Tung oil is a great finish. Probably my all time favourite for wood bows. It has superb moisture resistance.
The trick is to cut it with white spirit 50/50 for the first few coats.
Apply a coat, let it sit for an hour or so then rub off any excess.
Use the dilute mix for 3 coats.
Then do as many coats as you can be bothered with of pure oil.
Sunlight, low humidity, air movement and temeprature all affect drying time.
When all is good it takes around 12 hours for a coat to dry properly.