Blowing out water lines

Is it really necessary to blow out the water lines when winterizing when I will be pumping anti-freeze through the system anyway? I don't have easy access to an air compressor so I hope I can get away without it.

As long as you drain first, the small amount of water remaining should not dilute the antifreeze to much.

Thanks for all the great information. It seemed like overkill to blow out the lines. If I had easy access to a compressor I would do it anyway rather than take any chances, but since I don't I'll just make certain everything is well drained and the anti-freeze is at full strength. 

I have the air fitting to blow out lines from another trailer. Does this do the job without using antifreeze? the traps are a different story-will they get damaged in rpod from no antifreeze?

Have used compressed air in our 2011  177 since the winter of 2012 with no problems.  Have done the same as Mr. Halas in that you drain your HW tank by removing the anode, next is to turn your 3 valves to bypass the hot water tank, then blow out the water lines, this takes about 1 minute (to blow out the lines).  Haven't bothered with the low drain points since the first time I did this, they only had about 1/4 teaspoon of water in each.  Finish by using 1 pint total antifreeze in the 2 sink and 1 shower trap.