My rope that is used to connect from the stern to the tow line on one end is un-knoted from the carabiner, any info on how the thread the rope back through it self? or just use a knot?
The line you're talking about....is it the polypropelyne weave?
If it is, get a plastic fid, make the size eye you want, tie a loose overhand knot,then run the fid thru the core of the weave. finish by snugging the overhand knot down to the spot where the line goes into the core.
Also, the carabiners are (imo) junk, get good snap hooks.