Helt

Did you add a tunnel tab to stop the porpoise? I have been experimenting with the tunnel tab on my 338 and after talking with Peter @ Skater I should have it neutral with the tunnel or maybe down a bit. I previously had it up and it was planting the ass end off the boat. It really helps the porpoise. I have not tried using it throw the hop when accelerating. The boat rides the best at the century mark. Any information is great as I have very few hours in the boat.

NASCAT

Yes I did add it for that specific purpose.

Neutral w/ the tunnel is basically like having a tunnel extension to a degree because it provides a longer surface for the air exiting the tunnel to provide lift BUT there are no sides so not as efficient as a true tunnel extension or lowering the tunnel tab which restricts the air escaping & creates more lift.

I think the advise you'll receive from most regarding a tunnel tab will be relatively conservative b/c if not monitored & used properly it can be dangerous. I use my indicator to monitor where mines at, only use it when necessary & always raise it prior to entering a turn. I also raise back to neutral once above the century mark or below 65mph where it's not needed.

LAriverratt

so far with the outboards on mine, it hops but not near as much as the 28... the 308 is not quite as responsive to throttle due mostly to the weight i'd think and same scenario on minimizing the hop is turning slightly left or right. I don't have a tunnel tab.

LV

I noticed your turning out, was it set up like that from skater or did you experiment with rotation? Im turning in and thought about trying the other way as well. Does turning out create more stern lift and feel looser?

NASCAT

It's funny b/c what I've experienced is opposite what Bill Pyburn states as being most efficient for Skaters & I hold Bills opinion in high regard b/c IMO he has the most seat, test & tune time of any Skater pleasure boat owner I know of. His comments are in the new 338 thread ( I believe that's on PBN's site)

My boat was originally an IMCO/Bravo boat, 5 blade props spinning in. When upfitted w/ the INDY drives by Skater they spun them both directions but Peter says the 30 or that size range boat prefers out so I received the boat w/ the drives spinning out. Of course I had to to test his theory for myself so we swapped the drives so they'd spin in (way more work than swapping props on a Bravo & running the sticks in reverse only to have to return them to where they were b/c guess what PETE was RIGHT!!) Spinning in provided way too much stern lift & a very loose feeling. Again this is opposite of what Bill states one should experience w/ a Skater w/ less than 800hp / side. I want to believe that prop diameter & drive height also affect the performance & lift of a boat. With that said I returned mine to spinning out b/c it wasn't very comfortable at 90mph on a flat lake w/ no other boats around. Based on my seat of the pants experience I chose not to push my luck. I can run in the 130's comfortably spinning out w/ solid acceleration so I settled for that.

I have wondered if #6's perform different than Arneson's when it comes to rotation since a few newer boats have been built w/ them.

Helt

I have been told not to use it bye some, but after I have used it there is a need for it in certain areas. I have been careful not to have it more than a couple of inches negative. How far do you think I can lower it when going from say 65-100? When you turn are you bring it to neutral or higher? I also notice my tab indicator moving up and down when I have it in the negative in rougher water at say 75. Do you find that normal.
Thanks for all your information.

precisiondetails

NASCAT- yes Bill talks about it in the 388 thread on PBN... I think he also said that the size of boat matters to. Cause I've been told by two top throttle men that on the 388s the out rotation creates stern lift. But you say on your 30 that in created to much stern lift. This is just what I've been told and read. Man this stuff can be tricky.

NASCAT

Helt- Ben Robertson custom fabricated mine. He said never to go more than 30* or 2.5 - 3 on my indicators but I have to be honest I never placed a digital angle finder on my tab at that setting to know what it measures & even then I'd be doing so w/ the boat on the trailer not the way it sits in the water at speed.

My drive & tab indicators are the cableless potentiometer type (sp??), similar to a throttle position sensor (see pic). But to answer your question YES my indicator light will fluctuate between 2 numbers in certain conditions when I'm not really at speed or forcing it to work. Under load it reads pretty steady. My tab rams mounting tubes have some play in them b/c there's a rubber insulating tube within the SS mounting tube / eyelet that the mounting bolt goes thru.

I never run mine above level at any speed b/c I don't think it really alleviates much pressure at that angle & ultimately I don't believe it affects the handling of my boat in a negative fashion in the level position at any speed. I normally don't lower it until I'm upwards of 50mph, just out of habit & my commitment to not over use it or abuse it. Occasionally I do use it to get on plane if I have a full fuel load & 4-5 passengers on board but in reality I don't need it to get on plane. I also don't really trim my drives b/c the boat gets on plane & runs best in the neutral position.

NASCAT

PS- with regard to above level if you imagine that everything from your cavitation plate & above are out of the water at speedso raising the tunnel tab above neutral just seems rather in effective. Get one of your brave buddies & strap him to your hatches to verify this!!

I actually did some nose cone testing for ILMOR so I had some GoPro video of whats going on back there. It's somewhere on youtube. Try searching Mr. NASCAT (i think). Don't get too excited there's a lot of water splashing around back there so no super clear shots. Can't access you tube at work or I'd post it.

Don Johnson

The porpoise on the early 33 Daytona's was standard equipment directly from Eliminator. Eliminator was also kind enough to throw in the added feature of an significant outside lean in turns.