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Learning Objective

By the end of this topic, you should be able to answer these question:

Here are the general procedures you follow when entering the water from most dive boats:

1. After your predive safety check, confirm with your buddy and the divemaster/boat crew that you’re ready to enter the water.

2. Check that the entry area is clear of obstacles and other divers.

3. Partially inflate your BCD prior to entry.

4. Use your regulator during the entry. If you’re putting on your scuba unit after you enter, breathe through your snorkel.

5. Hold your mask firmly as you enter (just like you practiced during the PADI Open Water Diver course).

6. After entering, signal that you’re okay (assuming you are).

7. Have your buddy or the crew hand you accessories such as a camera, if any.

8. Move away from the boat/entry area so others can enter. Keep an eye on the boat because it may swing toward you

Chances are you already know the most commonly used boat entries. From small boats, you may perform a sitting back roll (i.e. rolling backward into the water) or a controlled seated entry (easing yourself in from a seated position) off the gunwale. Both entries are appropriate with your scuba on or off.

Chances are you already know the most commonly used boat entries. From small boats, you may perform a sitting back roll (i.e. rolling backward into the water) or a controlled seated entry (easing yourself in from a seated position) off the gunwale. Both entries are appropriate with your scuba on or off.

One thing that separates boat diving from shore diving is that boat diving usually involves descending, ascending and even moving horizontally through the use of various lines. In areas with excellent visibility and little or no current, the only line from the boat may be the mooring/anchor line, which you’re already familiar with. Other areas, such as those with high current, diving may involve using multiple lines as part of your descent and ascents.

Gear lines are lines you use to tie off equipment in the water, usually off the side but sometimes off the transom. They’re common in small boat diving (as previously described), but also used from all sized boats to suspend accessories like a camera for retrieval after you enter the water.

Tag lines (swim lines) may be used from any sized boat while anchored/moored in a current too strong to reasonably swim against at the surface. Tag lines run from the stern to the mooring/anchor line and allow you to pull yourself from the entry area to the mooring/ anchor line. At the stern, the tag line may connect to the transom, or it may continue past the boat and connect to the current line.

Current lines float behind the boat, extending from the stern and terminating in a buoy. This line provides a larger/closer target for divers who accidentally ascend behind the boat (down current), or alongside the boat to one side. In the latter case, the divers swim across the current to reach the current line, which is much easier (and more likely to succeed) than trying to reach the boat.

You also use the current line as a place to wait for your buddy after you enter, and to wait your turn to exit after you come up. When the current is strong enough to require current lines (and tag lines), it’s important to maintain line contact after entering, while descending, ascending and while waiting to exit. This is the only reliable way of being sure you don’t get swept away from the boat and have to be picked up. Current lines are also called trail lines or stern lines.

You don’t see trip lines in most places, and they’re less common than they once were thanks to the increase in moorings. Trip lines attach to the front of an anchor and rise to the surface supported by a buoy. The crew uses it to “trip” or release the anchor because they can pull the anchor backwards with it, unhooking it.

Divers sometimes use trip lines for descent or ascents, but only when there’s little current. You don’t want to pull on a trip line because you can dislodge the anchor, particularly a small one.

Descent lines are vertical weighted lines hanging from the boat, usually from the stern used for descent and ascent references. It usually doesn’t reach all the way to the bottom because the weight will do a lot of damage as the boat swings back and forth on its mooring/anchor. Instead, it usually stops several metres/feet above the bottom.

The biggest difference between a shore diving descent and a boat diving descent is that when you’re shore diving, you commonly start in shallow water and follow the bottom into deeper water. Boat diving, you’re typically already in deeper water.

Most boat diving descents are along the mooring/anchor line, especially in areas with currents. In stronger currents that you can’t reasonably swim against, the procedure is to enter the water next to the tag line (or by the current line in you have to wait for your buddy). Breathing from your regulator, you pull yourself to the mooring/anchor line, and then continue your descent hand-over-hand down it to the bottom, maintaining contact the entire time.

Before descending, orient yourself to the boat’s direction and/or the shoreline based on natural navigation or your compass. Note your air pressure, the time and where your buddy is.

When possible, descend along a line as a reference to provide comfort and orientation. This is especially beneficial if you can’t see the bottom from the surface. If descending along an anchor line, use it only as a visual guide if there’s little or no current because pulling on it could dislodge it. While this is unlikely with a very large anchor, it is possible with a small boat anchor. This isn’t an issue with mooring lines, obviously, nor is a problem when the current is so strong that you must hang onto it as you descend.

When there’s current, there will be plenty of tension holding the anchor in place. As you descend, maintain buddy contact. Watch your depth, time and air pressure. If you’re descending by pulling yourself along a mooring line, watch where you put your hands so you don’t accidentally get any marine life stings. Some mooring lines have extensive marine growth so, as discussed earlier; you may want to wear gloves.

As you approach the bottom, control your buoyancy and avoid contact with anything fragile, such as reef organisms or shipwreck artifacts.

When you reach the bottom, you want to plan your dive so you end your dive at or near the boat. This avoids surface swims, which are more tiring and may present a hazard from boat traffic (use an inflatable signal tube if you must to be seen). When diving in strong current, ascending anywhere but along the mooring/anchor line risks ending up downstream and having to be picked up by the boat.

Most of the time, when you reach the bottom, you swim into the current, which is generally ahead of the boat (the boat may sit at an angle to the current if there’s a strong crosswind). By starting your dive into the current, it helps you rather than fights you on the way back.

Turn the dive and head back with plenty of air and no stop time left. If you reach it with more air or time left than you expected, you can usually finish the dive in the immediate area around the boat before heading up..

At 5 metres/15 feet (plus or minus if there are other divers in front of or behind you), simply stop climbing and hang on for your safety stop.

After the stop, continue up, transfer to the tag line and follow it to the stern. Whether you have a current or not, come up with your arm and hand extended upward, looking up and around. Rotate slowly for a clear view, and watch out for the boat bottom.

Try to break the surface near the boat, which should have a dive flag up. This reduces risk from other boat traffic.

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