TUFFboat

Maybe I can say it differently, the first problem is the loose tolerance in the whole assembly. So depending on the rotation you should push or pull the slack out first. Spining 'in', use a ratchet strap from prop shaft to prop shaft to pull the drive tite, then make the measurement. For spining 'out', pull the drives apart and measure. This should get you closer to the real world.
After that, ask yourself 'is the water coming off the back of the boat going straight, or is it actually parting a little to the sides?' If you say yes, than toe in. if not than go straight.
Finally, If the boat is fast enough to FLY and you must 'walk it', than a little toe out will settle it down.

Reckless32

What would you use to pull them apart for the spin out scenario, and do you do this plus measure, with the tiebar connected or disconnected?

BTW if it matters, I'm spinning plain ole stock 28P Bravo 4 blades (outward) if it matters at about 82.5 being the max I've gotten GPS. The Sun boats have a straight V with a small pad for stability, no notch.

TUFFboat

The pushing apart or pulling together must be done with everything assembled ready to go. You are simulating the natural load the complete package will be under while driving. To push apart I use some hi-tech piece of 2x4 cut just a little longer than the space inbetween prop shaft to prop shaft, and one side cut with an angle on it so I can wedge it in.

The amount of toe-in/out after all the loose tolerance is taken out is a "try it and see" thing. In my opinion the water does part as it flows off the back of a Vee , but probably for only a couple of inches. The rest of the water below that is quite stationary. So the lower your drives are, the more they are in the quite water, and there fore I would put the drive more parallel.

You can't beat back-to-back test runs for the truth as it applies to your own boat. ( Why did'nt I just say that at the begining)

Reckless32

I figured it was gonna be a high-tech answer

Thanks for the input. This is one of those things we all talk about numerous times throughout the year and it's interesting how there is not one single consensus (meaning stated most often) approach (meaning step by step) to simply if nothing else, just doing the measurements, much less at what setting apart. That of course is understood to be slightly different with hull designs. IU would like to not only get mine "close" to perfect, but like to someday indoctrnate a novice to the twin world on how to do this should a line up problem arise, versus being just another one amongst many speculative opinions. I think there should be a manual somewhere that actually goes strke by stroke on how to do it like the pros at the factory or F-2 race teams (most similar to stock boats) would approach it through constant repetition.

SHAGNASTY

Well said Reckless!!!

My 2 pennies, I have tried both ways and I really do not see a difference!
Seems to either turn a little to the right or a little left
I'm burning it up in a 1993 19' Infinity, got a closed coolant single 120 Volvo in her

Reckless32

Thanks Shag. Just speaking for the common man....

RaggedEdge

Well I did talk to Fountain yesterday, and they say to set up with 1/16 Toe In, for what it's worth. I started this in an attempt to get the setting from someone who may have gotten the info from the Fountain factory. In reality every manufacturer may have their prefered setting for this, i was trying to find out that info for my boat. Thanks to all that offered up info. My advice to all would be to call your builder and talk to them as to where you should be on this setting.

pstorti

iTrader: (2)

You are good. Perfect set up.

...But if you want to play around and see if you can pick up some MPH try a little less or a little more, but you will have to make the changes and do the runs back to back or the results won't be accurate.

Kanookstr

Ya I plan on marking the tie rod for "O" and 1/8 in both directions. This way I can try it quick in the water.