Training Fundamentals: Diving in a Tidal Region
Currents and tidal movements have always played a crucial role in dive planning. Plan your dive correctly and life is easy. You’ll either drift with the current or find yourself in still waters, able to relax and enjoy your dive. Get it wrong and you may spend your dive fighting water movement or heading in the wrong direction. If you’re diving independently as a buddy team, how do you avoid running into problems? What’s the best way to plan for a day of diving in a tidal region?
Get a local orientation
If you’re new to the area, gather information about the site you’re planning to dive. Contact local dive centers or clubs for advice. Google local dive forums for hints and tips.
If you’re making a shore dive, determine the best entry and exit points for the dive site. Note any local regulations and recommended safety precautions, whether that’s dive flags or permission from the local harbormaster or authorities to enter the water due to boat traffic.
For a boat dive, find out the best place to enter the water and, if required, where you can safely moor your boat while making the dive. In some places, you may need permission to dive a wreck or enter a marine park.
Find the tide times and check conditions
Tides and currents may have a huge impact on your dive. If you’re planning on diving in a tidal region, the strength and speed of the water movement may make diving possible only at certain times of the day.
Books on tide tables are available for most regions, and will give you crucial information on high and low water, as well as the severity of water movement. The cycles of the moon and season will determine whether the tide will be rising and falling more than usual. This information will help you plan the best time to enter and exit the water safely.
If you don’t want to buy a book, check online; lots of websites provide tidal information. However, a host of factors, such as physical obstructions, bays, or bottom topography can influence tides. This makes determining the precise time of a slack tide very difficult in some locations. Always assess conditions before entering the water and don’t rely blindly on tables.
If making a shore dive, the best time to dive is during high-water “slack,” a period of approximately one hour around the turning of the tide when there is minimal water movement. Diving at high-water slack means that the water may be approximately 4 to 6 feet (2 to 3 m) deeper than at low-water slack. In return, the visibility is usually better and there’s less distance to walk getting in and out of the water, as the water level has crept up the beach or shoreline.
Plan your dive for the potential maximum depth and enter as slack water approaches to maximize your dive time. Time and tide wait for no man, as the old saying goes.
Don’t ignore the wind
The wind direction can have a big impact when shore diving in a tidal region. A tidal beach, bay or lagoon can be sheltered or exposed to the wind, creating waves and making entry, exit and visibility more challenging, so check wind conditions. Again, there are various websites such as Windguru and Magic Seaweed that can confirm the area’s wave height, swell and likely time between waves.
Execute your dive
Make a final assessment of conditions before diving in a tidal region. Is the wind strength — and therefore wave height and swell — acceptable for entry and exit? Has the water reached slack? If there are static objects, such as buoys, outcrops or jetties, look for water movement around them. If there is any flotsam on the surface, such as seaweed, is it moving through the water? Its speed will give you clues as to where the water is going. Similarly, are boats moored on a buoy or anchor pointing ‘nose on’ to the wind direction? This is a good sign, because if there was a strong current or tide pulling them beneath the surface, the vessel may float at an angle to the wind.
If conditions are satisfactory, enter the water. Set your dive watch or computer — you have approximately an hour before the tide begins to strengthen again.
During your dive, watch the time and water movement. If you feel the tide beginning to pick up, it’s best to end your dive. Note the movement of particles and life in the water, check the direction fish are facing and, of course, how much effort you’re expending to fin against any current.
Practice basic safety
Plan your dive; dive your plan. Don’t overstay your welcome and have an emergency plan in place. Tell someone on the shore where and when you intend to enter and exit the water, and what to do if you don’t re-appear within set time frames. Take safety equipment. Each diver should have a DSMB and reel and/or a dive flag buoy they can trail on the surface. Make sure you can be seen if you find you’ve misjudged your dive or there’s boat traffic.
A tidal region is not a barrier to diving. With the correct planning, you can overcome its challenges and enjoy a whole new environment.