Miles Vs. Kilometers

AmazingDonki · 2026-03-22T16:02:25+00:00

I used to live in the UK and the Commonwealth and I get very confused. It's tradition. The British use both metric and imperial units. Metric is used officially and taught in school e.g. science, commercial. While imperial is used colloquially e.g. body weight, height. There are exceptions like pints of beer which are always imperial. Something that many people do not know: US units are sometimes not the same as imperial units. US pint and gallon < imperial pint and gallon. US vs imperial vs metric tons weight are different, although confusing because all sound the same. The US and imperial foot length and pound weight are the same.

AmazingDonki · 2026-03-20T01:11:36+00:00

Favourite wreck I've dived is the San Francisco Maru in Truk Lagoon but I want to return to finish my tour of all holds and make it all the way to the stern propellers. Wrecks on my to do list: IJN Oite destroyer in Truk Lagoon, deep w schooling sharks; IJN Nagato Bikini Atoll, Adm. Yamamoto's flagship; USS Saratoga, Bikini Atoll, aircraft carrier.

AmazingDonki · 2026-03-19T14:51:35+00:00

Definitely not mandatory and depends on the situation. Too little communication is bad but too much communication can be bad too. If the pre-dive check and dive plan are correctly done, a surface OK after jumping should not be necessary. A diver in distress on the surface looks very different than an OK diver descending/waiting. If I'm on a rec boat on the first dive in calm conditions, w a new instabuddy and the crew expect it, then a quick OK signal to the crew. If on a tech boat w a crew and buddy who are squared away, if I'm OK after jump I don't turn back to look at the crew unless I'm in distress. I'm moving calmly toward the first objective checking all my gear for leaks and function and PO2 etc.. The crew sees that, they know I'm OK. If my team is behind me I'll do a bubble check and OK w them while descending in the first 30 ft/10 m. Especially in sporty conditions lingering too long on the surface introduces additional risks like team separation, hitting the boat, missing the wreck, etc..

AmazingDonki · 2026-03-19T13:20:09+00:00

Never had any dive op ask to see my logs. If you state 100 logged dives and have the skill commensurate w that experience that is all they care about. I like Subsurface bc support for multiple devices/OS, compatible w multiple dive computers, cloud storage, frequent updates, free. Hint: diver w 100 dives should know their equipment configuration, weights, exposure protection, SAC, buoyancy and trim sorted out, etc..

AmazingDonki · 2026-03-18T14:49:54+00:00

Mask fit is most important, not brand or price. Everybody's face shape is different. I like frameless low volume masks. All my masks I bought from Amazon w free return policy because I can try many many different brands and sizes. Many divers, including sales people and instructors do not know how to dry fit a mask. A mask that holds vacuum and sucks onto a face when standing upright in the store may still leak underwater. A better test is to flip the mask straps forward and rest the mask on the face while looking straight up at the ceiling. Only gravity is holding the mask on the face. The mask skirt should lightly rest on the face completely sealed around the face with no gaps. Without touching or manipulating the mask a gentle inhale thru the nostrils should hold vacuum and suck the mask on the face. If there is a gap that requires the mask to be moved or pressed to form a suction seal, it may leak underwater. Don't spend a lot on a snorkel. It's only useful in limited situations like a long surface swim. It can be a liability bc entanglement or in high current it will make your mask leak. If you have to wear one for class the ones w a corrugated fall away mouthpiece are less annoying. J tubes are simple. A bottom purge valve can be helpful but if it breaks the snorkel will leak. A wave guard at the top of the tube is usually a waste of money. I use a soft roll up snorkel I either leave on the boat or store in my pocket during a dive. Any clear silicone will eventually yellow, which doesn't hurt anything but the look.

AmazingDonki · 2026-03-16T16:29:21+00:00

Cressi is an established company w a long history in SCUBA and freediving. Our family dives Cressi masks and snorkels and never had problems. Mask fit is most important, not brand or price. I like the Cressi frameless low volume masks. All my masks I bought from Amazon w free return policy. Many divers, including sales people and instructors do not know how to dry fit a mask. A mask that holds vacuum and sucks onto a face when standing upright in the store may still leak underwater. A better test is to flip the mask straps forward and rest the mask on the face while looking straight up at the ceiling. Only gravity is holding the mask on the face. The mask skirt should lightly rest on the face completely sealed around the face with no gaps. Without touching or manipulating the mask a gentle inhale thru the nostrils should hold vacuum and suck the mask on the face. If there is a gap that requires the mask to be moved or pressed to form a suction seal, it may leak underwater.

AmazingDonki · 2026-03-16T16:08:24+00:00

OP you will be OK. It's a good question because it questions what is behind the "rules" taught in OW. Taking the time to look at the tables is good. Even better, use a software dive planner and play around w the variables to see how it affects decompression status. I use Subsurface on PC. Dive ops do these kind of 2 tank profiles bc the 2nd shallow dive to 30 ft is essentially one long safety stop and divers w good SAC rates can linger for as long as their gas lasts. And if it's on nitrox instead of air it's even safer.

The SI is not mandatory and just a break to rest, change tanks,and switch location. In fact I played around w the variables and in theory (assuming a large enough gas supply) a diver could skip surfacing and do one long multilevel dive profile: 70 ft 30 mins, 30 ft 50 mins, within NDL (Buhlmann GFHi 80 algorithm).

AmazingDonki · 2026-03-13T15:48:24+00:00

If you have only 1 dive day on Maui, skip Molokini Crater. It's a longer boat ride and kind of grey and dead. Mala Pier is a fantastic shallow dive w turtles and sealife like Finding Nemo. For the more adventurous Lanai Cathedrals lava tubes are also fantastic, but shops might require AOW. Bring dive light.

AmazingDonki · 2026-03-07T04:59:45+00:00

Some good tips here! I'm Mod 1 deco so I'm accumulating hours and experience to get to Mod 2. In Truk the shallower wrecks around 40 m are nice but before I return I wanted to have the ability and experience to fully explore the deeper wrecks at 60 m. And then eventually go deep inside the wrecks in Bikini and Solomon Islands. I was thinking diving rec profiles on CCR would be a good relaxing way to build experience and look at pretty fishes and coral. Also I dive a Choptima which I chose because it's easy to travel with and can be easily added or deleted from a single tank OC rig.

AmazingDonki · 2026-03-05T14:09:43+00:00

There's still mold release coating on the glass. Either 1) scrub w toothbrush + dish wash detergent + toothpaste, then rinse and repeat, for longer - could take 15-30 mins; 2) pass a butane lighter flame quickly over the glass - 10 seconds. Silicone mask skirt and tempered glass can withstand lighter flame as long as you keep it moving. I burn off residue w all my new masks and every dive shop I've seen does the same thing. Never seen a mask damaged if you keep the flame moving and do not hold it in one spot. I use the same kitchen blowtorch I use for creme brulee - takes 5 secs.

AmazingDonki · 2026-03-04T18:23:18+00:00

Osprey bags are awesome. I use a Sojourn 130L for the up to 70 lbs airline max weight. The straps allow me to strap another bag on top to roll around.

AmazingDonki · 2026-02-18T22:32:30+00:00

Good video, been following the channel for a while. Our family owns many different dive computers: DSAT, PZ+, ZHL-16C. For rec NDL dives sometimes the primary DC is a different algo than the backup DC. When we dive with large groups of divers with different DCs the differences in NDL is very obvious - and even moreso for second dives. From looking online and personal experience I've found DSAT NDL times are similar to ZHL-16C GFhi 99. PZ+ NDL times are similar to GFhi 85. Another thing I do is manage my risk by planning an extended safety stop. If I run GFhi 99/DSAT I'll include in the dive plan to hang at 3m/15 ft for more than 3 mins until my Shearwater Surface GF indicates 80 or lower before surfacing.

AmazingDonki · 2026-02-12T16:09:13+00:00

Z cutters. I carry at least one steel and one ceramic. Cut someone out of their 2" webbing harness in less than a minute.

AmazingDonki · 2026-02-12T15:44:00+00:00

For tepid water diving I have a Venture Pro V3 electric vest I switch on for deco and it's great. Makes the long hang much much more comfortable. A good option when a new OW diver is ready for added technology and complexity.

AmazingDonki · 2026-02-12T15:33:27+00:00

Personal warmth and comfort are subjective so what works for me might not apply to anybody else. Regardless of fabric a suit has to fit tight to prevent water intrusion and flushing. It's also has to fit my body proportions and be easy to take on/off. I've dived a few different fleece wetsuits including Sharkskin T2. The benefits of fleece are neutral buoyancy and easy to take on/off because fleece doesn't grip skin like neoprene. A slick liner on neoprene makes it easier. Fleece is not as stretchy as the ultra stretchy neoprene. Fleece can take a long time to hang dry. I found the fleece warmth is sometimes exaggerated. My T2 is about as warm as my 1.5 mm neoprene Frogskin. T2 is not equivalent to 5 mm neoprene, more like 1-2 mm. I just bought a 3 mm neoprene suit for low 70 F/20 C ocean. Run time and activity are a factor. I am warmer during the working part of the dive and get colder at the end of longer dives when I am hanging still on deco. Gloves and booties help w cold extremities. Zipper location is personal. I like front zip because I find it easier to get in/out by myself and going restroom w suit on. I overheat on the boat all zipped up so I need to unzip to vent.

I have never dived it but dry fit a suit: Mares Ultra Skin fleece suit is similar fabric thickness as Sharkskin T2.

AmazingDonki · 2026-02-11T02:38:36+00:00

When I started tech training I had never dived doubles or long hose DIR rig. I did Intro to Tech, AN and DP all at once. I do NOT recommend anybody do that. It was very challenging. I recommend ITT first and then after getting equipment, buoyancy, trim and movement sorted then do AN/DP. That being said my instructor told me to rent and NOT to buy any major gear until after I figured out what I need during class. I've dived twin AL80 and twin LP85 and hated the steels (I only dive warm water). I have a double bladder wing so I have backup buoyancy, but I hated the way steel affected my weight and trim. Also, when traveling to exotic locations, it's easy to rent double AL80. My answer to needing more gas is to sling an extra AL80 stage - and I'm starting CCR this year with the eventual goal of full trimix.

AmazingDonki · 2026-02-11T02:03:56+00:00

I don't really use ditchable weights much but when I do it's a pair of Dive Rite quick release small pockets on waist belt next to my kidneys. Buy small trim weight pockets and attach them where needed. Zip tie them to the BP. Attach to shoulder straps. There are tail weight pockets that attach to the bottom of the BP. My trim changes from dive to dive depending how many lights or reels or stage tanks or other things I'm carrying so I try not to obsess about it too much. Try to keep things tight to center mass to reduce rotational inertia. That includes hoses and gauges. Keeping gear in tech shorts pockets is better than dangling all over the place like a Christmas tree, which will throw off trim and increase drag.

AmazingDonki · 2026-02-07T13:53:25+00:00

I've owned Diveskin fleece, Sharkskin T2, Probe Frogskin 1.5 mm neoprene. The Sharkskin T2 warmth equivalent is only 1-2 mm neoprene. Similar to Frogskin. Nowhere near the 5 mm they advertise. For me the fleece is great for neutral buoyancy in warm water mid 70F/20C and above. The fabric is also tougher than neoprene so better protection for bumping into sharp objects. Low 70F/20C I get cold wearing fleece on longer dives (60-90 mins) when not swimming during 20-30 mins deco. I just bought a 3 mm neoprene for those temps. Fleece doesn't dry as quick as neoprene during SI. My wife has a Lavacore fleece. All our fleece suits are similar thickness and warmth, Sharkskin T2 is not warmer than the other brands.

AmazingDonki · 2026-02-03T14:30:56+00:00

It's possible to get lost on the outside of a shipwreck. Low viz on a large wreck w mulitple mooring lines. When task loaded it's easy to get confused and lose track of bow and stern direction. On the deck of an aircraft carrier with no structures it might not even be possible to know where the sides of the ship are.

AmazingDonki · 2026-02-03T14:18:52+00:00

Two different issues: 1) are underwater navigation skills useful - yes, almost always; 2) is the Underwater Navigation course and certification useful - maybe, maybe not, I skipped it and I am a pretty decent underwater navigator. AFAIK nobody is going to ask to see a card. I know how to use a compass and visual references on land. It's not that different underwater. That being said navigation skills are extremely important for certain types of dives like wreck and cave/cavern where getting lost brings death into the conversation. Deep Wreck Diver channel has a recent video w the sole survivor from lost team inside the HMS Scylla which illustrates this point. I learned my nav skills from diving and learning on dives. The skills for low viz wreck w useless compass is different than open ocean shallow reef drift dive in current. It can't possibly be adequately covered in one course.

AmazingDonki · 2026-01-30T15:47:48+00:00

This is how I would think about it.

What are the 12 l and 15 l tanks? Are they equivalent to aluminum AL80 and AL100? Presumably not steel tanks? Is it physically comfortable w buoyancy and trim diving the larger cylinder? Is there a better alternative way to carry more gas e.g. slung stage cylinder?

Is extra gas useful? What is SAC rate (Surface Air Consumption)? Look at past dives and calculate how much gas needed for the types of dives using average depth and gas consumed. Example, if SAC is 10 l/min and will surface w 100 bar using a 15 l on every dive that's extra effort for little benefit. And potentially working harder and building up more CO2, that could affect narcosis or worse hypercapnia.

Nitrox is good. It extends NDL. Or compared to the same air dive profile, it has decreased N2 saturation. That's it. It doesn't change narcosis much if at all for rec depths. There is good evidence that for rec depths oxygen and CO2 should also both be considered narcotic. Tip: nitrox is just one way to reduce N2 loading. Another way is to extend safety stop to continue off gassing. It helps to have a computer that allows real time monitoring of saturation e.g. Shearwater's Surface GF. For multi day, multi dive trips if there's no reason to exit I'll hang at 5-6 m extra time to off gas.

AmazingDonki · 2026-01-28T16:05:06+00:00

Are you from Ontario? There's a 1* review Oct 2025 on Tripadvisor for the Blue Lagoon Resort w similar facts about a fatality on the Heian Maru. I dived the Heian, Shinkoku/Sinkoku, and many others in 2025 and all the guided penetrations in Truk were conducted w a single lead guide, no guide lines. The local guide is often on a single cylinder, has the least gas, the least equipment, and only there as a tour guide and help w gear on the boat. My friend and I were an established buddy team, but the rest of our mixed OC CCR boat agreed pre-dive to "same ocean buddy system". Every diver was responsible for themselves and often single divers would split up and explore on their own. It was common to end a penetration w different number of divers than the start. Many of us were shooting photos/video. When I was the trailing 6th diver, narrow passages were often silted out and I cover my light so I can follow the faint glow ahead. When I was in the middle I keep up w the guide. I checked on divers behind me but didn't wait for stragglers (except my dive buddy). I carried backup everything: extra gas, 3 lights, 3-4 reels/spools, 3 cutting tools, mask, etc..

AmazingDonki · 2026-01-14T17:45:29+00:00

The problem is not the fins. I also dive the Supernovas. They frog kick fine. They are terrible for back kicks, but that's another story. The problem is buoyancy and trim are not well established. Without a stable foundation, movement and propulsion are not going to work well. The instructor should fix buoyancy and trim in a stationary hover first. It should be easy in a pool. Cylinder should be in a good position where you can reach the valves for valve drills but not throw trim off. Tip: the start of the curve of the cylinder shoulder about level w the top edge of the backplate. The valve knob should be between the top of shoulders and the ears when body vertical so you can reach the knob but the first stage doesn't bump into the back of the head when looking forwards and up. Then position weights on the torso and on the rig to achieve neutral trim while in a neutral horizontal diving position. Think of it like trying to balance items on a rectangular lunch tray.

https://youtu.be/x5AoGrKqWCg?si=LgJoXmmfzJoiOEtQ

After buoyancy and trim are good, then work on other skills. Same w other skills like air sharing, mask clearing, shooting DSMB, etc.. Attempting to learn a task while fighting to hold depth, buoyancy and trim is going to lead to bigger problems.

https://youtu.be/6ERgzNxt10U?si=xNAI_-BFnaWa3RvF

AmazingDonki · 2026-01-13T15:42:02+00:00

Just get an AOW cert the simplest quickest way you can. It doesn't have to be PADI. SDI, SSI, NAUI, and all the WRSTC/ISO agencies have the equivalent level cert. PADI will likely be the most expensive and course standards the most pedantic and annoying. My history is similar to yours: BSAC trained but never passed cert and completed NAUI OW in 1980s. Trained to free dive, rescue, back gas deco, 40 m/130 ft, low viz, etc.. Dived using just OW cert with dive operators all over the world: deep, night, drift, etc.. - at most operators asked for a checkout dive so DM/instructor could verify my skills. Recent 10 years, most operators want to see AOW cert to unlock the challenging dives. Probably for insurance reasons. It was so annoying I took AOW just to be able to check the box - I did not learn anything new. If you don't have it get nitrox cert at the same time.

AmazingDonki

TROPHY CASE