T-sar

The areas were 3x8, with no holes, 3x3 blue area in the water, the first screenshot was slabs and the second wasn't. I ended up just spam clicking near the water in a different location and it eventually worked. Once I finish the first boat i'll try again - placing from behind. Thanks for the advice.

I've been trying to place these Rollers for a sailboat but I can't seem to find a valid location. What am I doing wrong? The blue part is in the water, I thought maybe the slabs for my docks might be an issue if it requires full blocks under it so I tried on land and got the same thing. The areas are clear and nothing is blocking the construction area.