In the photo of the riveting tools at the top of the page, the rove iron is above the holding iron and just below the folding 2-foot rule. A rove iron is one of those tools that isn't needed all the time, but when it is needed, you'll be hard pressed to work without it. Looking like an oversized punch, it is correctly a rove or burr set.
There are always places in a boat where a holding iron simply won't fit. That's where this tool comes in. It is just the ticket for setting roves or undersized burrs, and particularly handy for squaring the inboard ends of rivets at the turn of the bilge so that they can be peened properly.
That's a bigger deal than you might think. To explain: For maximum bearing (and therefore strength), the rove or burr of a lap or rib rivet has to sit flat on the surface of the wood. If the nail to be riveted protrudes from the surface at an angle, as it is apt to do, the only way to square it is to bend the inboard end of the nail so that it is perpendicular to the surface. There's nothing to it. Just slide on the rove iron and straighten the nail. It's simple enough, but it makes a considerable difference in the strength and appearance of your boat.
You will also find that a rove iron serves admirably for pushing burrs over the ends of rivets with sloppy points (which are getting to be the rule rather than the exception). Made of hot rolled steel, it measures approximately 6" long and 3/4" in diameter, so makes a great heavy duty nail set as well. These days we turn them from 3/4" hexagonal stock so they won't roll out of reach while you're working. Here's what they look like: