I used 3/4″ stainless screws. Don’t know the number but they are a solid diameter. There was about 1/8″ or so of aluminum and roughly 3/4″ wood to screw into. With the flush mount the pressure is not a direct pull, no fish will pull it out. Maybe if you tied an anchor to it you’d have a problem. I do check them once in a while but have rarely had any loosen. No doubt bolts will be better but screws appear to be plenty strong.