May 2015 - DSAT Courses and Trips!

May is normally the last month of peak season here in the Philippines and we thought we'd make the most of this with trips to both Coron Bay and Verde Island.

Our Coron trip was our first trip back to the Coron Wrecks for almost a year so it was great to get back, catch-up with people and dive again in the best wreck diving location in the Philippines.  We even had time to pull together a few video clips from this trip; the YouTube links below should give you an idea of what to expect - we'll be planning regular trips there every 3-4 months.

Coron, Irako Maru Wreck - https://www.youtube.com/watch?v=9dREXbn6E4U
Coron, Kyokuzan Maru Wreck - https://www.youtube.com/watch?v=WGQVO23rl9o

Making the most of the near perfect weather we also arranged a trip over to Verde Island from Anilao.  This trip went really well and is something we'll be doing a lot more of in the near future.  The boat ride from Anilao is around 90 minutes, so is longer than the PG trip but the large (PG ferry) sized boat we used made it a really comfortable trip.  The trip was done over a full moon weekend so some crazy currents were around, especially at the Washing Machine site when the tide was on a strong ebb.

We'd also like to pass on our congratulations to Cesar who this month completed his Tec45 course after a few weeks of diving with us.

The weather here is holding up well with conditions still hot and sunny and no rain it sight (yet!) so we're looking forward to more great dives in June with CCR, Technical and Instructor courses lined up here in the Philippines.

Colour Coding of Standard Gases

We've decided to start using a colour coding system for all of our decompression and bail-out tanks as part of our annual stage tank overhaul.

The intention of this isn't to use the colour coding underwater, but to make visual recognition of tanks much easier on the surface, especially then having tanks passed town from boats on while donning tanks at the shoreline.

The colour coding also provides a quick visual reference underwater (we only used colours at the end of the visual spectrum - i.e. black, white, greens and blues).

We normally use standard gases for all our courses;

Black on White - Oxygen for Decompression from 6m upward
White on Black - 50% Nitrox for Decompression from 21m upward
White on Blue - Trimix 18/45 from 67m upward
White on Green - Trimix 10/70 from 130m upward.

The only other standard gas we use tend to use for decompression is Trimix 35/25 which we tend to make specifically for dives rather than have as a pre-filled standard gas.

Modifying my BMCLs for the Hammerhead Extreme CCR

I've started to make a few adjustments to my new Hammerhead CCR this week, in general the unit works a dream; but one minor concern I had is that the unit doesn't breath well as you move to a head down position due to air becoming trapped in the bottom of the lungs and not being able to reach the shoulder mounted T-pieces.

I don't really plan on being in a head down position too often, however wreck or cave diving can often require this and I didn't like the idea of restricted or unbreathable operation when more than likely being in a restriction.

Hose wraps on BMCL T-pieces

The modification suggested by Randy from SubGravity was the addition of the standard scuba hose wraps into the the lungs.  I actually didn't dive the unit without the wraps inside the lungs so can't comment on any improvement but I felt the sharp edges of the wraps could increase the risk of puncturing the lungs, while the performance with the wraps still made breathing slightly more difficult when horizontal and noticeably difficult when orientated head down.

I wanted something softer inside the lungs that gave a greater opening area to keep an airway between the t-pieces and the bottom of the lungs, initially I was thinking of a 1 inch diameter chemical braided hose (like a large diameter hose pipe) but was a little worried about the effect on minimum loop volume - a long length of large diameter hose would create quite a bit of dead space which I didn't want to carry in the lungs.  The hose also needed to be soft enough to not interfere with the lungs or risk damage, but firm enough to avoid collapse when under a negative pressure in the lung.

Standard firm garden hose with holes

I weighed up a few different options and had intended to try two or three different options, namely a standard garden hose, a slightly larger hose and the larger 3/4 inch hose.  My final choice was just to go with the garden hose as the hardware store nearby only had that in stock unless I bought the full 20m hose!  I had two choices, soft or firmer and went for the firmer hose type.

I cut the hoses to reach from the t-piece to around 10cm/4" from the bottom of the lungs - this could mean I couldn't quite work them at absolute minimum loop volume but was willing to sacrificial that to avoid the end been sealed or increased risk of water in the hoses.

To stop water entailment from the bottom of the lungs into the breathing loop, and to allow gas movement from anywhere in the counter lung, I drilled several large holes in the hoses.  I had originally intended to drill more larger holes but found they made the hose shape more flexible and was concerned the hoses could close up and reduce the breathing area when under a negative pressure in the lung.

Hose connection on BMCL T-piece

The hose was then tied using a cave line with two half hitches to the counter lung t-pieces, keeping the hose and as close as possible to the t-piece connection.

Performance wise I definitely noticed a significant improvement in the work of breathing when fully horizontal, head down was still noticeable harder to breath but it did prevent the complete close-up of the lungs - although the breathing resistance was still very high.

I've since added a second hose to each counter lung to double the hose opening are, the second hose was added in the same way as the firs.  Adding the second hose seems to line up well with the t-piece water trap openings.

I've not yet had a chance to dive the unit with the second hose so can't compare performance, however I'm hoping there's a further improvement - logic would suggest breathing should be easier again given the increased hose sectional area in each lung.  Sadly I don't think I'll get a chace to dive the unit again for almost 2 weeks due to other commitments but as soon as I do I'll give an update on how it works!