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As a commercial diver, I dealt with a fair number of engineers during my career. The difficulties they had were just grasping the basics of buoyant force mainly. Tertiary educated people that write things down and think that because it works in principle it must work in practice. A couple of examples that spring to mind are that of a civil job laying a railway track under water. The company freighted in a semi load of sleepers for the track to be laid on. We tried to tell them they wouldnt be able to position them. But the engineer responsible was adamant that because they were "so heavy" they would do the job. The crane lowered them into the water and we released the chains and watched as the waves washed them ashore again. On another job, a pipeline tie-in, the new section of pipe was manufactured, (about 100 metres long x 800mm dia) and capped at each end. This was then fitted with hundreds of 200 lt drums for buoyancy and floated into position. The drums were then selectively removed in a calculated manner to provide a controlled descent into position. After the last drums were cut loose this pipeline was still bobbing on the surface like a cork. Even setting moorings. Everybody thinks concrete is great for a mooring because its "so heavy" A m3 of dry concrete weighs almost 2.5 tonne. Problem is it displaces about 1 tonne of water, And it is massive for its weight so it also provides a huge resistance to water currents further undermining its properties as a mooring. A steel plate of maybe 3-400 kg flat on the bottom is far superior to a huge block of concrete.
I could list more that I have personally encountered, and there are dozens more I have heard about, but, its just comes back to people in offices unwilling to listen to experience on the ground.
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