Hi turboman,
I have had to sand back several of the ribs to line up with the deck boards and also have had to add between 1mm & 2mm to others as they were a little on the narrow side.
The best way is to test with a plank at the fairing stage and any unevenness shows up either as a slight bulge or depression. It is worth checking the whole length of the ribs from the false keel through to the upper deck at this stage, the top section of the ribs can be checked later as the build progresses.
Hope this helps.
Happy building
CMB

Rib 15 is the major headache, so I am going to build up the lower ribs before I start fairing any of the hull. Hopefully then, there wont be as much to sand back, but we will see!!!!

I have been having a good look this morning at the state of the ribs , and I have some higher on the port side than on the starboard side and vice verse . The hull is 100% square and true, Its just how it is!! I suppose if I had fitted the ribs the other way round the outcome would have been different!! So here is my plan of action, it may not be the best solution, but it worked on my Black Pearl and I am happy with that.
All of the ribs that are lower than the deck will be built up with 1x3mm planking until they are slightly proud of the deck. I have measured and re measured the decks and I am happy that they are equal and square. Now for the top of rib 15!!! If you look down the side of all of the rib tops, none of them are level, some are out and some are in. Its just that 15 is worse than the others!!! I am going to wait until I have all the decks before I look into that one, but its gonna need work to get them all the same. They were not cut well at all!!!! I will fit all the decks and then do the same as the bottom, build up and sand back. This is how I am going to sort this, It worked once so why not again!!!!