The plans for the S11s arrived today and I have been going over them. The sloop rig calls for a deck-stepped mast and shrouds. I am wondering if I can replace it with a keel-stepped free-standing mast like the cat-rigged version. I understand that I will have to build sealed tubes or forgo having a sealed front seat since the mast steps are on top of the front seat. Also the seat will have to be reinforced side-to-side (athwart-ship?) I am more interested in if there is a structural reason for not having a free-standing rig, at least for the "optional cat rig" position. Thanks.