Im more interested in why your throttle doesnt work.
have you looked at it? taken it apart or tried to fix it? Disconnected the throttle from the engine side and worked the handle to see if it moves the whole distance?
This kind of stuff is basic boat 101, I dont know what you did or who had looked at your problem, but we cant take the attitude like we do with our cars when they break, just call someone, you have to know how to fix things. Or at least try. We need to know more than its broken (not saying you didnt try and fix it) but we are going out to sea in these little boats, just because they have a radio and we have tow service isnt a sub for fixing it ourselves, or like I said at least look at it. How many here actually have tools on their boat?
Im not beating up on you, but reading your stuff it sounds like you didnt try and fix it. A cable can be bought anywhere in the world, a shifter also. Is the linkage to the motor being blocked by something?
How many guys here dont know how to change a tire on their cars? come on be honest, My nephew 33 years old couldnt do it to save his life. We cant treat boats the same way, we need to know, and if we dont we find out by taking things apart and putting them back together, just like the tire on a car, if you dont know how, do it in your driveway before something happens. How many guys here have been stranded in the middle of the lake or sea because they forgot to open the vent to the gas tanks?
people step on our boat and trust their lives to us, having a problem and just hoping it doesnt get any worse without trying to fix it, is not what they had in mind when they came aboard.
To the original question, why would you want to empty the ballast as you drive, what can compare to a 15hp engine on your boat? If its to go faster than fix the cable or shifter or unblock the linkage. If its to empty to trailer the mac will dump its ballast sitting on the trailer before you pull it out of the water. Every inch you drive up it makes it faster to drain. Again not picking on you and maybe the whole story is differant than I see, but at least you helped others when I give you a hard time.....
Mike
) to morrow I have to get out my 
from the Lac Leman to drive home. 
That what the ramp is for. Who cares how the guy waiting to launch rolls his eyes while my ballast is draining down the ramp? I sure don't. And since the plug is out and the valve is open as I enter the ramp, when I get onto the trailer, the water ballast is already starting its journey back to the sea from whence it came. And winching it up does 40% more draining. And the stop at the top of the ramp does the rest.
