I keep seeing this setup on offshore boats and was wondering what exactly the tubes do going to the end of the drives? Looks like the hard rubber that goes on the thru hull?? Please explain?? I will post pics later..

Allows the props to ventilate, or suck in air, in order to spin up easier/faster. Generally used when running real big props on #6 drives. Once up and running they have no effect on the props, just aid in getting the boat on plane.

Actually newer Fountains with Bravos use a similar device that vents the notch to help the boat break loose when coming on plane.

It really helps when you have blowers as they can spin faster, thus making more boost, more RPMs, faster getting on plane. With big wheels, it lugs the motors until they spin up enough to build boost, ect. Hope this explains.

yep, makes sense now.Was seeing them on the race boats in ocean city and kept trying to figue out what they do.Thanks for the 411... Roger by chance do you have a video of your boat posted on you tube?

Yep, that be me.

You mean that the 700's don't build enough power to spin the 6 blades out of the hole?

No ,,they just accselerate even faster ,,it also has nothing to do with big or small props its because of the high X dimension and these drives are surface drives so they need air to work !!

makes sense