Hi -- I'm hoping someone can steer me the right direction on this.
Just picked up a 28 Apache a couple of months ago and am starting to do some prop testing. Boat came with hydro 26 4 blades, they were blowing out while trying to get on plane. So I switched to a set of Bravo 1 26 pitch which put me at 5600 rpm, just tryed a set of 28 b1's and rpm's are now 5200, but the boat wants to porpoise at all speeds and in any conditions. This requires tab to settle, and does not allow the trim to be raised too much. Also the boat at speed will start to chine walk slightly at around 75 plus.
The boat is running hawk 525 sc's and bravo 1's with latham steering. I am thinking about spinning the props in to try to get some stern lift, any thoughts??

Dave

OK, assuming Bravo 1's are not blowing out during acceleration(if they are, blows my theory), my solid guess is your X dimension may be too low and consequently your drives are lifting the stern too high...causing chine walk and bow steer at higher speeds.

Bravo 1's are not blowing out at any rpm, I always thought that the porpoising was due to the set-up try to raise the bow and then it falling -- too much bow lift, that's why I'm thinking to get a little more stern lift.
As far as drives too deep -- I checked with Bob Saccentti he said they were where most other 28's were at that time. Not saying that with new prop tech that that shouldn't be changed with say a shorty lower.
I'm new to prop selection and am trying to get all the characteristics straight.

Try the inward rotation.

I think IN will give you more bow lift, but it is worth a try.

From what I've read the 28's like 3 blades.

Did you have any of these behaviors with the Hydros?

Julie

Hi Julie

I didn't keep them on for very long, since they were blowing out. At the time I was breaking in a new engine and it was real rough every time we went out so didn't get to play with it very much. I should put them back on and see if they behave the same, -- good idea.
I think I'll try some mirage plus's also