Builder Bob

undefinedWonder if we have any wingnut experts ouy here that could give me some advice. I have a 1984 Formula SR1 302. Twin 502s with TRS drives, counter rotating. Port spins out, starboard spins out. I purchased the boat with 15 1/2x25 four (4) blade Intimidators which turned supposedly turned 5000-5200 RPM throttles on the dash in full trim with 1-2ft chop. Previous owner says it ran 72MPH with this setup. I could only get these props to spin at 4600-4800 with speed approximately 65MPH. I have no speedo or GPS, just what other boats running with me said. Should I go down to 24 pitch Intimidator four (4) blades or Bravo 1 four(4) blades?? Anybody have any real factual solutions? Thanks for your responses.

Builder Bob

bbladesprops

First you need gps and true tach readings!!

Next, your boat needs props to carry the bow, not the ones you have. However, you efficiency isn't bad if the numbers you have are correct.

We would suggest rounder eared props.

throttleup

Builder Bob,

Are you trimmed for speed at the 65MPH? If so, I would recommned that you get a hand held and get an accurate speed reading. Has anything happened to the props or are they in good shape? If your trimmed for speed and all you can get is the 4600-4800 RPm then you will need to increase your RPM to 5000 at WOT (502 is rated for this). There are several options that we can look at to increase the RPM.

Julie

Builder Bob

Well, I am planning on purchasing a GPS this winter. If I go to a 24p 4blade will the RPMs pick up as much as I need? The boat pulls out of the whole and on plane fantasticlly with the 25p Intimidators. Just looking to turn more RPMs I guess. What are your suggestions on props?


Thx,

Bob

bbladesprops

Yes, to answer your question. 1" of pitch decrease will raise your rpm about 200. It may not offer any top end gains and may cause you to loose 1 mph in the mid range.

My first thoughts are Lab Finished Bravo 1 26 pitch.

If you really like the props you have, they can be adjusted to gain the rpm needed. We would need to see them first though to varify what we are starting with.

Accurate numbers are a must.

Mono Powerboater

Hi Bob,
speed depands on a lot of things. Like water conditions, are your props still very well balanced, are they razor sharp and pollished, how is the drive hight setup did you change point of gravity?? A bit of small waves can make a boat climb in speed. A wet running boat slows you down. Do you have a running picture that could show a bit more?

throttleup

In order to be as accurate as possible we will need very specific performance numbers from you. I will need to know exactly what yor WOT RPM is and speed via GPS. I just do not want to chase any ghosts and overwork your props.

Julie

Builder Bob

Well, there is a small problem here. The main reason for all the questions without any real evidence is that I smoked a sand bar on Monday on the way to the ramp. So, both props are damaged maybe beyond repair. Therefore, i was going to purchase a set of props to replace those and probably get them repaired. So, having had these props a I was curious about a few things. Some say get Bravo 1s and the cupped (4) blades and still others say stay with the Intimidators and reduce the pitch. My buddy Greg Reno, a.k.a TIZBAD, mentioned that I could buy a set of props, try them out and if I didn't like the performance I could return them for a restocking and shipping charge and try another pair. Any truth to this? Sorry to be a pain in the azz but I just bought this boat and am experimenting with the props.

Cordially,
Bob

bbladesprops

If you would like to test some Bravo 1 propellers, please give us a call at the phone number listed below.

Thanks.

throttleup

Builder Bob,

Then testing is a definately the way to go. We have a testing program available to anyone thaat wants to better dial in their boat. Feel free to call me anytime and I will go over the program with you.

Julie