So whats it made from?

The skirt fixings need to be stronger than the tear strength of the fabric otherwise the fixings will tear out before the skirt (bad news if its an underhull fixing).  Underhull fixings should ideally be bolt through and top hull fixings self tappers (or something else that will give out before the underhull fixings do).

thanks both.
the hull is not made of GRP, there is nothing to screw to

Welder Link


Decent roller link

Welding a skirt link


Fitting a skirt link  - if a new craft then fit the skirt before anything else - makes it easy to tip the hull.

The skirt should be attached using screws (every 100-120mm) through clamp strips - gluing to the hull won't be strong enough (you can also glue to reduce leakage and/or hold it in place for the clamp - Evostick or any contact glue will work for that).

Look on Ali Express, plenty of PVC welders on there for under £100, some below £50

cannot weld onto what i am building, i need to glue the skirt attachment a the very least, which is PVC to PVC.
unless i am missing something, fabric welders are extremely expensive. 

Glue isn't recommended - get a welder, its cheaper than buying glue.

whats the best skirt glue to buy for a PVC bag skirt?
I have a 15year old tin of gripsotite PTA plus, which has gone a bit milky, still sticks the kids school shoes back together, but probably will not use it on my craft.
is there anything that people recommend, or shall i buy a new tin of PTA.
thanks jon