I had one of those with another F18 on the same day (I think) - I was on port running a little deep to get to the left mark (left as I was approaching). The F18 was overstood and coming in with speed at a relatively sharp angle with some speed. The left mark was very favored with the wind and I, assuming he was going to round the left mark, left him room to round. Thinking about it though, if he had intended to go to the right mark, I would have fouled him. As it was, he gybed around the mark inside me and turned head to wind right into it (I think he had his mind set that the wind would be square with the course). I had setup to be on his sterns hoping he was going to round deep leaving me a window but had to duck him while he played with the mark. After first saying he would do a penalty turn, he later complained that I didn't leave him enough room. I asked my crew to just remember where his rudder casting was when I started my bear away to avoid him (it was at my bow / forestay bridle) as evidence that he was actually clear ahead at the moment he turned up into the mark. I lost track of him and can't say whether or not he did his turn.

I remember there was a reason that the marks were to be placed so that the "boat-lengths zones" didn't overlap - it made the rules much clearer. I'm not sure that's the case anymore (I need to read up).