Volcano National Park
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I'm looking at this and kinda scratching my head. Are you grounded or something and looking for a get around?
And when you're going through the lava fields and maybe you start twitching pretty good, everyone else there will get some really memorable vacation shots. It's pretty cool walking where Mark Twain observed a lake of liquid fire.
And when you're going through the lava fields and maybe you start twitching pretty good, everyone else there will get some really memorable vacation shots. It's pretty cool walking where Mark Twain observed a lake of liquid fire.
Dr. Lecter
Contributor
Figure out the elevation to which you'll have to ascend in the park, the length of your SI, and answer your own question. My thought is that it's a very shallow dive, and only one tank, you should be fine. Use nitrox if you can. But since I couldn't care less if you get bent, I wouldn't rely on my gut feeling if I were you.
LeadTurn_SD
Contributor
This is a late response, but we get asked this several times a year, so here goes:
I'm with the good doctor on this one. Sounds like "tough love", but his point is important, and we do get asked this type of question (and I often answer it) fairly frequently.
Here is the information you need in order to answer the question for yourself, which is the only prudent thing to do.... NEVER trust anyone else do decompression calculations FOR you:
1. What altitude do you plan to ascend to?
2. What will your dive profile be (number of dives, depth and time of each dive).
3. What will your surface interval be prior to ascending to altitude?
I use the tables in the U.S. Navy Diving Manual, specifically Table 9-7 "No-Decompression Limits and Repetitive Groups"; Table 9-8 "Residual Nitrogen Time for Repetitive Air Dives"; and finally Table 9-6 "Required Surface Interval Before Ascent To Altitude After Diving".
You do need to know how to use these tables, and you can't mix the Group Designator from the PADI RDP for example with the Navy Ascent to Altitude tables. You need to use the Navy tables.
You can ascend to the altitudes in Volcano after a "typical" shallow single tank dive, but the longer surface interval you can take the better. After multiple dives on the same day, you definitely want to consult the dive tables to determine an adequate surface interval.
Remember, multiple shallow dives, due to their longer bottom times, can still leave you with a high nitrogen load, even though you did not exceed no-decompression limits. You do need to consider this. Shallow and long can result in higher loading than deep and short.
Finally, Dr. Lecter answered the OP's question in his 2nd sentence. After a surface interval of many hours following a shallow single dive it should be "fine" to ascend to the altitude of Volcanoes National Park (around 4,000 feet).
Best wishes.
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I wouldn't go to the top of Mauna Loa though..
The Saddle Road over to Hilo also reaches 6636' along the way.
The Saddle Road over to Hilo also reaches 6636' along the way.
Token
Contributor
What is the _lowest_ elevation/route between Kona and Kapoho [on the coast S of Hilo]? I'd love to do a few dives either at Kona or even Kohala, but having to overnight away from our rental digs at Kapoho isn't too appealing cost-wise...
If you go to (for example): MapQuest Maps - Driving Directions - Map and access driving directions from Kapoho Point Beach to Kailua Kona, you’ll see there are three options.
The shortest in miles (but not necessarily time), depending on where you are going is about 110 miles via highway HI-200 (Saddle Road). But it is also the highest elevation, and as mentioned by diversteve exceeds 6500 feet, so that one’s out.
The next shortest, about 10 miles longer is via HI 19, and more northern. Playing around with the topo maps at Hiking Trails, Mountain Bike Trails & Trail Maps | Trails.com you can see that you’ll only reach about 2900 feet (if I read the maps right). That would be your best bet. Kohala would be somewhat closer than Kona. Figure two-and-a-half to three hours driving time
For completeness, the third option via HI-11, adds another 15 miles, passes though Hawaii Volcanoes national Park, is the southernmost, and approaches 4000 feet.
This might be a bit off topic and I have not had to research it myself for any occasion yet, but I will ask/comment anyhow.
I thought I read some of the threads a while back that the "no fly" rule had to do with the rate of ascent as opposed to the actual elevation. Just like you would not go from 130' to the surface as fast as you can it makes sense that flying or rapid ascents up hills would not make sense.
I will do some more looking around online but thought someone might have links off hand. On quick search all I can find is stuff that has to do with flying or diving at altitude.
I thought I read some of the threads a while back that the "no fly" rule had to do with the rate of ascent as opposed to the actual elevation. Just like you would not go from 130' to the surface as fast as you can it makes sense that flying or rapid ascents up hills would not make sense.
I will do some more looking around online but thought someone might have links off hand. On quick search all I can find is stuff that has to do with flying or diving at altitude.
LeadTurn_SD
Contributor
As knotical mentioned, Highway 19 through Waimea is the lowest route. I use 3,000 feet as the rounded elevation.
I can't emphasize strongly enough how important it is to do your own calculations if you are planning to do this. I will routinely dive in Puako (single dive) in the morning, then drive back to Hilo via Highway 19; but I know the maximum Repetitive Group on the Navy table I can attain when I dive this site to a depth of 55 feet and 55 minutes (a typical suck the tank dry dive for me at this location), I come out of the water with Group I; with Group I my required SI before I can ascend to 3,000 feet is 0:56 minutes. It takes me that long to swim to shore, take off my gear, put on dry clothes, load the truck.... you get the picture.
But if I do a 2nd dive, that entire picture changes. If I wait 2 hours then do a 2nd dive, even though it is shallower, I could easily reach a Group Designator that calls for a 5 Hour wait before driving back to Hilo.
I don't "push" any of these limits.
If you are planning to dive 2 or 3 tanks on the same day, you really should consider waiting until the next morning to drive, unless you've carefully done the calculations for yourself.
I personally will stay overnight if I do multiple dives in a day.
Best wishes.
---------- Post added December 16th, 2013 at 01:40 PM ----------
I don't have a good answer, so I'd search this forum, or maybe ask Dr. Deco directly:
Ask Dr. Decompression
Best wishes.
Im pretty certain the overriding factor is elevation. Rate of ascent would be a very minor factor, more theoretical than realistic.
Consider a slow rate of ascent in water of 10 fpm - quite conservative. The greatest pressure ratio gradient is in the shallowest water, say from one foot of depth to the surface. At 10 fpm, the pressure would decrease by about 3% in 6 seconds in that last foot of ascent.
To realize a similar rate of pressure change after surfacing, one would have to ascend over 900 feet in 6 seconds or about about 100 mph vertically! I am unaware of any land vehicle or commercial aircraft approaching that kind of performance.
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