I have a 98 Alumacraft Lunker LTD V-16 which I leave in the water at my dock all summer.  My Uncle told me I should put some car wax on the hull to help keep it cleaner longer.  Will this damage or have any adverse affects on the aluminum at all?  

 

I also have a Yamaha F25 tiller manual start (175lbs) on the transom which has the C-clamps mounts on it.  I only used the C-clamps last year and did not bolt the motor to the transom.  (My thought behind this is that I did not want to put any more holes in my transom than necessary)  The motor did get "loose" once when I tried a hard turn at high speed, which worried me, but I now know that I can not turn very hard at high speeds.  Should I just mount the motor with stainless steel bolts to avoid loosing the motor?  If so which sealer should use?  And could mounting "tear" up my transom?

 

 

 

If it's a painted hull the wax is fine. If not, look up Sharkhide. They sell a cleaner and a sealer which should accomplish what you want.

I'll look Into sharkhide since it is not painted. Thanks!

The motor shouldn't loosen up. If you tighten it down and then lock the handles together or put a locking bar on it it shouldn't loosen up. If you still have an issue with it gripping, just go ahead and mount it. Use stainless bolts and be sure to seal the holes with marine grade silicone. 

For safety reasons a 25hp should be bolted onto the transom. The pressure clamps are enough to hold the motor onto the boat and in place when on dry land, but once out on the water if you do any sharp turning the motor could slide around and be a real problem as you stated. Been there, done that.

 

My motor has a 4 bolt pattern, but two of the bolt holes are in a location that are unusable, but the other two I drilled out and bolted as described above and have not had any problems since.