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Test props turning out and shutting down throttles.

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Old 02-22-2002, 10:05 AM
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Uncle Toys
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Default Tested props turning out and shutting down throttles.

I realize with TooOlds daughter posting pictures all over the board, nobody cares. But I thought I would follow up the discussion from a previous thread, "HTM Mishap."

I had Eliminator switch the props so they are turning out (thanks Ron P for turning me on to T2x's thread - awesome!). Bob Leach looked pretty disappointed when I told him, said I would loose 5 mph off the top end. Best I could tell, I lost 4 mph (same weight, gas, temperature). But boy oh boy did I make up for it in handling. With the props turning in, I could barely get the thing to turn above 65 mph. With them turning out, I was carving U-turns up to 70 mph and course corrections at top speed (77 mph, still had the 26" props which limit me to 4,400 rpm). The really cool part was anything over 50 mph the boat was leaning in on the turns! I really liked that. The leaning out thing with the props turning in was spooky!

Considering how few boats where on the lake and how calm it was, I went ahead and tested shutting down an engine at different speeds. I couldn't have been more pleased with the results. All the way up to 70 mph, either side, the reaction to quickly shutting the throttle down was mild. In fact, on the last day, I shut them down while my hand was off the wheel. The boat started to turn to the dead side, but it was mild. I did the no touch trial up to 60 mph (at which point I ran out of balls - not the boats fault).

Boats back at Eliminator so they can finish the tunnel modifications. Hopefully, I'll have the 27" props next time. Plan on continuing the test to higher speeds as long as the reaction stays mild. Not really excited about being a test pilot, but I think its important to know. If any of you have experience with this, I would love to hear it!

Last edited by Uncle Toys; 02-22-2002 at 10:41 AM.
 
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Old 02-22-2002, 10:17 AM
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Uncle Toys, I am really glad to hear your results with switching the props around.

I wonder if Eliminator chose to spin them in or if they don't think it makes a difference so however the drives go on is OK by them.

It sounds like you can now relate to how poorly a cat can handle if the props are spinning in. Could this be what happened to the HTM?

How did the boys at Eliminator react when you explain the rotation theory to them?

Leaning into a turn in a cat really kicks ass! I'll give up a few mph too if I could make it so the boat didn't scare that **** out of me every time I turned the wheel.
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Old 02-22-2002, 10:22 AM
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Take a look at the photo under my name. This is what happened the one and only time to ran a race with the props spinning in.

Two bad it was the second race in the Worlds in Key West.
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Old 02-22-2002, 10:40 AM
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Ron P - I'm with you on giving up the speed for the leaning in. That was totally "kick ass." It will be interesting to see how it handles in choppy water. All I can find this time of year is glass. Haven't had a chance to tell the Eliminator guys yet. We are going to stop by there tomorrow on our way out to see Cattitude's jeep competition. If I get a chance I will discuss it with them, but damn they are busy right now. Considering this is their first twin 26' Daytona, they couldn't know one way or the other. They probably just went on experience from the 28' Daytona.
 
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Old 02-22-2002, 10:44 AM
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Unc,
Glad to hear your results were positive, I have also found that the handling on both of our cats was best spinning out. Spinning in didn’t show any better speed on both the 28’ and 32” Skater. We did the swap “In vs. out” on the same day, a few hours apart. The both boats turn like they are on rails, the lean is to the inside of the turn not the outside, and If you get out of shape, one sponson going up, the other one going down, jumping on the power will force the high side down. I think you might find the 4 MPH difference might not really be there. Run the boat, trim for top speed, record the GPS MPH, come in and swap the props and go back out, and check your speed. I think you will find the boat will run better in the rough also, Spinning "out" tends to hold the stern down, and allows the bows to pivot up and over the waves easier.
Philip

Last edited by Philip; 02-22-2002 at 05:54 PM.
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Old 02-22-2002, 12:33 PM
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Thanks Philip! Funny you mentioned the speed difference might not really be there. The first day out I though I registered a top speed only 1 mph under the top speed with the props turning in. But I had forgotten to reset the "max speed" setting, so I wasn't sure. I've heard that the cats will run better in the rough, can't wait to try it. This time of the year it's tough to find - not enough boats out to chop up the lake.
 
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Old 02-22-2002, 01:13 PM
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Very interesting! This kind of thread is going to turn some skeptical "V" hullers into cat buyers!
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Old 02-22-2002, 01:27 PM
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U Ts,
I have broken vertical shafts on my outboards (TWICE ) at around 85MPH each time and like you said there is only a slight pull to that side, I think it would be worse if the prop locked up but have no idea how much.

At Havasu Sept 2000 had a pinion nut back off and jam the pinion gear but was pulling back the throttles at the time probably doing 55-60 and that prop locked, really didn't skew the boat as much as I thought it would, but I'm running with cleavers and high propshaft heights.

Caleb
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Old 02-22-2002, 04:15 PM
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Thanks Timewrap, appreciate the input
 
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Old 02-22-2002, 05:38 PM
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I love it! Aint it amazing when the FACTS are on your side?

T2x

PS: U T try changing prop heights....spinning out doesn't like the same water as spinning in...... also (sigh).....prop shafts should be 3 1/2 inches outboard of the tunnel wall. See ya!

Last edited by T2x; 02-22-2002 at 05:42 PM.
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