Nanaimo Wrecks, and a PADI course

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bradells

Contributor
Messages
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Location
Calgary, AB
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200 - 499
This is my take on my PADI Wreck course over the last weekend in Nanaimo, Vancouver Island, BC.

I’m intrigued by wrecks, and having dove a few off the coast on Vancouver Island, I wouldn’t mind poking my head into them as well before they disintegrate into a bigger pile of rust. I also want to know if I can (mentally) eventually follow that rabbit down the hole that is a cave (way down the road),

On the last wreck charter I did (just before new years), I stayed outside shooting video, but quite a few of our boat teams entered the wrecks. It got me thinking, maybe I want to do that? I should get some knowledge in how, what and why to do it.

Enter Liz, who is moments away from becoming a GUE Instructor, let alone being a long time PADI Instructor, and a host of other 3 letter organizations. I’ve had the pleasure of doing my drysuit course in the past with her, and always learn a lot about diving and my abilities (or lack of) while diving with her.

I scheduled some dives over christmas with some GUE team members who I/we thought might be on the course, but it ended up being someone else altogether.

Enter, Francois, who just recently completed Fundies a few weeks prior (who is also a full Trimix diver with another organization, and already has taken a PADI Wreck course, years ago, but wanted an updated fresh take).

The approach to the course was more of a continuation of the Fundies course, with emphasis on protocols, teamwork, and incorporating the new skills from this course to add onto our basic foundation skills in the continuation our diving careers.

We did have some appointed homework before the course, which was to read and complete the PADI reviews from the course book, as well as a few other homework questions based on the material. The course was 2-1/2 days long (2 days and an evening of instruction)

The first evening was spent going over the course material, handling/tying/line work, and more assigning of homework (roughly 2-3 hrs total)

The first full day of diving, we had the charter all to our selfs (All 4 of us, Instructor, 2 students, and a video diver). There are 3 artificial reef wrecks to choose from right by Departure Bay in Nanaimo, the RivTow Lion, HMCS Cape Breton and HMCS Saskatchewan.

Since we had the boat all to ourselves, we spent the day on the RivTow Lion. A surprisingly large Tug Boat in fairly shallow, sheltered water (it’s just inside the marina entrance). This made for a great platform for the first few dives to get acquainted with wreck diving by having long bottom times and little current to complete our dive tasks.

Our homework for the first night was mainly gas planning for our dives the next day. The first two dives, were more orientation dives, with no real penetration. So gas planning required us to figure out our Depths, MDL, and gas strategy.

With us using double 12L and double 16L (HP100/HP130) tanks, we had lots of gas available for 18-24m dives.

Our Dive 1 Goals were to identify some hazards of the dive site, some areas of interest, possible penetration points, and navigational features. Also, we were required to collect some data for calculating our personal SCR.

We spent 26 minutes swimming along the wreck, and being led through some swim throughs to get used to the propulsion, and positioning methods required to navigate inside wrecks, as well as collected our required data.

For the dive being planned for 24m, we turned based on calculated pressure, not MDL.

During the SI, we had a few debriefs about the dive, our team work, and what we need to work on, mainly in our Positioning, Buoyancy, Trim, Propulsion and communication.

We calculated our new MDL, gas requirements, Min Deco for our second dive.

Dive 2 Goals were to practice tying off, and running line on the outside of the wreck.

On the stern of the tugboat, there is a giant box that has a big cut out on both the Starboard and Port sides, as well has no ceiling. This was our place to run some line. After a go with running the line, there was quite a bit of disturbed silt, so we moved to another section of the ship for more line running.

We laid quite a number of lines, got entangled, and attempted (felt like) to fit through some cutouts.

This time we hit our MDL opposed to our Min Gas, and head back onto the boat.

Again, some more debriefs on the dive from Liz, and between us in our team. Load all the gear back into our vehicles, and onto some more shocking debriefs with the magical device from the video diver. You can’t hide from the video.

Some more homework for the next day (more gas planning and working of some skills), and off we went to get our fills.

The second day of diving, the boat was full with 10 divers, and we were headed out to the bigger, and deeper wrecks.

We arrived a bit before the charter to go over the little bit of homework. A few questions about the gas planning, as the first day, we planned on using (total) 1/2 of our Usable Gas per dive, but ended with both of us having more than 100bar in our tanks at the end of the day (and we didn’t hit MDL on the first dive).

Some more theory and knowledge and we calculated a new gas strategy to maximize bottom time and headed out to the Cape Breton.

The main goal for Dive 3 is to follow laid line through the wreck itself. There is a section of the wreck behind the wheelhouse called the ‘skylights’ which goes into the engine room that is fairly popular with this wreck, as well as a helicopter platform on the stern.

Unfortunately, the midship line wasn’t available, so we were left tied into the bow line. Meaning, we might not make it to the midship (and definitely not the stern) before we hit one of our turns (either gas or MDL), as we planned on a 30M dive of 30 Minutes.

We changed our plan, and found a small room that we followed a line through, and kept heading towards the skylights, and ended up with enough time and gas to head down inside. On the way back to the upline, we did a few more tie offs and hit our MDL and headed back for the boat.

I won’t say our ascent on that dive was pretty, not even decent, but definitely not my worst …

Again, more debriefing, more planning and the usual and we moved over to the Saskatchewan for the last dive of the course.

Dive 4 Goal: Plan and execute the dive by ourselves, and run some line!

We planned a 21m dive for our second dive, to run some line through the wheel house. Tied up to Mid Ship, we were right above it.

Francois ran the line through the wheel house, and we successfully completed our goal. Run line by our selves in a wreck.

Since we were midship with 2/3 of our gas supply remaining, we spent the rest of the dive working on some communication skills, propulsion and a bit of trim (well, personally learning how to slightly successfully not cartwheel when going through a hole head first in a heavy set of steel doubles).

We hit our MDL and headed up the line for the last time.

With our newly added knowledge with gas planning, we had 2 long dives, with lots of gas still in the tanks. If we did what we were planning on doing (the same strategy as the first day), we definitely wouldn’t have gotten our two full dives.

One last quick debrief, and some celebratory beverages, we passed our course with some more skills to add to our arsenal (and to practice!)

With the 2 1/2hrs of dive time over 4 dives, I feel very confident in running line on wrecks that I have visited before, and more comfortable in our knowledge of gas planning and dive planning in general to accomplish such goals.

There are lots of places to expand a course with PADI, and with usual conditions where many wrecks can be found (cold, deep, dark water), the way our course was presented, and handled was about the best you could do for our local wrecks given the constraints of a few dives over a weekend. Emphasis on teamwork, basic dive skills with the newly added skills and preparations of penetrative wreck diving.


BRad

 
This was fun to read, as I had heard a little bit about the class from Liz. You were lucky in your instructor; she's intense and focused and very knowledgeable.

Ten years ago, I took my first steps toward cave with a wreck workshop taught by two GUE T2 divers in Seattle. It's a fabulous start.
 
The big wrecks in Nanaimo are lots of fun to dive. The Saskatchewan and Cape Breton were cleaned very carefully before they were sunk. They are also a good reason to have some decompression training. Being able to accelerate deco with EAN50 allows for time to explore the interiors.


Sent from my iPad using Tapatalk
 
Post not accessible for me. Too unqualified, I guess :),:),:),:)
Me neither...must be in the Top Secret folder which I do know the secret hand shake for or have a decoder ring that unlucky it for me. :(
 
This was fun to read, as I had heard a little bit about the class from Liz. You were lucky in your instructor; she's intense and focused and very knowledgeable.

Ten years ago, I took my first steps toward cave with a wreck workshop taught by two GUE T2 divers in Seattle. It's a fabulous start.


My first course with Liz was my drysuit just over a year ago. I had 50 dives in the caribbean (all with rental gear), and no cold water experience (cold water, drysuit, BPW, in my own gear).

Intense is one word for liz, not in the 'Intense 'Roid Rage Uber Gym Personal Trainer' way, but she sets the goals high from the start, and also gets results. I was silly enough to say, in addition to the drysuit, I think I like this GUE thing, could you do a bit of a intro/primer for me?

I only truly enjoyed 1 dive out of my 4 (and hated 1 ... well the end portion of my 3rd dive) .... The first day was ascents/descents and the table in 25ft of frigid cold water, with Liz waiting patiently at each stop and skill, watching me yoyo up and down, missing every single one.

I've come along way in the past year, with these skills transferring very well across to warm water, but sadly, coming back to cold water, I feel and look like day 1 all over again (for brief moments).

Glad you guys got the great weather for your Star Studded Fundies course, I just left when it turned sunny and warm (Calgary has been decent this week at least, no frozen beards so far....)


BRad

---------- Post added February 25th, 2015 at 10:17 AM ----------

The big wrecks in Nanaimo are lots of fun to dive. The Saskatchewan and Cape Breton were cleaned very carefully before they were sunk. They are also a good reason to have some decompression training. Being able to accelerate deco with EAN50 allows for time to explore the interiors.


Sent from my iPad using Tapatalk


My big goal this year, is to be able to enrol or even attempt T1 (my work schedule sucks for diving ... let alone being in Alberta), those wrecks are just about out of reach under the deck for 32%, and with short recreational bottom times.

I don't necessarily want to go deeper at most sites (except for the wrecks), but stay longer in the 100ft/30m range.


BRad
 
The post is in a closed forum for technical divers. It is a pretty simple post, though, going through gas planning for using thirds on wrecks with a rock bottom reserve, and how to calculate available gas for a lost buddy search. Anybody who's taken a cave class has done these calculations, and I suspect, since I know bradells' instructor, that they did quite a few of them, too.
 
Modified Thirds Planning and Calculating On-the-Fly Gas Needed to Do a Lost Buddy Search in a Wreck Penetration:

Using difficult & cumbersome US Imperial Units in PSI (the easier Metric calculation in comparison follows in a later section down below in bold):

Suppose you originally planned a wreck penetration starting with 3000 psi [double AL80’s] at the entrance, with an openwater Rock Bottom of 750psi; So 3000 minus 750 equals 2250psi usable for the penetration --Modified Thirds of this value is 750 psi (one-third of 2250 equals 750), so you would turn-around for egress when you consume 750 psi of gas with an actual SPG reading of 2250 psi. If you needed to do a gas-sharing emergency egress with your buddy at this point, you would both need 1500psi to get out of the wreck, with 750psi Rock Bottom remaining to get both of you to the surface (or your Oxygen deco bottle stop of 21&#8217:wink:.

Let’s say you used up 450psi already getting to the entrance of the wreck for a total of 2550 pressure available --can you quickly recalculate Modified-Thirds?

Well . . . 2550psi minus 750psi Rock Bottom yields 1800psi usable for the penentration; One-Third of 1800psi is 600psi which is your new Modified Thirds turn pressure value. Therefore you would turn the dive when you consume 600psi for an actual turn pressure SPG reading of 1950psi (2550 minus 600 equals the actual turn pressure SPG reading of 1950psi).

What if you lose your buddy at this instance, at the farthest distance inside the overhead your Modified Thirds value allows? How do you calculate the amount of gas to do a Lost Buddy Search?

[NOT] easy! At your turn around pressure reading of 1950psi on the SPG, simply add your Rock Bottom value to your Modified Thirds value (750psi Rock Bottom plus 600psi Modified Thirds equals 1350psi); Put a line-arrow pointing the way out on your mainline that you've laid, and take reference note of where you are inside the overhead at that exact point as well. Now go and search for your buddy with the understanding that you must be back at this line-arrow marker by the time your SPG reads this actual value (1350psi). So you would have from 1950psi down to 1350psi reading on your SPG, or 600psi delta of gas to search for your buddy --if you were to do a straight line search down a long corridor inside the wreck for example, tactically you should use 300psi out and 300psi back to your line-arrow marker for a delta of 600psi, and an actual end of search SPG reading of 1350psi-- you must start your egress whether you found your buddy or not when you use up this 600psi delta of gas, at the line arrow marker, with the actual 1350psi final reading on your SPG.

At any point before your Modified Thirds turn pressure, for a lost buddy search, the final egress pressure is figured just by adding your Rock Bottom value to the amount of gas you've consumed on the penetration up to that point --for example you start with 2550psi on your SPG and you lose your buddy with 2100psi SPG reading for a delta consumption of 450psi. 750psi Rock Bottom plus delta consumption of 450psi equals 1200psi. Drop a line arrow, and now you've got from 2100psi down to 1200psi (a tactical delta search pressure of 900psi) to look for your buddy, and be back to your line arrow to egress smartly when your SPG reads 1200psi.

At any point after your Modified Thirds turn pressure, all you need to do to figure out a final egress pressure for a lost buddy search is to subtract your Modified Thirds value from your actual pressure reading, and place a line-arrow pointing out at this point on your mainline. For example, if you're egressing and you lose your buddy with 1800psi actual reading on your SPG: Subtract the Modified Thirds value of 600psi from 1800psi -which equals 1200psi - and it is this actual reading that you must have on your SPG when you get back to your line arrow to successfully exit the wreck with all your Rock Bottom still available to reach the surface. Another way of looking at this, at your nominal turn-around point & afterward on egress, the amount of gas tactically available for a lost buddy search is always just your Modified Thirds value --in this case 600psi.

Remember that on a lost buddy search, you will deliberately encroach and use up the Modified Thirds Reserve Value needed for an emergency gas-sharing egress contingency (and possibly use up Rock Bottom as well) --in other words, if you do find your lost buddy and worst of all worst scenarios he happens to be out-of-gas in a silt-out . . .well dea ex machina. I hope you're in a 3-person Team, somehow make it out and run into other divers on the outside who can donate gas & assist. . .
_______________
Same thing as above but now using Metric Units:

Modified Thirds,Turn-Around Pressure and Lost Buddy Search Gas Availability Calculations are easier & more intuitive with a bar SPG too. . .

Suppose you originally planned a wreck penetration starting with 200 bar at the entrance, with an openwater Rock Bottom of 50 bar. 200 minus 50 bar equals 150 bar usable for the penetration --Modified Thirds of this value is 50 bar (one-third of 150 equals 50), so you would turn-around for egress when you consume 50 bar of gas with an actual SPG reading of 150 bar. If you needed to do a gas-sharing emergency egress with your buddy at this point, you would both need 100 bar to get out of the wreck, with 50 bar Rock Bottom remaining to get both of you to the surface (or your Oxygen deco bottle stop of 6m).

Lets say you used up 30 bar already getting to the entrance of the wreck for a total of 170 bar pressure available --can you quickly recalculate Modified-Thirds?

No problem with bar pressure metrics: 170 bar minus 50 bar Rock Bottom yields 120 bar usable for the penentration; One-Third of 120 bar is 40 bar which is your new Modified Thirds turn pressure value. Therefore you would turn the dive when you consume 40 bar for an actual turn pressure SPG reading of 130 bar (170 bar minus 40 bar equals the actual turn pressure SPG reading of 130 bar).

What if you lose your buddy at this instance, at the farthest distance inside the overhead your Modified Thirds value allows? How do you calculate the amount of gas to do a Lost Buddy Search?

Easy! At your turn around pressure reading of 130 bar on the SPG, simply add your Rock Bottom value to your Modified Thirds value (50 bar Rock Bottom plus 40 bar Modified Thirds equals 90 bar); Put a line-arrow pointing the way out on your mainline that you've laid, and take reference note of where you are inside the overhead at that exact point as well. Now go and search for your buddy with the understanding that you must be back at this line-arrow marker by the time your SPG reads this actual value (90 bar). So you would have from 130 bar down to 90 bar reading on your SPG, or 40 bar delta of gas to search for your buddy --if you were to do a straight line search down a long corridor inside the wreck for example, tactically you should use 20 bar out and 20 bar back to your line-arrow marker for a delta of 40 bar, and an actual end of search SPG reading of 90 bar-- you must start your egress whether you found your buddy or not when you use up this 40 bar delta of gas, at the line arrow marker, with the actual 90 bar final reading on your SPG.

At any point before your Modified Thirds turn pressure, for a lost buddy search, the final egress pressure is figured just by adding your Rock Bottom value to the amount of gas you've consumed on the penetration up to that point --for example you start with 170 bar on your SPG and you lose your buddy with 140 bar SPG reading for a delta consumption of 30 bar. 50 bar Rock Bottom plus delta consumption of 30 bar equals 80 bar. Drop a line arrow, and now you've got from 140 bar down to 80 bar (a tactical delta search pressure of 60 bar) to look for your buddy, and be back to your line arrow to egress smartly when your SPG reads 80 bar.

At any point after your Modified Thirds turn pressure, all you need to do to figure out a final egress pressure for a lost buddy search is to subtract your Modified Thirds value from your actual pressure reading, and place a line-arrow pointing out at this point on your mainline. For example, if you're egressing and you lose your buddy with 120 bar actual reading on your SPG: Subtract the Modified Thirds value of 40 bar from 120 bar -which equals 80 bar- and it is this actual reading that you must have on your SPG when you get back to your line arrow to successfully exit the wreck with all your Rock Bottom still available to reach the surface. Another way of looking at this, at your nominal turn-around point & afterward on egress, the amount of gas tactically available for a lost buddy search is always just your Modified Thirds value --in this case 40 bar.

Remember that on a lost buddy search, you will deliberately encroach and use up the Modified Thirds Reserve Value needed for an emergency gas-sharing egress contingency (and possibly use up Rock Bottom as well) --in other words, if you do find your lost buddy and worst of all worst scenarios he happens to be out-of-gas in a silt-out . . .well dea ex machina. I hope you're in a 3-person Team, somehow make it out and run into other divers on the outside who can donate gas & assist. .

[Note: the above gas plan is taken from wreck penetration dives on the HMCS Yukon (San Diego); USS New York (Subic Bay Philippines); HMAS Perth/USS Houston (Sunda Strait Indonesia); and various wrecks in Truk Lagoon. Depth 30m using twin 11L/bar tanks (double AL80's) and Oxygen deco.
 
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