VS1 outboard set up

[bob horowitz]

Hi Folks,
I just bought a used VS1 with an OS outboard lower and a Dynamite 3660. I'm wondering where the COG should, and where the prop shaft height should be. I'm running a 4S 5000 mah battery and a UL1 ESC. The COG is now about 8" from the rear of the ride surfaces. I have the shaft set at the same height as the bottom of the ride surfaces. The boat ran okay set up this way, very stable, but seemed very wet to me. Probably 1/4 to 1/3 of the ride surface in the water. The only bad behavior was when I tried to turn too sharp. It wanted to hook. Any and all help would be greatly appreciated. I'm kind of new at boating, and this is my first out board tunnel.
Thanks,
Bob

[Darin Jordan]

Hi Folks,
I just bought a used VS1 with an OS outboard lower and a Dynamite 3660. I'm wondering where the COG should, and where the prop shaft height should be. I'm running a 4S 5000 mah battery and a UL1 ESC. The COG is now about 8" from the rear of the ride surfaces. I have the shaft set at the same height as the bottom of the ride surfaces. The boat ran okay set up this way, very stable, but seemed very wet to me. Probably 1/4 to 1/3 of the ride surface in the water. The only bad behavior was when I tried to turn too sharp. It wanted to hook. Any and all help would be greatly appreciated. I'm kind of new at boating, and this is my first out board tunnel.
Thanks,
Bob

Bob,

1) I'm not sure of the exact correct height for the lower unit, but I suspect it's up near .250" or .375" up (to the propshaft centerline). Others here who race VS-1s may know better.

2) I suspect you'll want your CG back closer to 7.5". Every boat is different, but I believe that's where people run it on these boats. However, when you RAISE you lower unit, it'll also raise the sponson tips, so do that first, then reevaluate your CG.

3) Hooking: If you still have this issue after the other two issues are resolved, SLOW you steering rate down. It's likely too fast, and tunnels have to be driven SMOOTHLY, with gentle steering transitions. Quick steering outboards will do evil things.

Remember, you fly down the straights, but when you want to turn, you need to ease GENTLY off the throttle JUST enough to set the tips down on the water, then start it turning, then feed in more throttle as you transitions through the turn. Very few setups will be able to run WOT INTO the turn and hold it without flipping or hooking or simply sliding the nose out.

[Brandon Galles]

Prop should be even with the bottom of the sponsons

[Darin Jordan]

Prop should be even with the bottom of the sponsons

This is not correct...

[Brandon Galles]

This is not correct...

Please elaborate - everything I've always bee told and have used has been with this methodology. tunnelsetup.jpg

[bob horowitz]

Guys,
Thanks for your input. I'll be trying these changes Thursday or on the weekend. I'll keep you all posted with the results.
Thanks,
Bob

[Darin Jordan]

Please elaborate - everything I've always bee told and have used has been with this methodology. [ATTACH=CONFIG]146592[/ATTACH]

First, "prop should be even with the bottom of the sponsons"... Top of prop? Bottom? Middle"? Way to general.

Your diagram is a good starting point, but at least has the correct measurement reference.

Where this point will be is completely dependent on the hull/tunnel design, as well as on prop design, diameter, etc.. Your diagram is a good basic starting point, however.

The centerline of the prop on my M11 Dragon is a good 0.250" up from the bottom of the ride surfaces. My Lynx is up there as well.

[Brandon Galles]

Huh, I'll have to give that a try and see if I can get some gains. Always good to hear/see others setups. I've always run my VS1 & ML PX335 props right at the center line with pretty good results. Kind of assumed if I got any higher I would begin to induce cavitation.

[properchopper]

I'd give Darin's input some credence - He seems to have a tad bit 'o experience to back it up

https://www.youtube.com/watch?v=4mW7B4yg7KM

[bob horowitz]

I can't wait to make these changes and run my boat again. I really get excited over the incremental changes and gains or losses. It's kind like my job, you build a new machine and then you tune and tune to optimize it's performance. They almost never work 100% at the first running.
Thanks again for all the help,
Bob