I have no idea what else to call these. The idea is that when the oak gunnels are bolted on at the back end, these plates will be bolted underneath - that's underneath the gunnel iron, with big plate washers, rather than between the oak and the steel. They will then pick up some more planks, the same as the back end planks, extending forward far enough to cover the water tanks. The gunnels themselves will hold these planks in place. That is the theory. I hope that this derbar will be strong enough - if not we will have to fork out and actually buy some steel, whereas this cost hardly anything.
The idea is that the extended boarded area will give us useful space for standing/sitting on, and getting on and off from, and hopefully my bicycle can live there too, chained to the back end rail. It's a bit of a fag hefting it out of the hold every time I want to go lockwheeling (and lifting it back in every time I want to stop) whereas wheeling it on and off a deck should be easy, and I will thus use it more often. Secondly, it will hide the plastic water tanks and make everthing a bit neater, with space to hide other stuff in between them as well. If you can see any hitches with this plan, please do let me know.
Crucially, even if this doesn't prove to be strong enough, nothing will be welded or otherwise irrevocably attached to Chertsey's hull. All must be reversible, shall always be my motto.