Can vest/jacket scratch HR sensor?

Hi,

I have got a F5 and use a chest strap for outdoor sports like running. I would like to wear the watch over my vest (out of training material/polyester, wrist is a little bit raw, from Adidas) or over my jacket (waterproof light wind jacket from McKinley).. Now to my question: Would it damage/scratch the optical HR sensor of the watch when I wear the watch over the vest/jacket sometimes? Or won't it matter? How is your experience? I don't need the optical wrist HR sensor when running as I use the chest strap.

Thanks! BR,
Bernhard