Ya know there is actually one very easily adaptable off the shelf, or outa the bone yard (good) planetary option out there. The Gear Vendors OD is an 0.78:1 vertex (cone) Raybestos clutch system proven to hold 2k hp. Doug Nash is the original design, first released in Corvette's, and later on Dodge 1/2 pickups early 90's.

While the GV has been improved a little, for testing purposes the DN are not hard to find. Dimensions are identical. The pro's, it's shift-able. Down side, +12" min..

Ditto on the GearVendors OD. They've been run in Dragweek for many years and have proven to take crazy HP/TQ abuse. Just a possible OTC option.

I talked to gear vendors a few days ago, and they said there is no way there overdrive would work. It will handle the power for short amounts of time but they said that everyone that has tried one in a boat with half the power I have has broke it in a few min even with external oil cooling ect. There is something about the small gear needle bearings that they cannot cool or oil good.

On my two speed transmission we were having problems with the planetary needle bearings so I drilled little holes between some of the teeth into the needle bearings in the small planetary gear and every time the teeth came around with oil on them and meshed with the other gear it would squish the oil into the needle bearings and I never had a problem with them again. But they would not handle full power for more then a few min even with the modification. The first gear in mine was only designed to let the turbos spool up to get on plane and then shift into high.

The JJ48 conquest boat had a similar transmission/gearbox that used quick change gear sets. You should discuss with Rich Luhrs (T2x).

Ernie

For these reasons this is why I ditched the #6s on my diesel build and went with Arnesons and overdrive in the albeit slightly heavier (200 lbs) transmission.
This is a much more bullet proof approach as the gearboxes are rated in excess of 1600 lbs and the drives will see less torque as the drive input speed is greater than the engine output speed.

Probably a good time to review the gearbox/overdrive/drive setup again.
My recommendation would be either a multi-speed gearbox with OD on the back of the Cummins driving #8s or an SCS dropbox with interchangeable gears and run Arneson thrust tubes, either of these will give you a proven reliable solution.

A couple of options, SCS or Arneson

When you add power,run out of pitch just change the gears!

Hi Tyson,

Have you talked to Weissmann about a possible solution?

OR

We just spent six months of work and probably $100,000 to go from the arnesons to mercury number 8's, I'm not quite ready to go back the other direction... yet.

Instead of modifying Mercury M8s, or trying to make the Arnesons work, or wasting time on an overdrive transmission, run the boat like it is, the gear ratio should be about right when you are loaded heavy anyways

While enjoying the boat for a while work on inventing your own out drive that's better than the Arnesons, M8, Wiesmann, and X-power!

Tyson,
If your designing it anyways, any reason the gear box can't be on the outside of the boat?
Basically have it take the place of an extension box,... then leave your engines where they are...


Jon