black thunder 46

I was wondering where I should start with prop testing? The boats a 1989 31 bullet (knotched transom) with stock Merc 525 EFI's. right now the drives are stock brovos but I'm just not seeing good speed at all out of it I haven't found a good prop. So far the boat has done 73 with a set of 5 blades (can't remember pitch but I think they were 28's). Currently it has 4 blade 26's but it hits the rev limiter immediately and will run 70. I was wondering what other people with similar hp have seen speed wise and what drives they have? I'm thinking I am going to need XR's with 2" shortys but want to see what other bullets have before pulling the trigger.
Thanks

Blackmagic94

If you are hitting the rev limiter you need to go higher pitch. Are they standard bravo 1 non labbed out of the box props.



I highly recommend Auggie at cutting edge props in socal to lab your props. He can change your 26s to say a 28 or 29


i need to know your exact pitch, drive ratio and exact rpm and gps speed and I'll give you a better idea. Tenths count. I'm a prop nerd

Griff

I would try some stock 28 Bravo's to get a good baseline or maybe even some 30 Bravo's. You really don't want 5 blades with the deep X dimension.

class6

Not sure. It I always thought it's way better to pitch a prop down to gain RPMs. Rather than trying to add pitch. I don't think you can get a B1 26 anywhere near real 29.

F-2 Speedy

As Griff stated, Id start with a B1-28p four blade, its not a fast hull

black thunder 46

73mph at 5,300 RPM. Drives are stock 1.5 year ratio brovos and props are stock non landed 4 blade 26 pitch. I am going to put XR with shortys on it this winter but for now I am just looking for the best props to use to run the shootout in. Next weekend.

SB

Course is just 3/4 mile. Would you hit top speed in 3/4 mile with taller props ? Some boats may do better a little smaller.

Blackmagic94

Your slip is 16% which is higher then I like. 10-12 is good on a bravo imo



Labbing to a 27 pitch and gettting th4 slip to 12 would net 78 mph at 5200 or 80 at 5300 if it will rev that high

28 at 5100 is 79mph

Team Archer

Your prop slip is at 20 percent right now. you might want to try a 28 bravo 1 with extra cup. Does the boat still have trim ability at full speed. what I am asking if you try to trim the boat at speed does it slow down right as you start to trim or does the bow not seem to rise as you trim but the prop starts to cavitate?

Blackmagic94

It's at 16. How did you get 20