I am not as experienced as the two who already responded to you. However, I own a 2004 Islander, installed the Lewmar 700 Pro Fish, with the line/rode dropping through the bolt hole where the factory installed lift ring had been located. This hole may be further forward than the other installations discussed above, which would affect the free-fall distance into the locker. The anchor rode is Lewmar's best 1/2 inch 3-strand with 15' of chain. With that said, I cannot get close to 300 feet into the locker. I ordered both the 150 and 300 foot lengths, but do not use the 300' line.
Since it is the last length of line that causes the problem, I sometimes even have difficulty getting all the line in on a relatively shallow anchor.
I have considered whether the problem is that the line may hit and start bunching up on the steel cross-member to which the lift eye bolt was attached. Ocnslr, any thoughts on this as the problem? Does your line drop through that hole or is it centered over the deepest, widest part of the locker? Even though you posted a great picture, it is hard to judge relative position.
Is anyone using the 12 strand brait line that is supposed to lay and flake better than three strand to achieve the posted results?