Types of Small Vessel / Boat
Diving can take place from virtually any craft provided that getting back on board is easy and safe. The ease of re-entry depends on the freeboard of the boat - the distance from the water to the top of the sides of the boat. The safety depends on the stability - in other words, whether the boarding diver will cause the vessel to keel over dangerously.
There is no hard and fast rule on the type of small boat used for diving although there are some guidelines. The choice lies between the inflatable (inflatable keel, wood reinforced or rigid hulled) and the fibreglass dory. Other vessels such as Rigid Raider Army Assault craft, fibreglass speedboats and small dinghies can be suitable although in certain weather expect reduced seaworthiness.
Most diving groups prefer the inflatable because of its seaworthiness. It has shallow draft, tremendous buoyancy (supplied by the large tubes) even when swamped, and is extremely stable. It allows easy access to the water and minimum effort on re-entry. With a powerful engine and inflatable is a high speed planing craft capable of carrying a full diving team of six to eight and their equipment. A good all rounder is a 4 - 5 meter inflatable fitted with a 40-50 h.p outboard motor. A rigid hulled inflatable boat aka a RIB of similar proportions is also worth considering. A RIB is even more seaworthy and robust, however it is heavier and tougher to launch. An ideal is a 6 meter inflatable with twin 50 h.p outboard motors.
Although there are many very easy and convenient launch sites for boats transported on trailers, there are other sites where the launch spot leaves much to be desired; there a number of awkward spots. A normal inflatable can however be packed away and reassembled at the waters edge aiding the launch process.
The dory is quite popular. It is equally good at planing and is built with fibreglass. Some models have a built-in cabin for shelter. Dories are too heavy to be launched without a trailer and this limits potential launch sites. A good design can be very stable with buoyancy being supplied by a double skin and often built-in tanks, doubling as seats, along its length.
Diving From Small Boats
Many experienced divers prefer to dive from boats rather than from the shore. This tends to be because most dive sites are found further offshore. Diving from small dive boats tends involve deeper depths and the visibility is frequently better. It is much more pleasant to slip into the sea from a boat than scramble across rocks or long walks to the shoreline. It is usually less tiring to fin to the dive site from a boat than from the shore.
The usual approach used when operating from small boats is that the dive takes place in two waves. This is especially valuable when two or more boats are operating as a team. The diving is organised so that the first wave dives, leaving enough experienced divers at the surface man the cover boats. When the first wave has completed its dive and surfaced the second wave kits up and dives, while the first-wave divers take the role of surface-cover party.
All of this organisation presumes the presence and direction of a leader. Usually the coxswain of the boat will fulfil this role. Often he is also the group leader and will direct the diving as well. He may even delegate dive leaders to lead the dives and remain at the surface with the boats watching from the surface.
Launching the dive boat will take preplanning unless the dive crew are experienced and fully familiar with launching and recovery procedures. In less than ideal conditions the need for everyone to be ready at the right time and to work as a team is paramount. During loading the bows (front end) should be held into the sea while loading is taking place. In heavy surf it may be necessary to launch the boat, anchor it beyond the surf zone and swim the items of kit out to it.
Conversation may be difficult during the journey, the noise of some outboard motors can be a loud roar so dive briefings should have been carried out by this point to avoid lengthy waits at the dive site. The coxswain may be wearing a bail-out cord around his ankle. This important piece of kit usually fits into the ignition or engine and will cut the power if a wave throws the coxswain out of the boat. If a coxswain is alone, with no bail-out cord and is washed overboard it could mean he ends up waving the boat goodbye.
After the dive, the boat must be landed and, again, it is necessary to work as a team. With rough surf, it may be necessary to swim the entire heavy equipment ashore before bringing the boat through. Face the vessel into the waves when it is shallow enough for people to enter the water and hold the boat. Teamwork soon moves the mound of equipment back to the vehicles and trailers, provided everyone pulls their weight.
One point to beware of with beach recovery sites is the state of the tide. This will be different for the launching and recovery! If the beach is steeply sloping, it is usually easiest to launch at low tide and recover at high tide. This is not always possible, but the principle ought to borne in mind.
Boat Diving Techniques
There is limited space available in normal small boats for equipment and for kitting up of divers. Consequently, for short boat journeys, it is often convenient for divers to kit up fully ashore before even entering the diving boat. For longer trips, however, this may be inconvenient.
In sheltered conditions, when one boat is anchored as a base, scuba units may be hung in the water around the boat, thus creating more space when moored. Divers then kit up and don scuba units once they enter the water.
Entry into the water is best achieved using a Seated And Backward Roll Entry or SABRE for short. The diver sits on the edge of the boat and ensures that his hoses are not caught, no gear lying about will be pitched into the water by his fins and that none of his equipment is loose. With one hand on his mask and demand valve and the other across his BCD the diver then rolls backwards and then down into the water. The PADI manual describes the effect as kind of exhilarating, which isn't far off the mark to be honest. As per typical diver protocol all divers assemble over or near the shotline, check all is well before descending together.
During the dive at the surface the boat will act as surface cover for the divers, usually all that happens here is that the vessel will at a short distance from the divers (D)SMB / bubbles if neither of these are visible (in rough weather or because the divers are not using one) then the shotline or GPS dive site fix is the next best patrol area. When the divers surface and signal they are ok that is the signal for the pick-up.
Ideally the boat will approach the divers downwind so the divers will be drifting the direction of the prow of the boat. While this is happening some disciplined divers will split into two groups 5 yards apart the boat moves between them in neutral and the divers now on either side of the boat can grab onto grab lines. Weight belts then scuba units are passed aboard, care should be taken with delicates such as recovered objects and cameras, in the process.
Entering the boat is achieved by finning briskly upwards while pulling on the grabline, once aboard stow your equipment and then help any remaining divers aboard. If the boat is too high in the water a boarding ladder may be used, otherwise passengers can assist. Some outboard motors have an engine plate (anti cavitation) which can be used as a foot hold, although make sure the engine is stopped before attempting this!
Seasickness in small boats isn't usually a problem, however, the rolling of a moored boat can aggravate seasickness. When it hits a diver or passenger they will lose efficiency and become withdrawn from the group. If you are prone to seasickness it is very wise to consume an antidote prior to the dive (at least twenty minutes before). Be aware that a common side affect is drowsiness (it can also aggravate narcosis underwater), some canny divers are attuned to the effects and sleep during the journey allowing them to shrug off the drowsiness later as they are refreshed. However this is dependent on the journey time and what duties they may be responsible for on the boat.
The cooling effects of the wind, sea spray and diving should be remembered, hot drinks and waterproof jackets are a good remedy to this. When using a wetsuit a nylon boilersuit worn underneath can be very efficient for increasing cold resistance.
Small Boat Diving - The Final word
Before setting out on any boat trip, leave your route, destination and estimated time of return with your shore party; frequently they can monitor your progress through binoculars from a headland. With a pair of VHF radios much more effective contact can be kept, and possibly a hot meal made ready for your return! It is wise to also notify the Coastguard of your departure and subsequent return.
With forethought it becomes easier to anticipate events and by paying attention to all the minor details it becomes a much more efficient operation. One way of discovering these tricks and also learning how to handle boats in general, is to attend a boat handling course.
Diving from smaller vessels | Diving from larger vessels| Boat Handling| Low Visibility Diving