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Tom, I agree, if one is not mentally prepared for a silt out, they should not be cave diving. I suppose some people who were not totally prepared to negotiate passage in 0 vis might gain a since of comfort from the warm glow and primary would offer. But one also needs to understand that, all caves are not created equal. Some caves are in a near constant state of silt out or low vis and do not warrant the use of a 50 watt or even a 35 watt primary. My choice of a 12-20 watt lamp is not advocating that it is right for caves with 20-50-100' of vis. But for low to no vis systems it is the right light for my purpose. I need the burn time over brightness, in low vis sumps a 50 watt bulb and huge cannister are not needed and in fact are usless,(can't see in 0 to 10' of water any better with 50 watts than with 12 watts) so I don't bring them. Referencing the cave in low vis means doing so with all the available means under these conditions. This can mean see what can be seen (pretty cave and all) as well as be felt (negotiate by feel). Obviously in clear water a high wattage lamp will give more available visual input, so as not to miss jumps, landmarks, and features in general. Not so obvious leads (going passage) often can not been seen ( 50 watts or not) unless you crawl right up to them and check them. I'm sure no one would recommend the use of a 50 watt light with a cannister for low vis conditions (I might be wrong). That would be bringing something for the sake of bringing it. Groping the way forward is the most effective way to explore many caves (I've tried to think it through) because more often than not, Silt Happens Regards JD At 06:27 AM 05/08/2000 -0400, Tomsits wrote: >Jeff, > >First off, if anyone is not mentally prepared for a silt out then they >should not be cave diving. > >Second... Why advocate using improper gear. A 12 Watt primary light is >useless. You loose visual definition and clarity (The cave don't look so >pretty and you can get lost:)). The ability to distinguish features may be >the difference between proper referencing and missing a jump. You would be >amazed at what you missed by using a 12W light. Use a 50W BRL bulb and see >the difference. > >Third... (Assuming your diving with proper gear) You are right. Never >turn off your primary during a dive. The chances of the bulb filament >breaking during cool down or start up is very high leaving you with the >need to exit the cave with no primary. This would turn a minor >inconvenience into a more stressful situation. > >Be cave divers and think these things through. That's the difference >between DIR and personal preference. - JT > > >At 12:52 AM 5/9/2000 -0500, Jeff Disler wrote: >>At 06:47 PM 05/07/2000 -0400, Mark Hanes wrote: >>>OK here goes.... >>> >>>If you are poking around in small silty restrictions and find yourself >>>in a white out situation...would it be better to keep your eyes open or >>>closed from a psycological standpoint?? >>> >>>I always close my eyes as this doesnt let me know I cant see..and I >>>think helps me to concentrate on the line without the mental turmoil... >>> what do you think?? >> >>When I'm diving under these type conditions, I will usually just shut off >>my light and leave my eyes open. This assuming that one already knows the >>direction of travel and are on the line heading in their desired direction. >> >>Of course if the vis is not truely zereoed, then some navigational >>information could be missed by either closing your eyes or shutting down >>the primary. >> >>Why have my light on when it not usable, I'd just might as well save the >>battery power for when and if the conditions clear (I'll check from time to >>time) or beyond the sumps. >>I have heard many suggest that shutting down a primary light during a cave >>dive is not a wise thing to do. It is true that powering up a bulb is >>probably the most likely time to have a bulb failure. Perhaps the higher >>wattage bulbs used by some have a greater chance of bulb failure during >>start up. I however usually only dive with a 12 or 20 watt bulb and have >>never had one blow during switching on. >> >>Regards JD >> >> >> >> >> >>"SILT HAPPENS"JD JEFF DISLER >> SAFE CAVING NSS 26000 >> > > "SILT HAPPENS"JD JEFF DISLER SAFE CAVING NSS 26000
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