Originally Posted by Gray
'coz they wouldn't be fixed in position and would therefore move right in against the engine causing the rope to rib against the engine and more likely to drop down closer to the prop when at slow speed.
I'd be tempted to try it first, as the rope will be so tight whilst towing it may not move.
Even if it does move, something very subtle like a few wraps of tape around the box will be enough to stop it moving inwards once its tight.
That way the only thing left on the boat when not towing is two bands of tape around the box section.