How Much Reliance on Dive Shop Planning?

[stephen1254]

I appreciate all the responses and I will purchase a computer. This is a whole new world for us and we are still feeling our way!

 

[Lorenzoid]

. . .You need to measure time and depth somehow, and it's fine to use the eRDP or printed tables to calculate your allowable time at depth. You still need to rent or buy some sort of timing device and depth gauge. You could use a waterproof watch if the regulator that you rent comes with a depth gague in the console.
. . .

I once showed up for a dive, and the divemaster asked, "Uh, can I borrow your watch?" I handed him my Timex Ironman, and away we went. Those days before I bought my first computer are long behind me, and I shudder to think of it now.

 

[doctormike]

I once showed up for a dive, and the divemaster asked, "Uh, can I borrow your watch?" I handed him my Timex Ironman, and away we went. Those days before I bought my first computer are long behind me, and I shudder to think of it now.

Well, let's see... the sun was over that big palm tree when we splashed, and the red ribbon tied to my mask looks blue, so that means... wait, hold it, carry the two... uh...

 

[dmaziuk]

What I have now is a PADI eRDP. When I plug in the planned dive times, depths, and surface intervals, I come perilously close to the limits of a no decompression dive.

OK, so you buy a computer, it tracks your actual depths and times as opposed to eRDP's conservative guesstimate, and now the exact same dive is safely close to the NDLs as opposed to being perilously close? Of course buy a computer, but, like, really? Is that how they explained "no stop" and deco in your course?

 

[RandomGuy1]

No one else mentioned it yet, but you really need two computers. One for each of you. That way if you become separated, you will both know your time / depth / tissue loading status, or more simply if one of you decides to do an extra dive or sit out a dive.

 

[doctormike]

No one else mentioned it yet, but you really need two computers. One for each of you. That way if you become separated, you will both know your time / depth / tissue loading status, or more simply if one of you decides to do an extra dive or sit out a dive.

Excellent point!

 

[stephen1254]

OK, so you buy a computer, it tracks your actual depths and times as opposed to eRDP's conservative guesstimate, and now the exact same dive is safely close to the NDLs as opposed to being perilously close? Of course buy a computer, but, like, really? Is that how they explained "no stop" and deco in your course?

That is exactly why I made the original post. The first dive is 75' for 30 min. The eRDP shows the max no decompression time at 75' is 35 min. IF the dive goes a little deeper, say 80', and IF it goes for 31 or 32 min, that puts it over the no decompression time according to the eRDP.

Now I know the entire dive won't be at 75', or 80', but I don't know what the max no decompression time is for the particular dive profile the operation uses. My question was whether to trust the people that have been doing it several times weekly for decades, or to carry my own dive computer. I've been convinced, and will carry my own computer.

The use of the term "perilously" is because of my own self imposed conservatism here, particularly because we are really just starting out, with only 8 dives so far. It's really the wrong word to use here. My understanding is that the time the eRDP is giving me is conservative, meaning going to 75' at 35 min is a safe dive. My concern is that the dive may go a few feet deeper, and may go for a few minutes more - I don't know that, but I want to prepare for that. It is clear to me now that the only way that I will be comfortable if that happens is with my own computer.

 

[ronscuba]

In addition to a dive computer, I recommend buying your own regulators.

I've seen all ranges of quality and maintenance in dive shop rental equipment. A well maintained good quality regulator is not a given. They are almost always the given manufacturers lowest performing regulators and who knows how often the are cleaned and serviced. Plus, the mouthpiece. Think about it. Mouthpiece on a rental regulator. Who used this last ?

 

[Doby45]

Just get ya two Zoops and be done with it. Hell you can buy two regular ole Zoops and use those the rest of your recreational dive career. They are on eBay for $150 or less and you both get one and you are under $300 for a good recreational set of computers that will do Nitrox. On down the road, IF YOU WANT you can get the data cable (approx $100) and it will work on both. PS none of the listings are mine.

SUUNTO ZOOP BLACK DIVING WATCH | eBay

SUUNTO ZOOP BLACK DIVING COMPUTER BUNGEE MOUNT | eBay

 

[Kharon]

If you don't want to buy a computer just yet, you can always just rent one from the dive shop. Contact them and reserve one when you book your dive. By renting a computer first you can determine what you like, what you don't, and what features you might want.

Personally I was taught to plan multiple serial dives using tables but have always used a computer. I would describe my diving style as browsing while wandering so a strict plan doesn't work for me.