4 blade Rolla's
 

How much if any can you increase the pitch ? I have 171/2 x29 right now. Thanks.

Re: 4 blade Rolla's
 

It depends on the prop. Depending on the blade design we can usually increase the pitch an inch, sometimes more and sometimes not at all. Typically with speedmaster style props I scan them on our computer and then make a decision from there.
A common problem with the speedmaster style props is that the cup gets washed out after being worked. If this is true with your props then restoring the cup may help reduce your rpm, if that's your goal.

If you have any questions give us a call.

Matt

Re: 4 blade Rolla's
 

Usually a maximun of 2 inches.

How much rpm do you need to lose?

Brett Anderson

Re: 4 blade Rolla's
 

I need to lose about 500 to 600 RPM, this is on Arneson drives . If these props wont work would I benefit by going to a 5 blade. Will this give me more stern lift, would realy like more bow lift. Thanks for the reply! John.

Re: 4 blade Rolla's
 

We may be able to pull 4-500 rpm out of the props. 5bl's will give you more stern lift. There are some progresive things we could try with your props. It would help to know more about your application. Let us know if we can help.

Brett Anderson / BBLADES Professional Propellers
920-295-4435

Re: 4 blade Rolla's
 

John,

Some of the Rolla props are cut a certain way to increase the stern lift. The props can be worked to reduce the stern lift if yours are this way. You may find that just by reducing the stern lift the stern will settle down and your rpm will come down as well. We would want to look at your performance numbers to determine what the boat is doing.

Without knowing your performance numbers I wouldn't do anything drastic to the props. By up-pitching them you may end up increasing your slip and possibly loose performance.

What boat, year, engines, gear ratio, speed@WOT and rpm@WOT. If you have built motors do you have dyno sheets for them?

Matt

Re: 4 blade Rolla's
 

39 Ocean Express 1994, Arneson drives 1.3 ratio dont have dyno no,s but should be in the 800hp range have not run boat much since It was built except for short shake down runs. Once it is up and running and I increase the rpm it seems to blow the props out. I have run other 39's with about same set up and they stay hooked up. Dont know if I am over powering the prop or what. Thanks! John.

Re: 4 blade Rolla's
 

John,

The best place to start would be to have your props looked at. Very frequently when a set of speedmaster props come in and they have been worked in the past they were hacked on. If your props were worked on in the past it's possible that work is causing the problems you are having.

When we diagnose speedmaster props we first check them with our computer to check for such things as pitch, rake, cup, chord length, track, blade position, pitch progression and diameter. After that we do a visual inspection and go from there.

This is what one our typical speedmster props looks like when it leaves the shop.

Re: 4 blade Rolla's
 

That sure is a pretty prop! Does the polishing help reduce slip?

Re: 4 blade Rolla's
 

bob,
The polishing is mainly for looks. It does help to reduce the corrosion. Some claim that a satin prop is faster than a polished prop but in real life conditions I haven't found that there is a difference in speed between a satin finish or polish finish prop.

Another factor about polishing is that is really shows off the quality of one's work. You can hide a lot behind a satin finish but when you look at a highly polished prop it's like looking at a car. If it's not right you will see scratches, waves, bumps, etc in the finish of the prop. We finish most of our props with a polish finish unless the customer asks otherwise or the prop has a satin finish when it comes in.

Matt