Yep. Not interested in setting sled records. The function of the sled is really just to extend our training season in the lake. It'll let us do deep dives (with all the associated pressure and equalising stresses) in thicker suits when the water is cold.
-
Welcome to the DeeperBlue.com Forums, the largest online community dedicated to Freediving, Scuba Diving and Spearfishing. To gain full access to the DeeperBlue.com Forums you must register for a free account. As a registered member you will be able to:
- Join over 44,280+ fellow diving enthusiasts from around the world on this forum
- Participate in and browse from over 516,210+ posts.
- Communicate privately with other divers from around the world.
- Post your own photos or view from 7,441+ user submitted images.
- All this and much more...
You can gain access to all this absolutely free when you register for an account, so sign up today!
Variable weight dives and hydro drag
- Thread starterUnclejake
- Start date
Thread Status: Hello
, There was no answer in this thread for more than 60 days.
It can take a long time to get an up-to-date response or contact with relevant users.
It can take a long time to get an up-to-date response or contact with relevant users.
Points taken (we do the same) and agree that in that case it's better to be head down but then if this is the case, there's not that much point worrying about fairings etc unless I am missing something guys? (just asking so that I can learn, I know very little about sleds...). It might be more realistic to actually not put fairings?
Out of interest, how does the descend speed during the freefall phase of a CWT dive (say 40m+) compare with the sled descend speed of say just below 2m/s?
Out of interest, how does the descend speed during the freefall phase of a CWT dive (say 40m+) compare with the sled descend speed of say just below 2m/s?
Yes it is fun 
wish I could equalise better though, I struggle when going fast...
Another thing that's fun to do is drifting sideways on a sled - once you get down, just inflate it enough to make it neutrally boyant and then you can hold on while it's drifting (it does eventually start going up usually). Have only tried this in shallow depths a couple of times...
Posted via Mobile Device
wish I could equalise better though, I struggle when going fast...Another thing that's fun to do is drifting sideways on a sled - once you get down, just inflate it enough to make it neutrally boyant and then you can hold on while it's drifting (it does eventually start going up usually). Have only tried this in shallow depths a couple of times...
Posted via Mobile Device
There are plenty of VWT profiles in her Facebook gallery:
http://www.facebook.com/insights/#!/album.php?aid=156242&id=137800684465
.
It would be easier to eliminate the fairing, but I do want to minimise diver stress (water velocity pressure) and fairings look cool too.
I have spent days trying to make a deadman's brake that requires minimal diver input to hold it open. We may as well continue in that direction and build something awesome.
I reckon it will be the best freediving sled in New Zealand (admittedly, there are no other sleds in NZ, but that is hardly the point)
Some poor bugger will need to haul the weight up by hand Simos.
Not me I might add. I am the consultant and need to observe all the processes with due care and therefore couldn't possibly get in the way of such endeavours
30 kgs of akward drag shouldn't be that hard to pull up from -130m.... .....
Not me I might add. I am the consultant and need to observe all the processes with due care and therefore couldn't possibly get in the way of such endeavours
30 kgs of akward drag shouldn't be that hard to pull up from -130m.... .....
Last edited:
Unclejake, is your sled really 30kgs? Wearing a 6mm or 7mm suit?
I built a weight about 3 years ago that was 10kg. It was fun but slow. We used it to 100ft (had a hundred foot rope and just tied a knot it the end). I built it from a couple of extra dive weights and some other things laying around the house. haha
I'm currently building a weight thats 20kgs out of a couple Military Bombing Range practice bombs. I'll post a pic when I'm done.
Riley
I built a weight about 3 years ago that was 10kg. It was fun but slow. We used it to 100ft (had a hundred foot rope and just tied a knot it the end). I built it from a couple of extra dive weights and some other things laying around the house. haha
I'm currently building a weight thats 20kgs out of a couple Military Bombing Range practice bombs. I'll post a pic when I'm done.
Riley
Attachments
It does sound like it could be the best Freediving sled in nz - it's all about looking cool and I'm sure you can come with some scientific reason of why pulling that weight up is the best training ever - maybe put a rowing machine in a boat and tie the weight at the end of the rowing machine
In any case it should be better than jumping from the edge of a quarry while holding a heavy rock (not that I know anything about that lol)
Posted via Mobile Device
and I'm sure you can come with some scientific reason of why pulling that weight up is the best training ever - maybe put a rowing machine in a boat and tie the weight at the end of the rowing machine In any case it should be better than jumping from the edge of a quarry while holding a heavy rock (not that I know anything about that lol)
Posted via Mobile Device
It isn't finished yet Riley so I dunno, but I figure the un-ballasted sled will be around 15kgs. The lake where it will be used is around 8 degrees C diwn deep so a 7mm suit is likely.
I would love to see some photos of your contraption!
Here is the throttle on our sled. It is a plumbing ball-valve that is yet to receive a soft alloy insert (to prevent damage to the descent line).
The spine and handlebars are tack welded together in this photo, but there is heaps more to do. It is all 316 stainless steel.
We turned up some alloy solid round bar to form these hawse pipes which will guide the sled over the descent line.
The throttle you saw at the top of the page will control descent speed, but as we will be hauling the sled up by hand I was keen on a deadman's brake. This is a brake that is sprung to stop the sled unless the diver has a firm hand on the handle bar. Here is that brake assembly (unfinished).
The rough looking alloy bit you see (above) is inside the stainless sled spine (below).
So; that is two weeks of mucking around shown in photos, and I guess there is another two weeks to go before the sled is finished and ready to test. I am not an engineer (or a freediver really) so things are going slowly. It is a fun project though.
The spine and handlebars are tack welded together in this photo, but there is heaps more to do. It is all 316 stainless steel.
We turned up some alloy solid round bar to form these hawse pipes which will guide the sled over the descent line.
The throttle you saw at the top of the page will control descent speed, but as we will be hauling the sled up by hand I was keen on a deadman's brake. This is a brake that is sprung to stop the sled unless the diver has a firm hand on the handle bar. Here is that brake assembly (unfinished).
The rough looking alloy bit you see (above) is inside the stainless sled spine (below).
So; that is two weeks of mucking around shown in photos, and I guess there is another two weeks to go before the sled is finished and ready to test. I am not an engineer (or a freediver really) so things are going slowly. It is a fun project though.
Last edited:
If going down fast is fun than you might as well make it a no limits sledge and have some fun on the way up as well.
If it's for training equalisation on CWT dives than having a descent at the same 1-1.1 m/s speed as with CWT dives makes more sense.
If it's for training equalisation on CWT dives than having a descent at the same 1-1.1 m/s speed as with CWT dives makes more sense.
Beware! We tried a similar variable weight setup in winter in 2001. The idea was to do deep dives in winter. Mucking around with the sled setup wastes energy and you won't know it until it's too late. Our device only assisted the first 30m of descent (the super buoyant part when using a thick suit). My buddy used it, then I pulled it up from 30m (not a big weight either). I was next so I breathed up for many minutes -- thought I was well recovered from pulling the weight up from 30m. I dove to 54m and blacked out just after surfacing, despite have done 67m easily in the previous summer. As I felt totally fine during the variable descent, it occurred to me that during variable dives, you have no clue if it is a good or bad dive until its way too late. Like russian roulette! Subsequent attempts at variable have always had this 'random' effect with some close calls.
Using a lanyard on the sled has me a bit concerned. I am building it to minimise any snag points, but you can't eliminate them all and still have a functioning device.
Eric's post (above) makes it clear that a lanyard is required - but how to safely do it with a head down sled plunging into darkness? I think it was Natalia whose team decided against using a lanyard on the sled. A lanyard could help save your life if you B/O at -30m but it could cost you your life if it got tangled at -100m
Does anyone have any experience with those cyalume glow sticks below 100m?
Eric's post (above) makes it clear that a lanyard is required - but how to safely do it with a head down sled plunging into darkness? I think it was Natalia whose team decided against using a lanyard on the sled. A lanyard could help save your life if you B/O at -30m but it could cost you your life if it got tangled at -100m
Does anyone have any experience with those cyalume glow sticks below 100m?
Last edited:
Is that a knuckle duster and some seashells inside your weight? I hadn't thought of incorporating a knuckle duster into our sled..... until now.
WRT the 30kg retrieval: The ballasted sled will be around 20kgs, plus the base plate so a 25kg lift is more likely than a 30kg one I guess.
I am hoping that 5kg on the baseplate will be enough to keep the descent line tight - but we might need more. Testing in February should tell us that.