Picket line rope

["The Craig/Haisz family" <inuvik@magma.ca>]

I would like to be able to put my horse on a sliding picket line at rides. 
I have never used one before, but my horse has. 

I have the hardware required but what is the best kind of rope to use, that
is not too expensive?  What is a useful length?  We have a local marine
store with many types of rope available by the meter. Or there is the
hard-ware store.

Should I attatch him with a neck-rope?  That's all he needs around the
barn.  I have read that you can put a weight at the end of your tie-rope so
the slack slides away from the horse, thus no loop.  Also to put blocks at
any ends near trees, so he does not get caught in tree branches.

Thanks,  Alison Craig