Anyone know the approximate tongue weight of a Tracker Tournament V-18.  I bought an adjustable ball mount that has a maximum load of 5,000 lbs and a maximum tongue weight of 500 lbs.  I am wondering if this will do the job?

That is plenty. The tongue weight is depended on where the boat is loaded on the trailer.

When loaded correctly the tongue weight will be 10% of tatal haul

BIll

here's an easy way to find out, and you'll know exactly what the weight is. if you have a bathroom scale (the kind you stand on to see what your weight is) place it on a cement block or some wood, needs to be around the same height as your hitch. place the trailer end on the scale and raise up the jack until it's off the ground. then you can see what it weighs.

Easily!