I've tried to make an entrance into an underground harbor 2-3 times...I thought that this last time I had the right shape as I had surface mined the top flat, chose a tile that was 2/3 underwater, and mined from the inside out. The tunnel on the right is my latest try at this. Sailboats have no trouble entering, but the knarr gets stuck everytime. I'm not trying to get anything larger than the knarr inside without pushing. I've asked on Freedoma and CA, also looked everywhere---I suspect it has to do with a height check on the tile. Any help would be greatly appreciated.