Help roof cover leaking

[Julian]

hi im new to this forum so hope someone will be able to help,

I bought a 18 foot yurt (cotton canvas) last year to hire out but since then I've had nothing but problems with the roof cover, there are a few faults 1 - is they seem to have used a needle too big for the thread (only in places) 2 - the roof cover seems to be quite lose on the frame (only towards the bottom) so when it rains it tends to hold water in a couple of places between the roof poles (either side of the door and a bit around the back mainly) and 3 - the seam going around the bottom of the roof cover seems to be quite high so the rain tends to run down and hit the stitching before it can run off the cover

In an ideal world i would just make a new roof cover but funds are very tight at the minute and cant afford a roll of canvas

Ive tried reproofing it with nikwax cotton proof but still having problems

My only possible solution at the moment that i can think of would be to (cut) open up the canvas and add another triangular segment and refit the cover to allow the bottom seam to drop down lower so the rain can run off before it hits the stitching, add some taps at the bottom of roof cover maybe 8- 10 taps spread around the roof cover so I'm able to tie it down to the ground and pull the whole cover down tighter, and then finally maybe reproof again with a stronger solution

Sorry quite hard to explain in words but as i said new to this forum so not sure how to upload pics yet but will do so as soon as i work it out lol

But any ideas would be greatly appreciated
Thanks julian