Flat Acme tips

[backman]

I ate a shark 2 trips ago, noticed one engine running 1/2 GPH higher than the other and drinking 5% more fuel over a couple offshore trips. Worse; that engine was down 60-70 RPM at WOT.

Swapped props and the biatyard found as I suspected; one flattened blade tip and scuff from the shark, but more surprising; the tips of both blades all had flexed almost flat.

These are Acme 18 X 26's; have been run hard for ~225 hr's so far this year.

Anyone else have this experience w/ Acme's?

[Patriot]

Acme

Larry-

When you say "both blades" I assume you mean both props, all blades? Are you saying that the cup has straightened out on all blades? If so I would talk directly to Acme. A possible hardness issue is all I can think of.

[Split Decision]

I have bumped bottom more than once and my blades are OK. I think I might have knocked them out slightly because I have a slight vibration but the blades look fine. I would think it should take more than a shark to bend the tips. I could see knocking a blade out slightly but bending a tip is tough to do on something soft.

[backman]

Both props/all blades

The cup has flattened out across all 8 blades. One was flat and had a scrape/rough spot; ie shark.

I do this twice year on either sharks or mola's. The blade tips are really thin cross section and do bend when you hit something at high RPM's.

Now; w/ my new prop's on the problem is reversed; the other side is 1/2 GPH higher and only got up to 3560/60 RPM below the other.

Arghhh. I will call Bill Weeks on Monday, but my mechanic points out that this is the drawback of the highly tuned and aggressive Acme's; they are impossible to keep in sync. if you run the boat hard like I do.

[Hey Doc]

18 x 20.5

I looked at my blades today and while the cup is not completely flat, it appears that about half of the blade tip is getting flat. I only have 100hrs on these props, anyone else seeing a similar pattern to backman's?

[Patriot]

Acme doesn't put the cup on the tips for any CC props I have seen. The cup on Acme props runs for what appears to be about half of the trailing edge, by the time you get to the tip there is no cup by design.

[Hey Doc]

After talking with the Factory

After talking with the factory and taking a more careful look at my props, it is clear that I was mistaken in my earlier post. The cup in my props has not flattened out.

[backman]

sorry

This dropped by the wayside as my mechanic and I have been chasing a top end loss of power and a bit of steam and smoke on one engine.

After 6 $sea-trials w/ Vodia present and much discussion w. Volvo its been identified as a faulty manifold air temperature sensor which is reading air temp at 80 degrees no matter how hard the boat is running.

new sensor is on the way; we'll see if it cures the smoke/top end loss; then I'll go back to chasing down the props

[Patriot]

Glad the "Acme prop losing cup is solved". They are great props.