Under coding regs for daylight ops if MCA coding, life jackets have to be carried aboard with a 10% extra spares.
The fact that most of us won't allow persons aboard trips/ charters without wearing a life jacket at all times, unfortunately this method of carry is "within" rules. Explain this to MAIB enquiry should something awful happen. The time you need a life jacket is immediately you enter the water, not here is one please now try and put it on and use it,
My colleague at Southsea exhilaration rib rides who does similar to this operator of short blasts also insists on LJ,s so time is not the issue