Diving & Site-seeing .

[SouthSideScubaSteve]

I will be visiting Oahu in February with my family and plan to dive at least 2 or 3 days; we are also looking at doing some hiking, maybe Maunawili Falls or Manoa Falls, or both. I was planning on alternating days of diving with other activities with my family.

I am wondering if I need to be concerned about changes in altitude while driving around / touring the island on my days above sea level. I have searched the DAN site and find some references to questions on this topic, but all the data and recommendations seem to center around elevations (or equivalent air pressures) above 2000ft. With that, I am wondering what the local perspective / experience is …

With the elevation changes involved (I can’t find exact max elevations for either hike), do I need to abide by the DAN 18 hour rule for multiple/repetitive dives &/or wait until the “no fly” clears on my computer (Suunto Gekko) before heading off on one of these hikes? …. If not, should I keep the computer with me on my off days?

 

[Scuba_HI]

the hikes you are mentioning are not that high I would not personally worry about it but thats just me.

 

[friscuba]

This site Na Ala Hele - Hawaii Trail System: Oahu Trails has information on a lot of trails. It's got the hikes you've mentioned at 300 and 800 feet. I'm not sure if that's total elevation, or elevation change during the hike. If you can find a topographical map of the areas you're looking at you'll probably be able to find out the rough elevation within a hundred or so feet.

 

[Hinalo]

On my last dive trip to Oahu I stayed part way up Tantalus at about 1600 ft elev. I asked some local dive pros about that same issue and got a uniform response from everyone: "shouldn't be a problem." One guy said that I'd probably spend an hour or two offgassing at sea level and that would be a good thing after a couple of deep dives, but not to worry. And I thought about it last October when I was in Kona driving over the 1000' elevation from honaunau to kailua kona right after a shore dive. And, while everyone is different, none of this was a problem for me.

 

[kanonfodr]

I'm in agreement with all the above advice. I don't think either of those hikes get particularly high. Also, i live in one of the highest towns on the island (mililani) and I drive up there every day and feel no effects provided I have not blasted through any ascents. Take your time ascending and maybe practice deep stops for faster off-gassing if doing any sub 60-foot depths.

Peace,
Greg

 

[MauiScubaSteve]

Not much to add except it seems to me that the long not so deep dives that fully load the slow tissue are theoretically more of an issue with regards to elevation after diving than quick deep dives that just load the fast tissue. Fast on gassing - fast off gassing; slow on gassing - slow off gassing. Thought that's what I read anyway.

 

[SouthSideScubaSteve]

Not much to add except it seems to me that the long not so deep dives that fully load the slow tissue are theoretically more of an issue with regards to elevation after diving than quick deep dives that just load the fast tissue. Fast on gassing - fast off gassing; slow on gassing - slow off gassing. Thought that's what I read anyway.

Great point on the slow tissue loading… After reading your post, I went back and looked at the tissue saturation data from my computer on a series of dives I did last fall around Fort Lauderdale and it’s pretty interesting.

On a day where I did 4 total dives (all shallow and long) I had a SI of more than 2x my total bottom time (to that point) between the 2nd & 3rd dives (morning & afternoon charters). During that time my slow tissue saturation dropped by only 25% (from 17% to 13%); while the fast tissue saturation dropped by 100% (from 65% to 0%). Unfortunately, the dives I had scheduled for the next morning got canceled, so I don’t have any data to look at 12-15 hours after the last dive

Since my plan is to do a couple of shallow dives in the first afternoon we are there, maybe I’ll have to go for a swim the next morning and wear my computer … All it will take is to get it 3ft underwater and it will record a “Dive” that I can then download to see if it thinks I’ve completely off-gassed my slow tissue … Hmmm, I wonder if I can get DAN to underwrite my research??