Spinnaker repair tape works well for comparatively small tears in wing canopies.
For mono it is definitely the wrong stuff and without having tried I wouldn't trust it for dacron in windsurfing sail, where forces are bigger and cloth s a lot heavier (might work though).
As has been mentioned, mylar repair tape can be used to fiy mono. If you hvaen't got any, stickers (brand or shop merch) works better than duct tape). A bit of soapy water can help you to place stickers perfectly without air bubbles.
