Nav. Dive Idea in Chilly Florida

[PCBCaptChris]

OK, so I have been bating an idea around for a while and I finally have time to do it. So, I'd like to get some feedback from a few people to see any points I am missing and any ideas to make it safer/more efficient.

Here it is: I want to navigate 1200 feet from one wreck to another (better than watching TV). The bottom is sand in-between the two wrecks with a depth of 78feet. I have gone much further in caves and know this should not be a problem as far as gas consumption with a set of doubles. I haven't run the numbers, but I suspect I'll run into a fair Deco obligation and so I'll probably lug a stage along.

The navigation is the tricky part. I have never gone this far before, an even a one degree error in heading could put me in the sand/free float for my deco (not very fun for a long time....). My thought was I'd tag the down current wreck with a buoy, mark the up current wreck and get a compass heading. Enter the water, leaving the boat on the surface to live boat and mostly follow bubbles. I'd use kick cycles to measure distance. I had thought about using a reel for distance with my buddy, dono if all the trouble would return much though. I am also throwing around the idea of sending a GPS up on fishing line(I'd spool it)... However, I do not want to rely on this method as a primary...

Leme' know if you have any ideas...

Thanks!

 

[paulwall]

OK, so I have been bating an idea around for a while and I finally have time to do it. So, I'd like to get some feedback from a few people to see any points I am missing and any ideas to make it safer/more efficient.

Here it is: I want to navigate 1200 feet from one wreck to another (better than watching TV). The bottom is sand in-between the two wrecks with a depth of 78feet. I have gone much further in caves and know this should not be a problem as far as gas consumption with a set of doubles. I haven't run the numbers, but I suspect I'll run into a fair Deco obligation and so I'll probably lug a stage along.

The navigation is the tricky part. I have never gone this far before, an even a one degree error in heading could put me in the sand/free float for my deco (not very fun for a long time....). My thought was I'd tag the down current wreck with a buoy, mark the up current wreck and get a compass heading. Enter the water, leaving the boat on the surface to live boat and mostly follow bubbles. I'd use kick cycles to measure distance. I had thought about using a reel for distance with my buddy, dono if all the trouble would return much though. I am also throwing around the idea of sending a GPS up on fishing line(I'd spool it)... However, I do not want to rely on this method as a primary...

Leme' know if you have any ideas...

Thanks!

If 78 ft was to the sand, I suspect you could avoid some of your deco obligation by doing your navigation 15-20ft off the bottom, this might improve your field of vision, as well.

As long as you are sure your surface markers are properly placed, I don't see why you should have much problem using the same bearing underwater. Of course, I'm navigationally challenged, and wouldn't attempt such a feat. I'd be more inclined to drop a weighted line on the downcurrent wreck, spool off 1200 feet, drop it on the upcurrent wreck with a weighted riser/buoy on each end, then follow the line underwater.

How long do you think it would take you to swim the 1200 feet? Crap, that's nearly a quarter mile!

 

[PCBCaptChris]

At a nice lazy, wearing a bag, doubles, and a stage, pace probably an hour + deco.

I hadn't thought about running a line the entire way. I suppose I could use the line from my reel (very small, I think #18 braided...). I'd probably want to bounce down an tie it to the wreck. That way I’d be sure it wouldn’t break loose from all the tension while spooling out. The only problem would be clean up... I wouldn't want to have to spool it all back up... Of course I wouldn't want to leave it there either...

 

[PerroneFord]

What? 78ft for an hour = obligatory deco? What mix? Old Navy tables were 60ft for 60 minutes on AIR with no deco. With 36% I doubt you'd have any deco at all. Make up some 40-45% and you're golden.

 

[SuPrBuGmAn]

Depending on pace, you really shouldn't incure any deco, as PerroneFord stated, with any mix richer than air(I've nearly hit deco on Destin Jetties once - LOL). If current is light, or non-existant, it shouldn't take you very long to hit 1200'. Get off the bottom as Paulwall stated and its even less of a problem.

Spooling 1200' will require one hellova primary or the use of several standard sized primaries - LOL. I'd hate to go purchase two bigass explorers for this one dive

Since you cavedive, think of it in terms of Jackson Blue... The 2nd "T" is ~1350', the distance is easily reached in 1/3rds and you can be there in back in much much less time than an hour, and depending on pace, with little or no deco obligation. All this with depths that level off at 90-95'.

Its the actual navigation part that will be a PITA. Have a buddy follow 10-20' behind and able to use your primary line to line up with his compass? Use a strong light for signalling when you need to compensate/correct/whatever.

 

[PCBCaptChris]

I actually used JB to approximate the time... As I can remember off had where I am at what time in the dive... I won't have a hard ride in and an easy ride out to play with either. I have added time for stopping once I get there and hanging out a while... I figure I'll do 38%...(40 is 1.35...)

Yeah the nav is the thing I am debating which angle to approach. I don't think I'll use a continuous line because of the logistical concerns. I have seen the nav boards combat divers use for extended blue water, typically shallow, navigation. These guys do some extreme distances. However, I believe they stare at the board the entire time (not so fun after 20 minutes...).

 

[Zieg]

Which wrecks are you planning on using?

 

[PCBCaptChris]

I have three spots in mind with some variation in distance. What I am leaning torward now is Jeff A and 14...

Here's a picture of an LCAC... The US Navy -- Fact File

 

[paulwall]

Spooling 1200' will require one hellova primary or the use of several standard sized primaries - LOL. I'd hate to go purchase two bigass explorers for this one dive

Just mount a reel on the back of the boat. Tie a float on the end, and 100ft down, tie a 10lb weight. Toss on site one. unspool 1200ft of line while crusing over to site 2, and tie off another 10lb weight. Drop it over, and spin off another 100 ft, and a float. Voila! You've connected the wrecks!

like:Dive Rite Classic Reels

A couple of bleach bottles, and some sash weights, and you're golden!

 

[PCBCaptChris]

I think the 10 pound weight would get pulled off of the wreck as a spooled it out from the boat. I could bounce and connect it to the wreck. However, they're only 450' on the primary... So I'd need more than one... Kinda expensive. I hate to drop my reels of the side connected to the next peice of #24 not cetain I'll recover it... It may work though... I'll see if my dive buddy will let me use his reels instead

I think sound navigation would work out better. Any ideas on some distance navigation techniques?