The Menace

I had a new set of Bravo props 28 x 15.25 for the Top Gun.

They were lab finsihed (?, I think). Put them on this past weekend and I lost 4 MPH in relation to speed before they were shipped out. What happened?

I picked up a set of Merc test 28's the same size, ran them last night and I am back up to my old speed.

I measured the diameter and width of the blades as well as an novice could and saw little difference if any. I know the cupping is important.

My buddy showed me how he could tell if a prop was lab finished for balance by Mercury becasue of grind marks at the tail edge of the blade for balancing.

These things were polished to perfection.

Opinion? Comments? Can they be fixed?

PS: I already know I am not going to get any help from the proposed experts that did them.

Smitty

iTrader: (1)

Sounds like you need a little more cup in them. Who did the work?? Are you hitting the same rpm as before, but just lost speed??? If that is the case, I have experienced the same thing and added some cup to the blades to fix it.

The Menace

Before I was running 4800 rpms. Red line 5200. Runs right up to 5500 with throttle left to go. Not enough of something.

zt260

I have had the same problem in the past. Many so called experts will lab a prop by taking all the cup out of the blade, this results in increased rpm but rarely a speed increase on v hulls. If you choose to have any future props labbed tell them not to take any of the cup out. Thats what I did and I gained 2 mph without much rpm increase. Sorry to see you had to learn the hard way just like me.

I don't know if much can be done with these labbed props now, maybe someone can jump in. It might be time to start over...

Audiofn

A highly polished blade does not mean that they did not lab it. You repolish a blade after you do any work to it. Satin finish is sapposed to be a hair faster but also corrodes faster so most people with pleasure boats opt for the high shine. The people that reworked it had no advice for you? Did you give them a chance to fix them? I have seen people loose speed when they have had their props repaired by a place up this way but most of the guys on this board I have heard nothing but good things about.

Jon

Smitty

iTrader: (1)

Since you are in Florida, call Matt at Throttle Up propellers. He is an OSO advertiser and from what I have seen here does outstanding work. I'm sure he can correct your problem.

Cord

iTrader: (2)

Run your finger over the leading edge. Does it feel sharp? If so, then it's a "lab finish". If not, then it was proably trued and polished. You will lose a couple in that nice shine.

HOUSTONPROP

express cat,
give me a call and I, will be glad to help you out,

Houston PROP.

Darin

throttleup

expresscat39,

Did you send the props in to be lab finished?

You gained a lot of rpm, typically you should see an increase of about 200-300 at wide open throttle.

The finish (polished or stain) has nothing to do with the "lab finishing".

Have you talked to the shop that did the work? It's not unusual to have to make an adjustment after props have been lab finished.

Thanks for the kind words bigwavz.

If you have some questions don't hesitate to call.

Matt

The Menace

Thanks for all the input guys.

Darin, I treid to call but no answer will try back later.

The props were sent out to be "lab finished".

Today they are on their way back to the shop. I am sure it will be a while before I see them again.

A little frustrating but I have learned several lessons. These several lessons have been added to the 4,987,000 volumes that wall paper my life. By the way, I am the one not holding the sign.