will need to check steering tab clearance before running the small pitch Mirage though.

The fact that you have the opportunity to run one is reason enough to try it this weekend. Remember Lab Finishing will bring an additional 300rpm and speed if it is there to be gained.

In some heavier cuddy's with slightly under sized power, the Mirage Plus will offer good performance until the top end and then may lack luster due to drag. Those boats perform better with Laser 2 propellers as far as top speed is concerned. I don't believe that to be the case here. Try the propeller and lets use your findings to evaluate your needs further.

Once again, test, test, test!

Good morning Brett.

Well, I ended up being a couple of weeks late getting her out on the water, but I managed to on Monday, but I wasn't able to use the Mirage like I had hoped, so I went out with my old 21P Vengence (I think that's what it is). Here's what I found...

At low speeds the prop handles the boat well.

Acceleration at low speed was great.

Hi-speed running is another story.... loafing along at roughly 3k RPM (while letting the drive break-in) I'm running about 20 kts. If I crank her up to 4k RPM I maybe see 30 kts, but it takes for ever to get there (the motor spins to 4k RPM immediately, but the boat doesn't pick up speed). When I push her to 5k RPM and above (short bursts), the boat doesn't seem to move any faster.

During all of my running, it seemed like the motor wasn't laboring at all. It seemed to be pushing the boat effortlessly. I didn't detect any amount of strain. It almost seemed like the motor was freewheeling most of the time.

Any thoughts?

ttt

The Vengeance 21P runs at 13 3/4" diameter. I think your overpowering the propeller and it is slipping terribly. The Mirage 21P and 23P run at 14 5/8 and 14 1/2 respectively. The additional blade area should be able to harness the power.

Another crazy thought might be the hub has rounded the delrin and it is actually spinning the hub under load and high toque situations. Just verify this isn't the case.

There is another propeller called a Ven-Sura that may give you the all around performance you need from low end to WOT. It will sacrifice some speed but help everywhere else.