Place cedar planks into a roasting pan big enough to easily fit the planks. Add water to cover the cedar planks completely and place something on top of the planks to keep it submerged.
Soak cedar planks in water for 1-2 hours.
Start preparing the coals and grill about 20 minutes before you’re ready to cook.
Peel and devein shrimp if needed. Place shrimp in a bowl and mix it with sugar, lime juice, pressed garlic, and salt.
Place soaked cedar planks on the grill and leave them for about 10 minutes to heat through.
Drain off excess liquid off the shrimp and place shrimp on the hot cedar planks, try not to overcrowd them.
Close the grill lid and let it cook. Smaller shrimp will take about 4 minutes on each side and jumbo shrimp will take about 6 minutes on each side. Try not to open the grill lid too much besides flipping the shrimp. Shrimp are done when pink and completely opaque.