prop selection help

chuckcrick · 04-21-2007, 02:02 PM

Help! I own a 95 31 Scarab. I was forced to repower due to a broken crank. Needless to say I have a lot more power now so I need different props, and in a year or two new outdrives.

Elevation where I boat is 2152 ft, I am running bravo 1 drives (1.5) with twin 540 carbureted motors. I was running 24p bravo 1 4 blades with my stock 502's. I do not want to exceed 5600 RPM. Estimated horse power is 600 to 650 per engine.

Any suggestions on what type of prop and pitch I should start with? This year of boat is heavy so I was thinking 30p. I would also like to have a prop that will work when I upgrade my drives if possible. Thank you.

Griff · 04-21-2007, 02:23 PM

I think 28 Bravo 1's would be a good starting point.

oldandtired · 04-21-2007, 07:01 PM

I'm guessing the weight of the boat to be around 8000 lbs. It should be able to run high 80's and a 28-30" prop seems like the right choice with 5600 being target rpm. I am basing this on about 1100 total shaft horsepower. I second starting out with the 28. My guesstimates put that boat around 67-70 with the old power. As far as props being upgraded, you should just need the XR hub kit if you are using a Bravo 1 prop. If you use a prop with a fixed hub, you'll probably need new props. I am assuming that by upgrading drives you are talking about going to an xr.

Rene

gsmith9898 · 04-21-2007, 07:31 PM

I have a set of labbed 28"s

chuckcrick · 04-22-2007, 10:16 PM

Thanks for the advice.

I am glad I posted this because my rationale for thinking a 30 pitch was what I needed was because I have a friend with a 38 Scarab AVS with twin 500's carbureted and he is running a 28 pitch. He runs out low 5's for RPM and 72 MPH GPS. I realize his boat is more efficient but I didn't think that much. I am running a minimum 200 hp more then he is and at least 2k less in weight then him. I guess I was looking at it the wrong way.

Thanks everyone.

As far as Labbed 28's; thanks but I am very much a recreation boater and I will probably buy standard props. We have too much junk in our lake and my investment in labbed would not last very long. I am figuring $500 to $600 for the set which is what I will get for my 24's. Again thanks.

bbladesprops · 04-23-2007, 07:40 PM

Hi Chuck,

I recieved the email. I agree with the 28 pitch Bravo 1 as the starting place. Doing the calculations brought me to the 4 additional inches of propeller needed. There may need to be some minor adjustments to the propeller after you run them and get a baseline.

Be careful buying used propellers. Ask questions about the age and any repairs or rework that may have been done.

Brett

mboger · 04-23-2007, 08:35 PM

i think i would be careful with the drives if they will hold help

chuckcrick · 04-24-2007, 08:26 PM

Quote:

Originally Posted by mboger

i think i would be careful with the drives if they will hold help

I agree, XR's are on the list. I will have to baby my drives until I get new ones. Pocket book only goes so deep.

Thanks for the post.