throttleup

Tomcat,
As a general rule cats don't need bow lift, in fact many of them attain max speed with negative trim. That's why they typically respond well to multi blade props. The Bravo 1 prop is the most versatile prop on the market in that it will work respectably well on just about anything that floats. It may not be the best prop for an application but it will work. The Bravo 1 has proven to work well on cats but usually at the expense of getting on plane well and without the acceleration a multi blade prop can offer.

The only way to find out what is the best fit for your boat and style of boating is to try different props. Two identical boats but owned by two different people may have different props on them due to the different style or driving and the type of boating they do.

We will do some testing this weekend in Ft. Lauderdale with a cat and P5X's. In this case we are trying to settle the stern down caused by large diameter 6 blade props.

Matt

tomcat

Brett: Thanks for answering. I hear what you are saying about multi blades being a fix for something else, like excessive drive heights. From my own experience I know that adding a blade just slowed the boat down until I also raised the drive. This gave the best speed but even with the extra blade did not have has much bow trimming ability as less blades deeper in the water. This was in a test of Mirage Plus vs. Bravo with and w/o 2" spacer.

Matt: Thanks for answering, if you can tell some specifics of the cat with the six blades. When the stern is lifted too much are you concerned only about handling or does the bow drop in reaction and cause slower speeds?

bbladesprops

Troutly,

I sent it last night at about 7:30. Must of been too long again and didn't go through. I'll rewrite.

Chris288

Matt,, did you end up getting a 25p P5-X that I could try ??? Thanks Chris..

throttleup

tomcat,

We have yet to have a cat lose speed with a 6 blade. We have 6 blade props on everything from 28 Eliminators to DCB's to Skaters, Spectres, ect. Some have big power and some are stock 525's. Some are running over 150 mph. Some have slip as low as 3.5%. We have not had any issues with excessive stern lift with any of the cats as well as any of the V bottoms that run our 6 blade props. Including those that typically like bow lift. The prop can be worked to reduce the amount of stern lift, if there may be a problem with that.

We have had outstanding success with the 6 blades on many single engine v bottoms. Including the Super V Lite class race boats.

It's more likely for a cat to lose speed when the stern is dropped with too little stern lift. The air in the tunnel can not escape thus slowing the boat down.

Before we sell a six blade prop we try to make sure the customer's boat runs well with it and make sure the 6 blade prop will meet his goals.

Matt

bbladesprops

troutly,

Please email me so I have your email address. My message was too long again and I don't want to condense it.
[email protected]

Cats definately like stern lift as a general rule. They are like an airplane wing and must fly flat. We have found some cats that don't need as much as others. We cut diffusers off some surfacing props on some cats to decrease the lift.

Of course if you pack too much air in the front of the tunnel, from not enough tail lift, it's like a wall and the cat actually porpoises.

It's hard to compare a race boat with a standard lay up pleasure boat that has the CG in front of the helm. Especially V's.

There is no reason to defend the 6BL propellers. When they work, they are awesome. As pointed out before, High power, high X dimesions like a larger diameter shorter deration from load to unload type of propeller. That's why cat's and race set ups love them. Not 36 Baja's.

Are we repeating ourselves here?

If you get the chance to try any propeller on your boat........do it! You must decide what works best for you.

shockwave07

I have an 07 25' shockwave and am looking for any advise that could be given on what prop works best? is there any one out there that could help me out? i have instaled Dana Marine headers and have a 496ho. I am looking for top end as it seem that the motor has all kinds of mid range.

bbladesprops

The largest pitch 4 blade propeller Labbed to get into the upper end of your desired rpm range should give you the best overall performance as well at top speed as long as we end up in the 9-13% slip range.

shockwave07

so i was thinkng a brovo 1 26?? what about a maximus 5 26? boat has great bow lift already and X dimension is about 2'' up im new to this and trying to understand everything that goes into it. thanks again.

wuped

Here are some numbers from some testing I've done with three different props. As you can see the lower-range with my boat really improved with the larger diameter Maximus.