48 minutes
The no-decompression limit at 18 meters is 48 minutes and that will take you to pressure group S. This information can be found in any Table or wheel RDP (recreational diving planner) and it is basic. If you do not know how to use this table, you shouldn't really be diving. If you are in a course, then you will have a lot of time to practice. Dont forget to dive well within your no decompression limit. Live on the edge, Dive safe.
18 meters ≈ 19.6850394 yards 18 meters ≈ 59.0551181 feet 18 meters ≈ 0.0111846815 miles 18 meters = 1800 centimeters 18 meters = 0.018 kilometers
18 x 11 feet = about 18.4 square meters.
18 feet = 5.49 meters.
18 meters = 59.05 feet.
18 feet is 5.4864 meters (says google, just type "18 feet in meters") 20 feet is 6.09600 meters 5.4864 * 6.09600 = 33.4450944 meters squared (AKA square meters).
18 square meters is the same as 193.75 square feet.
18 square meters = 193.75 square feet.
Less. 18 meters is 59 feet.
18 feet = 5.49 meters.
NoD limit for 18m (or 60ft) is 60 minutes. Anything past 60 minutes you will owe decompression. Thats if you have enough air to be at that depth for that long.
18 meters is 59.05 feet.