Sunday, August 25, 2013

How to tie on a bolt snap

How to properly tie a bolt snap for scuba diving.

primary hose with attached bolt snap
Attaching a bolt snap to your gear is something most divers need to do from time to time, whether it is to a back-up light or to a pressure gauge, and if you are a DIR diver you'll be attaching a lot of them.  Here is a breakdown of how to do it correctly.

When tying a snap on we use #24 braided nylon cave line.  Nylon line is durable,  lasts an incredibly long time, is cheap to replace, and odds are you will always have some on hand to do so.

To attach a bolt snap, the only knots we will really be tying is a simple reef, or square knot.  and a "half knot".

For demonstration here, I'll use a larger diameter rope to attach a bolt snap to a wooden dowel.  step one is to loop your line through the bolt snap three times.  No knots yet, we are just winding the line around the dowel and through the snap.

step 1step 1step 1

step 2Next we will tie two knots to secure the bolt snap in place.  The first will be a half knot.  You will want to put some tension on the line to tighten the loop you made around the dowel.  While keeping the tension, tie the half knot.

Step 3 is to tie the final reef knot on the opposite side of the bolt snap.  you will need to pull the ends of your line under the bottom of the snap and the loops holding it to the dowel.

step 3step 3

Pull the ends of your line to ensure everything is snug and seated where you want it, then finish your reef knot.

step 3step 3

With your knot in place, the last step is to cut the excess line and melt the knot with a lighter.  Nylon is essentially made of plastic, and melts easily.  Doing so ensures the knot will never loosen or fray.

Here is the finished product on my primary hose.

attached botlt snap

Armed with this knowledge you can now put a snap anywhere you need.  For some advice on what types of bolt snaps to use, check my post on bolt snap selection.  Good luck, and dive safe.

Saturday, August 17, 2013

Scuba fins: split or paddle?

Scuba Fins and are generally the first piece of equipment a new diver will buy.

This purchase is usually made before the diver has ever entered the water, making it difficult to make and informed decision on what type of fin you'll need.

Dive shops advocate split fins these days, and claim they require less effort while diving, and while this is a true statement, in practice a diver will expend more energy diving a split fin over the course of a dive.

Here's the science:

A split fin is designed to do one thing very well, and that is high-speed flutter kicking.  The split causes a propeller-like action, the pressure differential generated moves the diver forward with less effort (see Bernoulli's Principle).  The trick is, while diving, a high-speed flutter kick is generally not the best kick to use.  If you are trucking along at full speed the amount of energy you are expending and gas you are breathing (even with split fins) is excessive.  You will tire quickly and not have an enjoyable dive.
paddle fin

Scuba is a slow sport. Remaining still, or using a slow speed kick is the goal.  Exploring a coral reef is not done at 90 mph, and diving in advanced, overhead environments requires precision and power on demand, not marathon speed.  Here is where the split fins weaknesses become apparent.  The split itself reduces the power the fins can generate from full stop.  This makes turning and pivoting in the water more difficult.

Frog kicks, excellent for letting a diver rest, and required for any type of technical diving, are of little worth in a split fin.  The limited initial power of a split fin does not allow for good propulsion from a frog kick.

Back kicks, essentially a backwards frog kick, are equally crippled by split fins, causing a diver to work twice as hard to reverse through the water.

The full flutter is also the kick most often responsible  for silting up dive sites, quickly dropping the visibility for surrounding divers.  The repeated strong downward motion of the kick propels water towards the seafloor causing the silt to disperse in the water.  If you've ever been in a crowded swim-though, you've likely had this experience.  To use any other means of propulsion, a traditional paddle fin is ideal.

A Modified Flutter Kick accomplishes a similar strong forward propulsion of the full flutter, but aims the fins upward, preventing the diver from disturbing the silty bottom.

If you are interested in a pair of paddle fins, it turns out the design was perfected some 50 years ago.  The Scubapro Jet Fin is the de facto standard, and with good reason.  They deliver excellent thrust, and set of these solid rubber fins will likely outlive you.

Tuesday, August 13, 2013

Onsite scuba gear repair, and the importance of a save-a-dive kit

The adage "Be prepared" is true of most things in life, but doubly so when scuba diving.  

Scuba equipment is life-support equipment after all, and the importance of regular maintenance is paramount.  But, even with proper care, unexpected failures can still occur.

Everyone knows they should carry a "save-a-dive" kit, but like buckling a seat belt, often the simplest safety procedures can sometimes seem like too much trouble.  A commercial save-a-dive kit is an excellent step on the road to preparedness, since a simple o-ring can make the difference between executing a dive or not.

Generally these kits contain the bare necessities, (assorted o-rings, a mask strap, a mouthpiece, etc)) and I recommend divers carry these items, but failures can occur on any piece of scuba gear, and having a spare for any circumstance is invaluable.  This is by no means an exhaustive list (I see divers that advocate carrying a spare set of fins) but it is what I take to every dive site, and it does not require a steamer trunk to hold all of its components.

Everything listed below fits easily into a small duffle bag.  In fact its primary compartment carries 2 canister lights, and does so handily with all of my spare parts in tow.
save-a-dive kit
A well stocked save-a-dive kit
Armed with these items you'll be prepared for most scuba gear breaks and won't have to scrub the dive plan.  This list of equipment may sound a bit excessive to a new diver, or understocked to a boat captain, and I'd encourage you to find what works for your needs, your style of diving, and the type of gear you own.  I can tell you from experience, something only needs to break once for a spare to become a mandatory component of your kit, so better to over prepare now then find yourself lost in your time of need.

Sunday, August 11, 2013

Why dive a backplate and wing instead of a jacket BCD

The backplate and wing, possibly the best piece of scuba gear you can buy.

Long the configuration of choice for the technical diver, the backplate and wing is seeing more acceptance in recreational diving, and rightfully so.  New divers are faced with a decision to purchase a back-inflate or jacket BCD.  Rarely are they offered the third, and superior option.  The benefits of a backplate and wing over these traditional recreational BCD's are numerous.  A BP/W is infinitely adjustable to fit any size diver, is incredibly durable, easily repaired, can be modified as necessary, and is dollar for dollar a better performing, longer lasting piece of equipment.

Recreational diver
A recreational diver in a horizontal position
The recreational BCD is built to keep a scuba diver vertical, which is comfortable for new divers since this is how our bodies are oriented on land, but counter-intuitive to effective diving.

When diving, the ideal position is a horizontal one, making you streamlined in the water, much like a fish.  This is known as trim.  Proper positioning reduces the effort necessary to propel yourself in the water.

If your BCD is pushing you into a vertical position, you will be expending extra effort to remain in trim, and thus using more gas and expending excess energy, leading to a shorter, less comfortable dive.

The reason this happens is simple physics, think of a see-saw on the playground.
Recreational diver in jacket BCD
The upward force will make a diver off balance by design

Your body will pivot on it's center of gravity.  When scuba diving, this will be the extra weight you are wearing.  In a jacket BCD, your center of gravity is near your hips, and your means of buoyancy is near your chest and shoulders.

A back inflate BCD, while a better option, ultimately finds similar pitfalls.

Enter the backplate and wing.  This configuration sandwiches your center of gravity between you and your BCD, and distributes it evenly, solving this problem.
Recreational diver in backplate and wing
The BP/W balances the diver naturally
 The backplate itself serves as your weight, eliminating the need to shuffle bricks in and out of  BCD pockets.

Also, placing your center of gravity directly above your lungs, the body's internal source of buoyancy, has the same effect, keeping downward force parallel with upward force.

I'll touch more on the benefits of a BP/W in another post, but if you are looking to purchase a backplate and wing setup, but don't know where to begin or your dive shop does not carry them, I recommend Deep Sea Supply.  Owner, operators, and manufacturers are a small, knowledgeable crew who will take the time to talk you through your purchase and ensure you get exactly what you need.

Saturday, August 10, 2013

Boltsnap selection

Bolt snap Selection - what to look for

Whether you are a technical scuba diver or fresh out of your open water class, odds are you will need to purchase some boltsnaps over the course your diving career, as items will always need to be secured (for example, your GoPro).  
Gopro Hero3 Black
Not all snaps are created equal, though.  A cheap bolt snap will usually have sharp edges, not a serious issue topside, but these become tiny razors at depth ready to flay your fingers.  

The area you want to examine is around the gate, since your thumb will be moving along these edges, you want to ensure they are  smoothed.  
bolt snap gate edge
This is a shot of a bolt snap I had to grind down myself after slicing my thumb open.  Later I'll  post on the process of fixing these, but today lets focus on doing it right the first time.

Once you have determined you have a safe piece of hardware, next you''ll want to examine the closed gate.  What you are looking for is an un-exposed spring.  

The reason being, while diving, especially when in a cave or wreck, there is a real chance of debris entering the exposed spring and jamming the gate closed.  In an emergency, this could prevent you from deploying your backup light, or regulator.
bolt snap gate opening

Bolt snap size largely comes down to personal preference.  I like a roomy 3/4" to 1".  These are easy to grasp while wearing gloves, and seem to find D-rings with ease.

When it comes to material, the debate is stainless steel vs brass.  While both metals are excellent for marine applications, brass is very soft, and can wear easily with repeated use.  This causes gates to slide erratically and can potentially cause a failure.  Steel is the stronger of the two and hence does not present such problems.

A good steel snap can be purchased at most dive shops (online or otherwise), although some only carry brass, in which case I would look elsewhere.  Your local hardware store can be a valuable resource for stainless steel bolt snaps as well, just be sure and check for the features outlined here.

Once you have purchase your snaps, you'll need to attach them, here's a post to show you how.

Friday, August 9, 2013

The convenience of scuba diving tables

Diving tables. Maybe not the ones you think.

When diving freshwater, often we are not using a boat, but instead diving off a lake shore, river bank, or inland cave.  Over time I've developed a "base camp" setup that I use for these situations.  Depending on the duration of my stay and the nature of a given site the gear I bring along may vary, but there is one piece I do not leave home without.

diving tables

A folding worktable.  The same thing you might use as a sawhorse.  In particular, I like husky x-workhorse tables (they are cheap, fold flat, and are rated to 750 lbs), but anything with the right surface area and load capacity would suffice.

The benefits are numerous, but first and foremost this serves as a stand to hold your cylinders.  When gearing up, you can rest the base of your cylinder on the table for support.  After a long dive, you can rest your tank on the table while doffing, where it will stay, at waist height, ready for your next dive.

Also, your expensive life support equipment is high and dry, not rolling in the dirt.  A table also provides points to hang masks or other gear during surface intervals to drip-dry and easily keep track of.

diving table in use

This is especially important if you are diving doubles, as squatting them to and from the ground in-between dives can be difficult.  Here's a shot of mine in action.

This is the type of thing that, when you see someone else at it, you wonder why the hell you never had the idea in the first place.  Swing by your local hardware store, an pick up one for you and your buddy.

Basic wetsuit repair

Basic wetsuit repair - mending tears

is not the daunting task you may think it is, and can be easily done onsite or in your home.  This is a valuable skill to increase the lifespan of a suit, and to deal with the damages incurred by the rigors of frequent diving.

Your primary tool for this process will be Aquaseal.   This urethane adhesive is waterproof, creates and incredibly strong bond, durable, and bonds to nearly anything.  This includes your fingers, so lets learn how to properly utilize it.


Most tubes of Aquaseal will come with a small brush, which will be your means of application.  The mistake I see most divers make is to apply a metric ton of this goop.  Admittedly, this method will seal the tear, but Aquaseal dries semi-hard, and thus can affect a wetsuit's ability to stretch, not to mention looks terribly sloppy.  The trick here is to apply a minute amount to your brush, and smooth it onto either side of the tear, then press them gently together.  After hold for a moment to allow a bond to form, you can apply a small amount to the interior and exterior of your tear to further cement it in place.

Allow the seal to dry overnight (or at minimum 4 hours) and test the bond.  Pull slowly from either side of the seam and look for splits or poor adherence. 

The key is to not over do it initially.  Much like cooking, you can always add more seal, but once it is in place, there's no going back.

Wetsuits for tall skinny men


Finding wetsuits for tall skinny men

This can be surprisingly difficult. I am 6', 140 lbs and reasonably fit. Shopping for clothes is always a nightmare, but buying a wetsuit is its own specific hell. After trying on literally 10 different brands ideas of what "small" or "small tall" was I managed to find not only an wetsuit that fit, but a brand that fit me consistently. O'neill wetsuits, and the medium O'Neill Sector specifically, fit me nearly as well as a custom made suit, at 1/2 the price if you shop around. 

    An important thing to note is that O'neill makes 2 tiers of wetsuit, one is made for surfers, and as such is not as durable, nor does it handle compression at depth well.
O'neill Sector wetsuit

 The Sector line are their premium scuba suits. High quality neoprene, welded seams so you can't pull a stitch, kevlar-like kneepads, and o-ring seals for a semi-dry effect.

The seam treatment is, after the fit, my favorite aspect of this suit.  Most wetsuits, even high end ones, glue and stitch their seams.  O'neill layers a "weld" on top of this.  Basically a thick layer of Aquaseal type polymer to permanently seal them, preventing snags or abrasion.

O'neill Sector wetsuit stitching
Left: Normal seam, Right: O'neill seam

Here you can see the difference.  The O'neill suit's seams have been sealed shut, preventing them form fraying.

These retail for $300.00+, but often Amazon has them at a substantial discount.  It's hard to put a price on comfort while diving, but at this rate you won't need to.