Flanking or backing <e1>rudders</e1> are used by <e2>towboats</e2> and other vessels that require a high degree of manoeuvrability.
Flanking or backing rudders
Flanking or backing rudders are used by towboats and other vessels that require a high degree of manoeuvrability.
<triplet> rudders <subject> towboats <object> Component-Whole(e1,e2)