How bad is the Hull?
are their cracks down into the glas?
is it only surface checking?
you said it holds water, but also they used silicon to patch leaks?
Yes I have done some glas work & depending on the job it is time comsumming. Give you a great feel when done though.
if you have cracks you need to grind through them & feather out so as to be able to lay new glas back in with increasing size per layer.at least 1 " bigger per layer.
be careful as tghe heat of summer will set-up your resin very quickly if you get it to hot.
a light layer of resin over any open glas will seal th ewicking off then you can apply the gel coat.
Hope this helps