Standard amphibious warfare doctrine has the first waves of a beach assault land at high tide. This places the initial ssualt wave close as practical to any beach defenses and minimizes the breadth of open sand to cross to the first covered ground.
In January 1044 Allied intelligence discovered the German intent to heavily fortify the French beaches. previous in 1942-43 the Germans had concentrated their coastal defenses around the ports. Rural beaches were manned only by observation or outposts with some sandbags and a bit of barbed wire. In January Hitler took in Rommels report on the coastal defenses and Rommels recommendation for a heavy fortified beach defense.
As soon as Hilters orders went out to execute Rommels recommendations the French underground reported construction starting and air reconnaissance photos showed the first beach obstacles being emplaced. This of course concerned the Allied leaders, from Montys 21st Army Group staff doing the actual assault planning, to the US and Royal Navies who had to get the Armies to the water line. Everyone began testing methods for clearing the German obstacles. Saturating the obstacles with aircraft bombing on reproductions proved unproductive. Even large numbers of heavy bombs failed to clear lanes through the test sites. The bombardment by heavy cruiser and battleship cannon also failed to clear the test obstacles. The USN even tried ending torpedos into the surf to blow lanes to th high tide line. Which failed. Eventually the decision was made to land at low tide, thus avoiding the obstacles entirely with the boats. The Germans did not place a significant number of barricades beyond the low tide line. boat lanes through he barrier were to be made by engineers landing in the first assault waves. These teams were, while underwire to hand place explosives of the barricades while under fire. Ultimately that worked, tho many teams suffered severe casualties.
One idea suggested but not followed up on, was to turn barges or long pontoon like structures into mega size Bangalore torpedos. Barges loaded with many tons of explosives would be pushed into the obstacle belt, at high tide, then detonated as the boats doing the pushing back off. This was dropped as impractical. It was assumed enemy fire would detonated the kamikaze barges before they were beached. What was unknown at the time is the German defenders had a standing order not to fire on the first wave of landing craft until they reached the far edge of the obstacle belt.
Assuming the US Navy had been crazy enough to try this stunt I have to wonder what the beach defenders would have thought when packages of 20, 40, or 80 tons of explosives started going off 200 or 300 meters from their bunkers :O