need help with rigging a Yamato 102 on a glen-l Tunnel mite.

[johnsonm50]

The height will most effect speed however the hi-er it is the less leverage is applied to bow lift. The porpoising is controlled by tilt angle. Getting them right at the same time is where youll see a big difference.
The boats being faster tilted out and bouncing is a sign that the motor and prop are trying to break free & run but at what cost to structural integrity?
I think it should be running an inch deep kicked in some then determine tilting in more or not. A balance between fast enough and ability to handle would be great but theres always trade off in my experience.
If your racing a class you can look, ask around and see how the others are performing, when setting up a play boat your guessing more. At present speed trim tabs will help tame it but wont be likely to make it faster, props, set-up & tuning are what will get you to the boats potential speed. It should be able to reach into the 50s unless its real heavy or somethings wrong.
It would seem on a tunnel that the optimal height is variable. to say it rides on the surface at the sponson rear is dependent on enough speed to get it there. If at 45mph it isnt on top then effectivly the props too deep. Id think small changes will help, like raising a 1/4" at a time, and going to slightly less than parallel.. the prop sending thrust down to give some lift to the transome.

[Team B&H]

More engine set-back will eliminate or reduce porpising but remember that you still have a relatively smaller propeller to hold the bow up and steady. We used to run the SST-25 class in OPC with small tunnel boats and versions of the 25XS Merc motors. Speeds got just over 60. I got second at the Nationals running a modified/improved Nardi boat and long shaft 25XS. Del Snyder won with a home made job, short shaft 25XS with trim. Mine floated much better and was easier to launch off the trailer without worry of getting the motor wet. It was fun because they were fairly fast and turned tight really well. The Yamato should accelerate better than our XS motors with fairly close top speeds if you get it optimized and your boat isn't any heavier than ours were.

[seanp3]

[QUOTE=Id think small changes will help, like raising a 1/4" at a time, and going to slightly less than parallel.. the prop sending thrust down to give some lift to the transome.[/QUOTE]

I quarter inch raise with a Yamato is quite a lot. With our setup sometimes just 1/16" can be the difference in cooling or not. Remember to keep an eye on the telltale to see if you're getting water or steam