302Sport

Only have 17 1/4" diameter props on my 50. Should I be running 18" diameter props or even bigger if I can find some custom stuff??

SS930

If the props are coming in and out of the water, you might have a serious issue with keeping the props and or drives intact. I would think larger diameter props would be more prone to tossing blades. With that said, it takes some serious water to get my props on the 46 to come out of the water and I would think your 50 should be even more difficult to air the props out. The few times which they have come out of the water has been out off BI or out near Montauk... I don't think I recall ever really needing to throttle the engines inside LIS, so that will hopefully work in your favor.

Anyway, I would think you'd want to limit the diameter for longevity if you plan on running the boat out to BI very often, which I'm sure you will.

302Sport

Not worrying about drives anymore. They are going to Collabella then we are putting in slip clutches/torque limiters. The drives should live now as they were going about 60 hours between rebuilds before. During testing they were seeing 2500 ft/lbs of torque on re-entry into the water. We are most likely going to set the clutches to slip around 1500 ft/lbs. I think these are really a game changer for keeping #6's together on the turbine boats.

bbladesprops

Diameter adjustments should be made if there is a boat attitude issue, a slip issue or other propeller related things. I think you're probably fine at 17.25".

Post some performance numbers and seat of the pants observations and we can discuss it more.

Brett

302Sport

My props are at your shop. When are you going to be back from Miami?

hogie roll

Is that a test from your boat or testing that they did? Where did they measure it?

302Sport

That is from testing done a 42 Fountain with 700's and #6's. The torque was measured by a torque meter on a laptop.

bbladesprops

I'll be back Thursday. It will take me a day or two to get organized. I'll contact you with all questions.

Brett

hogie roll

There has to be some instrumented component in the driveline to determine that. I was just curious where or what part it was.

I'm not sure how the inertial mass of a 700 compares to your turbine, but your torque spikes could be higher since your boat weighs more.

302Sport

The Mystics with T55's have seen over 5000 ft/lbs...