I have a 21' Revolution ski race boat. 300xs outboard 1.75 gears.
I'm not 100% sure on hull weight but 1000lbs de rigged would be my best guess. The issue I have is the majority of the weight is in the nose of the hull, therefore I have always had to run a very deep engine height in order to achieve bow lift when trimming (110mm below plank)
I have tried the following props at all engine heights from near level with plank to 110mm below. All speeds less skier.
28 et lightening - came with motor, terrible on this hull, hit rev limiter at 75mph and trim did little to pop nose up, even when run deep.
28 bravo - didn't like the diameter and could really feel engine labour. Only seen 80mph and could only rev to 5900rpm. If I added the load of a skier on the back I think it would really kill it.
28 trophy - not to bad. Good out of the hole reasonable mid range punch and 82mph 6200rpm. Towed skier well to. Also ran 27trophy, this was tad slower boat alone but carried skier better.
28 tempest - second best prop. 83mph, 6300rpm. Good off the mark, good mid range, towed skier well.
26 fury - best prop. 83-84mph 6300rpm. Excellent hole shot, excellent mid range, carries skier really well.

Now my issue is none of these props would react to trim until I got the engine deep. Most of them ran same speeds from 60mm - 110mm below plank but drove a crap load better at the lower heights. I currently run a sportsmaster box, which I know aren't designed to run that deep, I have a torque master box here but it blew out at 75mph. I'm working on a small nose cone to stop this. I'm hoping this box will run slightly quicker.

On the topic of props I was wondering if there was something out there better suited again to what I'm already running? I want to get the engine up to reduce drag but still have ability to trim her out for best speed. Would something with big rake do this?
Thanks in advance.
Kurt

No love?

go to the scream and fly forum. They are all outboard go fast guys and may be able to give you a better answer!

Not trying to rub anyone the wrong way but Bblades do props for all boats and I've seen plenty of posts from outboard guys here.
Not that it should matter but i do run all offshore and we all have go fast boats (in our own minds at least). Just after advise from those that are in the know.
My boat is only 21' but I didn't see a size limit on the forum?

Kurt you are not ignored man...one of the guys at bblades will get back to you they are busy as hell and answer piles of emails from web based sites just like oso.

No problems. Look forward to it.

Hi,

If possible you should try a Rev4 four blade prop with shortened tube. The Rev4 is a 4 blade Tempest, and have lots of bowlift. And it can be run relatively high too withhout loosing bite. An old version of the Tempest is faster than the new A48. Try to get hold of a A45 version.

The Sportmaster really slows you down. It works above 85 mph at high transom heights, just as you say. I find it strange that the Torquemaster blow out at 75 mph. It should be good for 85 mph. Maybe it was the prop which lost grip, and the bow dropped? I would put the TM case on again, and do more testing. How much setback do you have? Adding more setback will help, but it may cause issues when towing the skier. Good luck!

Cheeers, Toffen

I didn't think the rev4 came in higher pitches? Been running 27-28 pitch props with exception of the fury. It's ultra efficient.
Currently running 6" setback but am building a 10" solid setback (will be able to change engine height on holes). I have added spacers to get a 10" setback before, didn't affect any handling, didn't run any quicker either mind you.
It 100% blew out with the tm box. Tested in several configurations. I was as surprised as yourself as I thought I could push it out to the 85mph mark before needing to nose cone.
Im adding a very small nose cone, just big enough to prevent blow out without adding too much length and drag to the box.
I owned the tempest I tried but not sure which model it was? Had some diameter cut out of it and labbed to get better acceleration with skiers. Sold it to a mate when I tried and bought the fury. The fury runs almost identical to tempest but a fraction quicker and accelerates better. Like this prop lots but want to get the engine height up and let the prop carry the bow if possible.
Thanks toffen

Sorry for the delay.

I'm actually rather surprised the Fury did as well for you as it did. This prop has little diameter but it does have huge cord length at the hub. It is also a high rake angle. Attempting to get the TM gear case to work sounds like the right idea too since it will create less drag. All hulls are different and even though the TM dosen't blow out at 75 on one hull it may on another.

The information you supplied pushes me toward one specific design. This would be the BBLADES Bravo OB. I would Lab Finish it at a reduced diameter and a special over all configuration to pull hard and carry a skier as well as react strong to trim. We have made these designs for outboard ski racing teams before. The added 4th blade and blade area will work at higher engine heights and the correct Lab recipe will keep it fast and reacting to trim.

Brett

Thanks very much Brett. That helps heaps. What sort of pitch do you think? Want to aim for 6000-6100rpm when towing skier as this is peak power for the 300xs. The fury currently does this and so did the tempest, but there is 2" difference in the pitches of these props?They both would spin out to 6300 with no skier.
I am currently rebuilding the engine as I had a failure but when it's back together I will talk with you some more.
Thanks again.
Kurt