Reduce seasickness
Seasickness happens when the body, inner ear, and eyes all send different signals to the brain, resulting in confusion and queasiness. It is a problem generally attributed to disturbance in the balance system of the inner ear (vestibular) system. Your sensory perception gets out of synch as these nerve fibres attempt to compensate for the unfamiliar motion of the boat moving through water.
If you're not sure you are prone to seasickness, try reading a newspaper while in a moving car. If you have no problem with that, the chances are you should have no problem with boats either.
Seasickness is an awful feeling and has ruined many a diving day. Feeling sea sick can impair safety, for example, you might be so desperate to get underwater you'll skimp on buddy checks, at best you'll be preoccupied, irritable and unable to concentrate.
Don't be caught out. These tips work for most people:
- Consider moving to the stern of the boat. That is where you will encounter the least motion. The bow of the boat pounds through the waves, up and down the stern drags through the water. The ride is much smoother. The boat also rocks from side to side. The higher you are the more movement you encounter.
- Don't look down, or at your equipment for too long - keep eyes on horizon whenever possible. If you do need to work on your equipment raise it, so you don't have to look down.
- Try to stay in the fresh air and take slow deep breaths.
- Avoid reading.
- Prepare your kit as much as possible while in calm water or on land. When actually kitting up make sure the RIB is stable.
- Allow plenty of time to kit up on the boat; do a bit at a time then look at the horizon for a few minutes.
- Don't stand rigid and hang on, bend your knees and ride the waves.
- Avoid hangovers.
- Avoid dehydration.
- Don't go down below decks on a hard boat unless it's essential.
- Keep clear of diesel/2-stroke fumes and other unpleasant smells.
- If other divers are throwing up, don't watch, and/or stand upwind.
- Go easy on greasy breakfast food.
- Keep dry suit neck-seals off your neck until the last minute.
- Be careful with drugs - avoid ones warning of drowsiness and use others with care until you know how they affect you personally. Always try them for the first time when you are not diving to check for unwanted side effects. "Stugeron" (Cinnarizine 15mg) has a good reputation with many seafarers and needs to be taken two hours before sailing.
These drugs can interact with other drugs so get medical advice if you're unsure.
- Get plenty of sleep before the trip.
- Don't eat within a couple of hours of diving.
- Be happy - days with a positive, cheery attitude seem good, feeling glum makes it worse. Avoid post-dive headaches
There are three common causes - CO2 build-up, hangovers and micro bubbles.
- CO2 build up - This is usually due to skip or shallow breathing, smoking before dive, or a high workload. Breathe normally throughout the dive and relax. If symptoms persist, flush the lungs (breathe fully out) a couple of times before the dive, then flush every minute or two throughout the dive.
- Hangovers - Avoid them at all costs and the subsequent dehydration. They will ruin your diving and put you at additional risk. Don't get caught in the 'who can drink the most' or 'stay up the latest' macho games.
- Micro bubbles - This is usually due to bad diving. Dive more defensively - surface well before your maximum bottom time. Watch your ascent rate like a hawk - stay less than 10m/min. don't do yo-yo dive profiles and follow the multi-dive rules (deepest first, 3 max a day, 7th day off.). Pack diving equipment effectively
Pack your equipment in reverse order of donning. Put fins at bottom of bag, you'll need them last and they will protect other equipment when the bag inevitably gets thrown around. Make sure your mask, computer, and any other fragile items are in tough containers. For RIB dives, pack your boat bag for the RIB and then put this inside the main dive bag, this will save time on site. Staying Warm
Getting too cold can spoil your dive and threaten your safety, not only from the hypothermia point of view but cold fingers can cause a loss of dexterity and feeling. Simple tasks such as mask clearing, suit inflation and deploying a delayed SMB can become very difficult. Moreover, it is thought that the body tissues of the skin and extremities will have a reduced off-gassing due to the decreased blood flow. Thus, you will have a higher risk of decompression illness (DCI). It is also well known that being cold increases your air consumption.
A diver's normal body temperature is about 36.9°C, so diving in water colder than that will inevitable mean loosing heat to the surrounding water. At 35.7 o C a diver will start shivering and hypothermia has already set in. Divers should terminate the dive. At 34°C temporary amnesia may occur and between 30-32°C, cardiac irregularities occur and unconsciousness may result.
Most of your body heat is lost through your head and spine. Your internal organs and your central nervous system cannot take the cold. To prevent this, your body will direct blood away from your extremities to your central core including you head and spine. Unlike your internal organs there isn't any muscle or fat insulating your head, hence the need for a hood.
Essentially the options we have are to slow down that heat loss and generate heat internally.
Before the dive
- Avoid caffeine and alcohol drinks; caffeine can restrict the blood flow in the extremities and alcohol increases the blood flow to the skin, resulting in more heat lost.
- Make sure you are adequately fed, rested and hydrated.
- Make sure you stay warm prior to the dive, remember heat loss is gradual and can start long before the dive.
- Wear sufficient layers to keep warm, wear a warm woolen hat and gloves.
- Stay out of the wind where possible.
- Dink hot drinks.
- Find things to do to keep you moving.
- Avoid overheating as this causes sweating and disrupts your fluid balance and diminishing the body's ability to generate heat.
- Keep as dry as possible.
- During the dive
- Try to avoid being cold before your dive.
- Wear sufficient layers of under clothing suitable for the water temperature.
- Wear thick gloves, some divers prefer dry gloves.
- Ensure you are sufficiently weighed to allow sufficient air in your suit.
- Make sure your suit is water tight, remember water conducts heat away 25 times faster than air, so a wet arm or leg will feel the cold fast.
- Keep moving.
- Terminate the dive before getting too cold.
After the dive
- Keep moving.
- Add lots of air to your suit or undo the zip a little to allow air in. This will improve your insulation.
- Keep dry and out of the wind.
- Wear a warm woolen hat and gloves.
- Drink warm drinks. Avoid feeling tired after a dive
This is usually caused by mild hypothermia during the day and/or micro-bubbles from the diving. If headaches are present it is more likely to be the latter. Ensure adequate warmth and defensive diving profiles. Put a 'dive-saver' kit together
It is easy to lose out on a dive through trivial equipment failures. Common problems are:
- Mask strap breaks.
- O-ring blows.
- Torch bulb burns out.
- Fin strap breaks.
- Something seized up.
- Dry suit leaks.
- LP (or HP) hose leaks.
- Regulator adjustment needed.
- Mouth piece splits
Get a small box (like a mask box) and put in the following:
- Mask strap.
- Fin strap.
- Set of o-rings.
- Suit patches.
- Spare bulbs.
- Spare regulator mouthpiece and cable tie.
- Needle and tough polyester thread. Tube of neoprene glue.
- LP port blanking plugs
- Set of hex wrenches.
- Small adjustable spanner.
- Sharp knife.
- Small screwdrivers.
- Variety of cable ties.
- Silicone spray.
For dry-suit leaks, you can now get press-on tyre patches from motor/cycling shops, these you can press on and wait a couple of minutes to make sound temporary fix.
These items should cope with most of the last minute problems and saves the dive. Avoid feeling rushed just before a dive
Experienced divers do lots of little things well before the final dive preparation. Whilst still in the harbour, fill the stab jacket emergency cylinders, configure and test the jacket, cylinder and regulator, loosen straps on jacket and fins and lash it to the bulkhead. Stow your other equipment like weight belt, fins mask and hood in one place near to where you will kit up. Pre de-mist mask. Prepare, check and fit small items to your set, like folding flag, torch, goody bag, DSMB, reel, lifting bag etc. When you are almost ready to dive, all that's left to do is kit up. This helps you avoid feeling stressed, particularly in rough seas, and makes sure nothing is done wrongly in haste. Prevent mask loss
A few precautions can avoid this problem, which could be expensive if it contains prescription lenses. A backward roll off the boat can wash the strap off the back of your head, make sure that you hold it on, along with your regulator. After surfacing, don't put your mask on your forehead as again, a wave can wash it off or you might forget it's there when you remove your hood. Pull it down over chin, it gets in the way a bit, but it's much safer.
Better still, stitch/glue a small strip of Velcro, anchored at one end, to back of hood. Stick the flap over mask strap after fitting the mask. It won't come off so easily and it's much safer underwater too, as the mask can't get kicked off and lost. Avoid shot line crowding
All too frequently divers meet up on the shot line doing deco or safety stops. These can be difficult on a crowded line and there are a couple of alternatives. Firstly, use a DSMB, and deco while drifting or use a Jon line, i.e., fix an SMB line to the shot line at the desired depth, then reel off a few metres to deco. Diving with poor eyesight
Those divers that do wear prescription lenses are often losing something from their experience because of their inability to see all of the underwater life in true focus. Divers need to be able to see well at distance (well, perhaps not so far in the UK) and also close up so you can read gauges and computer.
Prescription lenses, even bifocals are available for most masks and are bonded to the inside of the mask. They are usually made out of glass, although heavier, it is more scratch resistant, and bonds better to the faceplate of the mask. Because diving takes place in sandy environments, you will appreciate the extra scratch resistance. Bear in mind that some low volume masks have the face plate very near to the eye and there may not be sufficient room for the lenses.
Contact Lenses
If you wear contact lenses under your mask for diving, you need to make sure you blink a lot. Excessive starring can cause bubbles to form underneath your lenses and which may cause minor discomfort and temporary blurring of vision. Another risk is that you may loose your contact lenses if you mask floods, this can be prevented by closing your eyes as you clear the mask
Spectacles
Make sure you have a system to protect your prescription glasses during the dive. Many divers place them in their mask boxes and put them somewhere safe that can easily be got after the dive. Estimate the visibility on a dive
Watch to see when the fins of the diver ahead just start to disappear and judge how many other divers would fit between you. Double it and that's about the visibility in metres. Diving in poor visibility
Don't let poor visibility spoil your dive, OK you can't see the wider picture but it will force you to see things in more detail and this can be just as interesting. Follow these tips:
- When descending avoid getting disorientated by descending down a shot line or anchor line.
- Don't hit the bottom as you may stir up the silt and make matters worse, stop a metre or two above it.
- Pause, re-evaluate the situation and let your eyes become adapted to the dark, you may be able to see better than you expected. Try a torch and see if that improves things, remember not to shine it in your buddy's eyes and to shine it on any signals you give.
- Consider using a buddy line, holding hands or using an SMB line to maintain contact with your buddy.
- Avoid kicking up the silt by being neutral buoyant and avoid finning altogether if possible. Some divers can do different fins strokes such as the frog kick that avoid stirring up the silt.
- If getting back to the shot line is important, perhaps due to poor surface visibility, tie a distance line to a point nearby (not to the shot line in case it gets lifted), and reel out with your buddy holding the line. If you reel straight back you will go through any silt you have already kicked up so swim left or right a bit avoid this.
- If you are using compass bearings, believe them. If you think, "That compass can't be right, I've been going in a straight line," ensure there are no inappropriate magnetic influences and that the compass is level and the card is swinging freely. If it is, believe your compass, not your instincts.
- Check your depth gauge and pressure gauge often. It is easy to drift deeper or shallower without visual references, and you'll use air faster than normal if you feel a little anxious.
- If you do become disorientated or you're in zero visibility, close your eyes, relax and breathe easy. Open your eyes every 10 seconds or so to see if it has cleared any.
- If the visibility permits ascend above the silty layer, but avoid being in a position whereby you have no points of reference.
- Limit your movement, settle in one spot and focus on the detail. There's a whole world of violence, hunger, greed, emotion, sex and beauty in a square metre of the seabed. Keep alive the memories of dives
Writing any logbook is good. But as many will testify, it is hard to remember the dive later if you just write "wreck dive, saw lobster". You will get more enjoyment when looking back on your dives by recording your memory hooks. Include pre and post dive events, social events, feelings and atmosphere and what caused them for example, "felt apprehensive due to the darkness and cold", "breath taking view of the wreck on descent" and "scary, drifting so fast", that sort of thing.
Note unusual things like two lobsters fighting, delayed SMB jammed and so on. Jot down unusual events and how you felt and reacted, identify any lessons you learned or things you might do differently next time. These all help to relive the dive. Try a few drawings such as the wreck layout etc. You will enjoy reading these later as the whole dive flashes back into view. One of the best logbooks I'd ever seen contained hundreds of drawings of fish, wrecks etc.
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