Sailing retro low tech - legal risk?

[lustyd]

but always carry 88 Tables in my bag

Do you take a copy down with you, or consult them before each dive? There're no good in your bag once you're on the bottom!

 

[Skylark]

Do you take a copy down with you, or consult them before each dive? There're no good in your bag once you're on the bottom!

You wouldn’t have asked that question if you understood my post.

 

[lustyd]

You wouldn’t have asked that question if you understood my post.

You seemed to imply you don't trust the information on the computer, if that's the case why wear it? If you do use the computer but want a backup in case it fails, then the tables should be in your BCD pocket

 

[Skylark]

You seemed to imply you don't trust the information on the computer, if that's the case why wear it? If you do use the computer but want a backup in case it fails, then the tables should be in your BCD pocket

Nothing that I’ve written implies that I don’t trust the information on the computer. You don’t seem to understand the subject that you introduced. It’s about interpreting the information presented.

 

[lustyd]

Nothing that I’ve written implies that I don’t trust the information on the computer. You don’t seem to understand the subject that you introduced. It’s about interpreting the information presented.

One of us has missed something, but I'm sure it's not me. I understand the subject very well indeed, thanks.

 

[Buck Turgidson]

a) pretty sure he wasn't
b) what model of phone do you have as I tried to figure out what system my iphone uses and couldn't come up with an answer. I doubt its as accurate a system as the flux gate ones in a tiller pilot for example.

But still regardless of phones do plotters ever have a flux gate compass internally or rely on calculations based on movement

Iphone. Currently 11 but previous 8 also had a compass function both magnetic, both accurate. My Garmin forerunner watch also has an accurate compass built in too. They are very common on chip sensors.

Plotters generally don't hence to many heading sensors available. I have 2 on my boat one Navico and one Garmin even though I don't have a plotter. I use my iPad. The heading sensors feed my Triton 2 .

 

[lustyd]

My Garmin forerunner watch also has an accurate compass built in too

I wrote a ConnectIQ app for Garmin watches which can send out the various bits of data in real time. The compass works in all three dimensions accurately, as do the accelerometers, so it's not important which way up the watch is. We even managed to get it to recognise trips and falls for use with vulnerable folk to call automatically for help.

It's the accelerometer data, not the compass data, that improves autopilot function. Predicting wave movement allows predictive steering. It ideally needs to be mounted centrally to achieve this as the forces differ throughout the boat.

 

[DownWest]

A (small scale) builder friend of mine refuses to buy a laser level as he always charges by day rate and sees efficiency as a way to make less money. I'd rather get the job done in half the time, charge the same, in fact a bit more to cover the expensive tools that the client can see me using, and do a second job on the other day or take the day off..

A late friend ran one of the top NYC studios for decorating. When paint rollers first appeared, the Unions effectively banned them for their members as, too easy and too quick. Saw them as a threat .

 

[WannabePirate]

I'm curious, are there any SCUBA divers on the thread who still use tables and a watch as their primary tools? It's been a long time since I saw anyone dive without a computer, but arguably these add very little to the experience.

I wouldn't say that I use tables and a watch as my primary tool....but after about 20 years and 10,000+ dives I have a fair idea of my decompression obligations without the need for tables or a computer. I typically (not always) will dive with 1-3 computers and use my knowledge of decompression theory to double check the computers both against each other (they're set for different gradient factors anyway) and against what I would expect. It's nice to stack the odds in your favour in exploratory cave diving...

Basic rule for air diving - 20 mins at 30m NDL (min deco technically). Add 10min for every 5m shallower and remove for 5m deeper. Past the NDL its about 1:1 air deco ratio up to an hour. How you shape this will be up to you.

I can do this for a wide variety of depth and gas mixtures. It's an idea known as "ratio deco" and is heavily advocated by an agency known as "GUE". They also advocate diving without computer. The name is a bit of a misnomer because it actually isn't just based on a ratio. It's based off noticing patterns in your common dive plans using your preferred tables and gases.

Same as when sailing, I use a variety of tools at my disposal. I dive with a computer but always carry 88 Tables in my bag. My computer uses a similar Haldane model algorithm to the Table so simply eats-up any safety margin compared to the conservatism of assuming square profile.

Pushing the envelop to believe that I am that average person with which the model was developed doesn’t seem that wise to me. With more than a thousand dives under my weight belt, I’ll continue with this approach and not have blind-faith in the information shown on a computer screen. DCI is not something to gamble with.

You've clearly read a bit more on the topic than the average diver. I'm gonna guess your haldane based computer is running some sort of Buhlmann ZHL-A/B/C algorithm? It's worth noting the Haldane model and 88 tables are widely discredited. Much of it is speculated to come from the use of Navy divers for the baseline, but another major speculation is that it pushes too much decompression, especially in the wrong place. This was the same issue with VPMB or bubble models. Unfortunately VPMB and bubble models heavily influenced decompression theory in diving and widely introduced deeper stops across the sport. Even changing the recommended Buhlmann gradient factors. Most computers come preplanned with a GF of 35/85 or because this ends up with a similar profile across common dives to VPMB models...but 50/70GF seems to be the modern safest way for go. I personally typically dive with 1 computer at 50/90, a second a 100/100, and a third (rarely) at whatever I feel like on the day. I add my own safety factor. My needs are different to most.

Another thought on the navy divers: you know for up to 40 minutes they have a max recommended ppO2 of 2.5bar? I believe BSAC currently recommend 1.3bar. We are talking different levels of risk acceptability.

Some food for thought/research for a clearly prudent diver

 

[srm]

Surely there is a middle way?

I have the electronic toys, but not the latest incarnations, and turn them on or off as appropriate to the situation. I also have a magnetic compass in the binnacle, another for reference at the forward end of the deck house where I spend a lot of my time offshore, and the relevant paper chart on the chart table below the screens. Steering is by windvane, as it has no power drain, unless motoring.

Sailing in Norway, inside the islands, I used a small scale paper chart for planning and to avoid heading down dead ends with the plotter and 1:50,000 paper charts giving the larger scale details. The paper charts gave a better rendering of the land forms than the electronic ones.

I simply use whichever aids are appropriate at the time, without worrying if its Mk I eyeball and transits or extended ground track vectors on the plotter.

 

[WannabePirate]

A not-even-new-yet sailor question: is there a cost difference in the two options besides the initial outlay on equipment? Specifically in the charts.

Seems paper charts are quite expensive, seems you need a lot to cruise an area, and seems they'll wear out/need replacing to be most useful. This seems like quite the annual bill. A chartplotter subscription getting you access to a very wide area at lots of different scales seems less? I've noticed some people saying you can just get apps on your phone.

 

[lustyd]

Specifically in the charts.

Yes, and the more you look at the pricing the more you realise there's no rhyme or reason to it.
Paper charts are what they are, and you have to buy a bunch of them even for a single location because they only support a single level of "zoom" expect to pay 20 bucks per sheet. A friend sailed around Britain and spent about £2k on leisure folios. Then you have to manually update them which is time consuming and tedious, but is usually free unless they decide to stop supplying updates (as in the leisure folios when changing edition). This also assumes you have space on board to store enough for wherever you go. They do have the distinct advantage of being able to be drawn on directly with a pencil, and despite the name, are generally waterproof or at least very water resistant.
Electronic charts for plotters get cheaper the more you buy. Generally a couple of hundred bucks for large area versions which cover half a continent or so, and less for a single area. For the UK and Ireland it's £150, so cheaper than the £2k above which did not include all of Ireland. These include all zoom levels so just need to buy the one thing. An annual subscription is half that cost and updates the charts through magic so you have more time for gin.
Then you have Navionics and the like on phones and tablets. Inexplicably this is a fraction of the cost of the same chart for a plotter but has all the advantages of electronic. UK and Ireland about £40
And finally, Navionics web app which only works when you have an Internet connection, but is completely free.

 

[srm]

A not-even-new-yet sailor question: is there a cost difference in the two options besides the initial outlay on equipment? Specifically in the charts.

Seems paper charts are quite expensive, seems you need a lot to cruise an area, and seems they'll wear out/need replacing to be most useful. This seems like quite the annual bill. A chartplotter subscription getting you access to a very wide area at lots of different scales seems less? I've noticed some people saying you can just get apps on your phone.

Yes, paper charts have always been expensive. Having had access (many years ago) to UKHO offices in Taunton for work I fully understand why. I have been told that, for some reason, UKHO sold off their databases to electronic charting companies at a knock down price quite some time ago giving electronic charts a commercial advantage.

Now UKHO is phasing out paper charts so detailed large scale cartography on paper will soon be a thing of the past. However, small scale wide area charts such as produced by Imray provide a useful planning and passage making overview, and when combined with pilot books that give detailed harbour/anchorage plans are more than adequate in many areas for the leisure sailor.

If your sailing area is relatively small and budget tight then the paper route could be sensible, especially if the sea bed does not change from year to year so the only updating will be shore lights etc. For bigger cruising areas going electronic with small scale paper charts for an overview and planning will be most economical.

 

[WannabePirate]

From

...For the UK and Ireland it's £150, so cheaper than the £2k above which did not include all of Ireland...

Thanks! From a human factors approach thats a really interesting thing for me to learn. That kind of price difference is a substantial influence in most skippers decision making process I imagine.

I'm a keen land navigator. I'll get a very accurate fix most places on earth without a compass, dead reckon (on land and underwater) and enjoy proving I can do it. Done various surveying too. I've been reading this thread (and some navigation handbooks) imagining I'd like to paper base my nav on board, and use electronics for convenience/accessory.

That kind of price difference though? Well that changes my idea from my idea of perfect; to a few large scale charts of difficult areas, small scale charts of cruising areas, and relying on electronic charts a lot more.

Yes, paper charts have always been expensive. Having had access (many years ago) to UKHO offices in Taunton for work I fully understand why. I have been told that, for some reason, UKHO sold off their databases to electronic charting companies at a knock down price quite some time ago giving electronic charts a commercial advantage.

Now UKHO is phasing out paper charts so detailed large scale cartography on paper will soon be a thing of the past. However, small scale wide area charts such as produced by Imray provide a useful planning and passage making overview, and when combined with pilot books that give detailed harbour/anchorage plans are more than adequate in many areas for the leisure sailor.

If your sailing area is relatively small and budget tight then the paper route could be sensible, especially if the sea bed does not change from year to year so the only updating will be shore lights etc. For bigger cruising areas going electronic with small scale paper charts for an overview and planning will be most economical.

Seems you informed whilst I was writing this that the UKHO have also (been forced by commercial factors as opposed to human) to make this decision.

 

[Buck Turgidson]

From


Thanks! From a human factors approach thats a really interesting thing for me to learn. That kind of price difference is a substantial influence in most skippers decision making process I imagine.

I'm a keen land navigator. I'll get a very accurate fix most places on earth without a compass, dead reckon (on land and underwater) and enjoy proving I can do it. Done various surveying too. I've been reading this thread (and some navigation handbooks) imagining I'd like to paper base my nav on board, and use electronics for convenience/accessory.

That kind of price difference though? Well that changes my idea from my idea of perfect; to a few large scale charts of difficult areas, small scale charts of cruising areas, and relying on electronic charts a lot more.




Seems you informed whilst I was writing this that the UKHO have also (been forced by commercial factors as opposed to human) to make this decision.

I use both. From the same supplier. Imray Paper charts and Imray Navigator app on my iPad.

 

[Skylark]

I wouldn't say that I use tables and a watch as my primary tool....but after about 20 years and 10,000+ dives I have a fair idea of my decompression obligations without the need for tables or a computer. I typically (not always) will dive with 1-3 computers and use my knowledge of decompression theory to double check the computers both against each other (they're set for different gradient factors anyway) and against what I would expect. It's nice to stack the odds in your favour in exploratory cave diving...

Basic rule for air diving - 20 mins at 30m NDL (min deco technically). Add 10min for every 5m shallower and remove for 5m deeper. Past the NDL its about 1:1 air deco ratio up to an hour. How you shape this will be up to you.

I can do this for a wide variety of depth and gas mixtures. It's an idea known as "ratio deco" and is heavily advocated by an agency known as "GUE". They also advocate diving without computer. The name is a bit of a misnomer because it actually isn't just based on a ratio. It's based off noticing patterns in your common dive plans using your preferred tables and gases.




You've clearly read a bit more on the topic than the average diver. I'm gonna guess your haldane based computer is running some sort of Buhlmann ZHL-A/B/C algorithm? It's worth noting the Haldane model and 88 tables are widely discredited. Much of it is speculated to come from the use of Navy divers for the baseline, but another major speculation is that it pushes too much decompression, especially in the wrong place. This was the same issue with VPMB or bubble models. Unfortunately VPMB and bubble models heavily influenced decompression theory in diving and widely introduced deeper stops across the sport. Even changing the recommended Buhlmann gradient factors. Most computers come preplanned with a GF of 35/85 or because this ends up with a similar profile across common dives to VPMB models...but 50/70GF seems to be the modern safest way for go. I personally typically dive with 1 computer at 50/90, a second a 100/100, and a third (rarely) at whatever I feel like on the day. I add my own safety factor. My needs are different to most.

Another thought on the navy divers: you know for up to 40 minutes they have a max recommended ppO2 of 2.5bar? I believe BSAC currently recommend 1.3bar. We are talking different levels of risk acceptability.

Some food for thought/research for a clearly prudent diver

A very interesting post, thanks for taking the time to comment.

I’m no longer as up to date as I once was (evidently ?). My bedtime reading in the early 90s was mostly either Lippman or Cole. Mid to late 90s was a time of rapid development in mixed gas recreational diving, linked to better understanding of decompression theory.

Once upon a time I was very engaged with BSAC diving, training and development.

I’ve always preferred to take a conservative approach to avoiding DCI. Long gone are my days of deep and repetitive dives leading to mandatory stops. That’s why I always check square profile, no-stop by Tables, but dive using the computer.

BSAC has a very low ppO2 threshold. I first did a nitrox course with IANTD, a good few years before it was approved by BSAC. At that time, 1.8 bar was considered max, with due consideration to both acute and chronic toxicity.

Getting hooked on sailing put paid to my active recreational diving career.

 

[WannabePirate]

...I’m no longer as up to date as I once was (evidently ?)...

I hold the advantage of regularly being invited to conferences where leading experts give very well prepared and researched talks on these subjects.

I exploit this by not attending the talks; and hounding them with questions in the bar all night.

 

[Stemar]

A chartplotter just tells you where you are (hopefully with a good degree of accuracy)
It has very little idea which way the wind or tide is taking you.

Your CoG compared with your heading will tell you that. I would suggest that anyone who's out in any but the most benign conditions in safe water and doesn't have a feel for that is already at risk of having to answer some difficult questions if a Coroner gets involved. If you're the skipper, you are expected to have a reasonable level of skill.

 

[Skylark]

It's worth noting the Haldane model and 88 tables are widely discredited.

Risk of thread drift, sorry ?

I have some free time so I’ve googled “BSAC 88 Tables widely discredited” but didn’t see anything of note, can you point me in the right direction, please?

I should probably first ask “what sort of diving do you do”?

 

[WannabePirate]

Risk of thread drift, sorry ?

I have some free time so I’ve googled “BSAC 88 Tables widely discredited” but didn’t see anything of note, can you point me in the right direction, please?

I should probably first ask “what sort of diving do you do”?

I've about 10,000 dives. Last 10 years mostly cave dives. Experienced with all kinds of gases, CCRs, gear configurations. Multiple 100m+ BT60min+ dives. Worked with various agencies in various ways. Have basically no qualifications. (Very common in sailing, not a lot of us in diving). My advice and recommendations come with many caveats based around this. To be 100% clear I am also in no way a scientist/expert in anything.

Mindful of thread drift, but also public transparancy: "Widely discredited" may have been a bit of hyperboly, especially in respect to the 88 tables. My apologies.

My comment was more aimed towards the Haldane model. I used it as specific issues have been identified with it and it is a scientific model. Buhlmann models were developed from it. The modern scientific consensus seems to prefer Buhlmann as the development of the old model with issues. BSAC 88 tables are tangentially (but basically) based on Haldane models. None of this was meant to imply the 88 tables were unsafe to follow though. (please don't go trying to follow Haldane models straight though)

PMs are open.