ICR lazy day cruise

We wan't to go on the ICR lazy day cruise this year, except we have a small problem. My eldest daughter has not got a very good pair of sea legs and the thought of spending all day on a boat slightly disturbs her. Does anybody know what size boat we would be going on? Any photo's would be good............and no funny ones like pictures of the titanic please.
We went whale & dolphin watching of the coast of lanzarote a few years back on a smallish catamaran and it got a little choppy out there, she didn't enjoy it one bit. We have told her it would't be like that as does'nt go right out to sea, but she still needs to be convinced. 



