Puerto Rico

"Steve" <SPAMTRAPglawackus@hvc.rr.com> wrote in message
news:qtLQd.10458$qn2.1960790@twister.nyc.rr.com...

> I can't promise that you won't get bent if you drive to 3000' an hour
> after the dive, but I will offer an unconditional guarantee that the car
> won't suffer an explosive decompression that exposes you to less than 0.5
> ATA. If it was safe to surface it should be safe to drive as high as the
> roads around El Yunque go, about as soon as you can get there.

I'm not really worried about the 3000-4000' range, though it's notable that
most if not all of DAN's reported incidents of DCS from flying after diving
do not involve explosive decompression. I once asked Karl Huggins what he
thought about driving to altitude after diving. He used the example of a
group of firefighters from Big Bear, CA that came to Catalina for a "chamber
dive". He had advised them to spend the night at sea level before returning
home to an altitude of 7000-8000'.

This is the sort of situation where I'd shell out a few extra bucks if
nitrox is available even if we don't plan on using it for extra bottom time.

> You don't say anything about a light, but you do have one, right?

Actually, that's my next question(s). What kind, how many, etc.

I drove through the mountains last month and 2.5 hours is about right.
There are a couple of tricky turns so get good directions. I am told
that going along the coast is prettier, but the roads are not as good.
In any case, you have to get out of San Juan and the highways--even the
toll road--are two lanes at most and not quite as good as on the mainland.

If you don't believe me, look at the condition of the cars around you.

Greg Mossman wrote:

> "Dr. Yak" <DrYak@nospam.com> wrote in message
> news:TzQQd.43159$Vg3.36136@lakeread05...
>
>
>>I drove through the mountains last month and 2.5 hours is about right.
>>There are a couple of tricky turns so get good directions. I am told that
>>going along the coast is prettier, but the roads are not as good. In any
>>case, you have to get out of San Juan and the highways--even the toll
>>road--are two lanes at most and not quite as good as on the mainland.
>
>
> I live in L.A. Our highways are some of the worst-repaired in the mainland.
> Puerto Rico will be a nice change of pace.
>
>
>
Greg,

I will be in San Juan from 2pm until 10pm on a cruise - do I have dive
options, or should I just imbibe on the local beverages - be advised I
have stopped drinking for another month or so!

"Joe English" <jenglish@wisperhome.com> wrote in message
news:d5ef7$4213e232$ce504905$25673@allthenewsgroup s.com...

> Greg,
>
> I will be in San Juan from 2pm until 10pm on a cruise - do I have dive
> options, or should I just imbibe on the local beverages - be advised I
> have stopped drinking for another month or so!

If you're in San Juan from 2pm until 10pm on 3/25 then you definitely have
drinking options. Fortunately that's over a month away.

Greg Mossman wrote:


> I'm not really worried about the 3000-4000' range, though it's notable that
> most if not all of DAN's reported incidents of DCS from flying after diving
> do not involve explosive decompression.

That's only because so few of us are exposed to an explosive decompression. I'm
guesing that most people who get hits while flying are just the traveling subset of
people with undeserved hits or who pushed the limits a little too hard.


> He had advised them to spend the night at sea level before returning
> home to an altitude of 7000-8000'.

As a crude estimate off the top of my head, if an 8 hour compartment had twice the N2
it would normally have at surface pressure it would lose 8/16ths of the excess in the
first 8 hours, 4/16ths in the next 8 hours, then 2/16ths, 1/16th, 0.5/16, etc. Even
if the offgasing was linear through the first 8 hour half life you'd lose 1/16th of
the excess in the first hour. That 1/16 means you can reduce your ambient pressure by
about 2fsw, 1.15psi, or 6%. Atmospheric pressure drops at about 3 to 3.5% per 1000',
so after only an hour you should be "safe" at 2000'.

OTOH, I don't realy know that much about the intricacies of deco, so maybe I've
missed something important.

>>You don't say anything about a light, but you do have one, right?
>
>
> Actually, that's my next question(s). What kind, how many, etc.

I've got no suggestions about what kind, but unless it's really bright and you use a
filter, you won't get great results without at least one light. My first trip with a
decent UW setup (well, I borrowed a Nikonos for a trip or two in the past, but I'm
not counting that) has left me convinced that I *need* a 2nd strobe for the next
trip. FWIW IIRC, the photo pro at Sam's was only using 1 light. Maybe the harsh
shadows aren't as big a problem with video, but I expect you'd stilll get footage of
the bicolor sponges that I have stills of. You know, the ones that are pink on the
side towards the strobe and blue on the side away from the strobe. If your girlfriend
isn't up on UW photo basics, as was the case with my wife, expect questions like
"where are the pictures of the pretty blue sponges I pointed at?"


--
Steve

The above can be construed as personal opinion in the absence of a reasonable
belief that it was intended as a statement of fact.

If you want a reply to reach me, remove the SPAMTRAP from the address.

Joe English wrote:

> be advised I
> have stopped drinking for another month or so!

Have you stopped looking in the mirror, too? You've got some kind of black crap all
over your forehead.

--
Steve

The above can be construed as personal opinion in the absence of a reasonable
belief that it was intended as a statement of fact.

If you want a reply to reach me, remove the SPAMTRAP from the address.

"Steve" <SPAMTRAPglawackus@hvc.rr.com> wrote in message
news:z%RQd.10983$qn2.2001486@twister.nyc.rr.com...

> That's only because so few of us are exposed to an explosive
> decompression. I'm guesing that most people who get hits while flying are
> just the traveling subset of people with undeserved hits or who pushed the
> limits a little too hard.

Then that would push up the number of undeserved hits if they're truly not
deserved, making the ever-so-safe dive tables that much more risky. I'd
rather blame the hits on flying too soon after diving.

> I've got no suggestions about what kind, but unless it's really bright and
> you use a filter, you won't get great results without at least one light.
> My first trip with a decent UW setup (well, I borrowed a Nikonos for a
> trip or two in the past, but I'm not counting that) has left me convinced
> that I *need* a 2nd strobe for the next trip. FWIW IIRC, the photo pro at
> Sam's was only using 1 light. Maybe the harsh shadows aren't as big a
> problem with video, but I expect you'd stilll get footage of the bicolor
> sponges that I have stills of. You know, the ones that are pink on the
> side towards the strobe and blue on the side away from the strobe. If your
> girlfriend isn't up on UW photo basics, as was the case with my wife,
> expect questions like "where are the pictures of the pretty blue sponges I
> pointed at?"

With UW photography, I'm happy using one strobe in clear water. I have two
DS-125s for cold water use, but on tropical dive trips I only bring both
along so I can rotate them between dives allowing the other to charge (and
serve as a backup). The TRV-900 is a 3-chip video camera so it shouldn't
need so much light. I mainly want video to capture the big animal stuff
that doesn't let you get close enough to make the light matter. Still, I'm
looking into some sort of light source for deeper close-up work and for
night dives. Strapping on a single UK Sunlight with diffuser might serve my
purposes.

Greg Mossman wrote:

> I'm guesing that most people who get hits while flying are
>>just the traveling subset of people with undeserved hits or who pushed the
>>limits a little too hard.
>
>
> Then that would push up the number of undeserved hits if they're truly not
> deserved, making the ever-so-safe dive tables that much more risky. I'd
> rather blame the hits on flying too soon after diving.

Some of them are certainly people who didn't wait long enough. When I said "subset of
people with undeserved hits", I'm figuring that if x% of dives within the limits
result in an undeserved hit, then y% of people who dive within the limits and then
fly after waiting 24 hours should be expected to get undeserved hits, too.



> The TRV-900 is a 3-chip video camera so it shouldn't
> need so much light. I mainly want video to capture the big animal stuff
> that doesn't let you get close enough to make the light matter.

In that case losing a stop or so to a filter may not pose a big problem. I expect
Ampbibico makes a filter for your housing, but if not, perhaps an Ikelite one will
fit. Make sure there are no air bubbles trapped behind it or autofocus will result in
a lot of footage of blurry scenery beyond the nice sharp bubbles. Learning stuff like
that is a one good reason for a shakedown trip before taking it someplace exotic.


--
Steve

The above can be construed as personal opinion in the absence of a reasonable
belief that it was intended as a statement of fact.

If you want a reply to reach me, remove the SPAMTRAP from the address.

Steve wrote:

>
>
> Joe English wrote:
>
>> be advised I have stopped drinking for another month or so!
>
>
> Have you stopped looking in the mirror, too? You've got some kind of
> black crap all over your forehead.
>
oh my god, what is it?

Greg Mossman wrote:


> Right. So the x% that we've all viewed as a insignificant risk as far as
> our own risk-taking preferences is now really x+y%, a much higher figure.

Possibly significantly higher as a percentage of X, but still zero as a practical matter.


> Still, I thought we were talking about flying without waiting 24 hours.
> That's my concern. I have no problem waiting 24 hours and then driving to
> 3,000'. Problem is, I'm probably not going to wait that long.

Both my old and new computers have always shown me as being clean well before 24
hours are up. And I've usually been close to clean by the morning's first dive even
after a night dive the previous evening. If the computer says I'm clean I'd be
extremely surprised if a flight caused a problem after only 8 or 10 hours, but
waiting 24 has never been a hardship. For a drive to 3000' I'd feel completely
confident to get in the car an hour after the dive and head for 1000' and get above
that after a couple of hours. As a practical matter if you do a morning dive, rinse
your gear and change, have lunch, and then start the trip you should have a solid 2
hours of offgassing and be safe for an afternoon in El Yunque. I could be wrong, but
I'd do it if that was a conveneint schedule.



> I hate autofocus. That's one reason why my Ike housing for my Sony still
> camera is so beat up. Whenever I'm in less than perfect viz conditions, all
> I get are crisp clear photos of plankton. Unfortunately the macro isn't
> good enough to resolve the little buggers into more than just dots or I
> might have something interesting.

I'll get around to starting a thread on my camera and the results but here's the
short version. It's a Nikon Coolpix 5400, which is 5 MP (as near as I can tell the
model number of all the name brand non-slr cameras tells you roughly how many MP).
It's got full manual capability, but as a 35mm film user I find much of it
inconvenient if not downright barbaric, largely complicated by a bunch of stupid
automatic bells and whistles. I'm pretty happy with the results, though. I've put
some stuff in an Ofoto album, and I'll get around to posting a link.

I'm not fond of autofocus, but it is convenient in the housing, at least when it
works. Too many of the controls do multiple things because some MBA thinks cameras
need to keep getting smaller. Of course the screen is too small, and I now need
inserts for my mask more than ever. That said, as long as I pay attention the
autofocus does a decent job, but it's slow. I've got some shots where I think the
camera focused closer than it should have, but I have to take blame for most of the
problems. I still haven't used it in really bad viz, so maybe I'll find that to be a
problem. I've got a fondness for small stuff that doesn't run away, so quickly
changing focus isn't a problem most of the time. The problem with manual focus is
that the only way to confirm that your set distance gives a sharp image is to see it
on something a lot bigger than the camera's LCD screen. I'm quite pleased with the
closeup capabilities, though I haven't tried for something extremely tiny. I do have
some good shots of secretary blennies, and some others have some sharp coral polyps.
The 28mm (equivalent) setting focuses to about 1cm, but even without a housing you
can't really get that close and get good lighting. About the best I could do with the
housing is perhaps 3 inches. Cropping to a 1500 by 1000 pixel image results in
closeups of perhaps a 2" by 2" area that's more than good enough for the computer
monitor. As soon as you zoaom much beyond 28mm the minimum focus increases to 18",
so I have to balance short distnce against a wider field of view. My biggest
complaint is that the edges of bright areas tends to have a blue fringe from
chromatic aberration, which is most noticable in the closeup work. From what little I
know so far about digital, I gather that's a fairly common problem, and I'd guess
that the ridiculously short focal lengths make it worse than with a 35mm setup.
There's a decent version of Photoshop in my future, and that will at least help that
concern.

Okay, so that wasn't especially short.


--
Steve

The above can be construed as personal opinion in the absence of a reasonable
belief that it was intended as a statement of fact.

If you want a reply to reach me, remove the SPAMTRAP from the address.