Ahh that sound like the voice of a teenager
I agree the use of an angle grinder is a bit excessive... apart from the fact that is is not the most appropriate tool....angle grinders perform very poorly on plastics and present un necessary WHS risks.
A hole saw in a battey drill would easily achieve the aims, with less noise and scattered waste material
similarly a simple wood hand saw will do the job very well on a plastic craft.
It may not be law to wear a life jacket in a kayak or canoe...... unless of course you are under 12 then it most certainly is.
But it is required to carry one " Except in river, creek or stream or waters contained within breakwaters or revetments........IF the boat has positive floatation AND grab handles"
so if you have to carry one why not wear it.......not like you are over blessed with storage in a kayak.
don't forget you also should be carrying... suitable bailing equipment, an anchor with 18 meters of cable and drinking water.
cheers