okay so I bought the hand winch "crank" strap for my trailer to secure the boat to the trailer. my buddy says the only real way it will work is if I attach it to my trailer with a vertical "post"......but the thing isn't sold with the vertical arm....so my question is do I really need this? and if I do what am I searching for? I have a 14' aluminum jon boat....its not heavy and I run 3 come-alongs across it also....thanks in advance