The Danforth was designed to pull-off landing craft from a beach after dropping off troops under fire. It had to set under way in situations that involved life and death.

Of course, the Danforth might not do so well in kelp if you're moving too fast -- but then you have to balance the issues of size and weight.

The Fortress -- for the weight has tremendous holding power; however, it's ability to set at any velocity is more complicated by it's relative lack of weight vs. it's "wing" effect. (I believe that its flukes that work when buried, make a great wing if you pull it with some speed.)