merlinuxo comes pretty close on this one. You'll also have to add in for whatever additional is involved in the peak halyard. Better to bur too much than not enough.
I just bought the boat that your America 18 became, the ComPac Horizon 20, a 2006 model. The 20 part is wishful thinking as the hull is still really an 18. With about 5 hours of sailing her I'm very pleased..