Thanks a lot. First of all my apologies for forgetting that I've already written in december another post with the same introduction, now I've reminded it and fonud it, it was about the inner inserts idea (abandoned until I'll try the board as it is)
Then now I realize that the long box is the way of building it in the strongest way as it is bonded to the deck as you say.
Thanks for the suggestion so now I/m thinking the bast way to move forward the holes, I think that with a lot of care I can do directly new holes, as they are really way back than the correct position, 4-5 mm.
I plan to screw on the head of the stock dt fin some long M6 screw without head, put the fin in the box and check with a caliber from the existing holes how far is the right position, then to make there the correct hole.
Therefore to add some good epoxy resin and seal the old holes and the edges of the new ones.
Two other small questions. What is the lenght, head included and/or without it, of the recommended screws for TT and DT fins with the F158? I can't find the spces , clearly after all these years they were erased, I suppose.
Second: on the pdf image the F158 drawing has two inserts for the chicken strap or central rear strap, but mine has only one, was at the end built to use the front fin screw for rear footstrap screw or something else?