Da Vinci was said to have designed modern inventions centuries before they were actually invented. What particular inventions were these?

Calculator, Double Hull, Solar Power

Also tanks and theory of plate tectonics

Amongst many others, the parachute and the principle of the helicopter. Any well educated person studying his "diaries" , will be blown out of the water by his observational power/perceptions, keen sense of deduction, on topics that span a range that is almost impossible to comprehend. It is important to study his writings DIRECTLY, and not to rely on 2nd (or 3rd/4th) hand citations.