battries ?

[sidelock]

Putting two AGM battries in the front fishbox of an 18 ' SF. for a 24v electric trolling motor & they will be in individual battery boxes . Should they be tied/strapped down to the hull ? The only surface a tie down strap could be atached to is the fishbox liner & it would have to be self tapping screws since there is no access to get nuts on the end of machine screws.