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I am planning to free fall 180'~ over deep salt water with a raven 249. I have a 48 zp nonvented and 46 zp vented. I would prefer to use the 46 vented bc I rarely use it and it would be no big loss to me. I feel that the 48 would get the canopy over my head quicker, but I beleive the 46 would do the job as well. I am not sure who made the PC but it is in great condition, has 6 load tapes against the bias and the vent is a circle at the apex 4 3/4" in diameter. Does anyone see an issue with using this pc for 180' over deep water?

 
Relax. Why stress your self over this choice. How about none of the above?

Just D bag it. Problem solved.

Lee

I considered that, or static line, but free fall is just so much more exciting and completely doable.

180ft over water with either will be totally fine. Personally I'd use the 48 because PCs don't cost that much so i wouldn't care if it gets binned after the jump, but either will work. If you want to make it interesting go stowed or throw a gainer.

Over deep water either should be fine.

I'd personally use the unvented one, because the vent on the 46" makes it more likely to have a hesitation at zero airspeed.

Are the load tapes on it black? Or white?

they're white.

Large hole mesh on the vent?

Do you happen to have a photo of the PC?

Best guess would be that's a CR (pre-Asylum) 46 A/V. If that's the case, I'd definitely go with the 48".

Yes and it is white mesh.

I hear Tom is an expert on water landings.

Why not start with the 48 and then do it again with the 46? Personally, I would use the 48. 180 ft is doable, but damn, its gonna hurt if you have any hesitation on any part of the system.

Deep water just means its gonna be harder to find your body...

Yeah in all seriousness, if it were me freefalling it id use the 48. But my conservative side says to static line it

180' was based on online info. I went out there and lasered it today, it's more like 210'. With all that extra altitude, I think I may throw the slider on it. Now the question is do i use my 38 or my 32?

Jk, I'm still a little undecided, but that extra 30' does feel nice.

Hey Zach,

I have freefallen 210' with a 48" non vented pilot chute over
medium size trees and hard ground beneath them. Everything
worked fine: I had enough canopy time to turn left, flair, and
stand up the landing.

Hence for a jump from the same altitude over water I say go
ahead & use the 46 if you would rather that it gets the abuse.

Warning - I do not recommend newer jumpers try this!
Friends of mine on Facebook can watch the video here.

Why would you do that?

I have jumped 180' over hard ground using a toxic 46" vented and an OSP 285 and got a full 5 secs canopy. I also saw the same jump on a fox (260 vented I think) with a 52" non-vented and that also got a 5 sec canopy ride. Not sure I'd do it on a Raven though!

Do the people of this forum really have sarcasm detection deficiency?

 
It's not a deficentcy. It's a tollerance. It's like an old junkie that needs a huge shot of herion just to get off. Pluse, look at some of the shit people do now a days. He might be serious. I want all the details. Any body takeing notes for the write up? Nick was always on top of this shit when he ran the list. I bet he'd all ready have a file started by now. This could be even better then pilotchute guy.

Lee

Don't be stupid dude - a 32 is too small! You'd wan't to use at least your 38 if you're going slider up as the extra weight of the slider may cause a hesitation - and >200 feet is a long way down!

Exactly! Carry on.

did the jump, used the 46," went great.

i think you need to ask Ronald how to deal this problem

Pete. Here I am. I have done that over ground (sand) with a 42. I did like a second delay, hand-held and had 4 second canopy ride. Hell, I have even done a hop&pop with a 32 inch (brand new though, ZP) and I was under canopy in less then 4 seconds.

IMHO, a 46 and 48 will do just fine. The only difference between those PC's is the amount of drag in the air. The PC "stays" and you fall below it, leading to line-stretch and canopy deployment. So the smaller the PC, the more it will still go down, while still giving line stretch. And once your lines are fully stretched and the fabric is fully out, the canopy will open by itself. I don't really believe the PC opens your canopy.

Not sure if I am cursing in the church right now BTW, I plan on jumping church in my country quite soon

hahaaahhahah. I can trust on you allways. Fire to the flames Ronnie. Nice one. But there is lot of good points which i personally think are ok. so thanks for that Ronald :)

The purpose of the pilot chute is to extract the canopy (i.e. to move it from the container to line stretch). It does not "open" the canopy--airflow does that.


The overall opening sequence (from extraction to fully inflated canopy) has several distinct phases:

Pilot Chute Throw
Pilot Chute Inflation
Canopy Extraction
Canopy Expansion
Canopy Inflation


The PC size will have an effect on the first three parts of this sequence. In the sense that you think of the "opening" as the canopy expansion and inflation, then the PC has little impact on "opening." However, if you view "opening" as the complete opening sequence, then the PC definitely changes things.

Interestingly, as the PC gets larger, we tend to see the second phase (PC inflation) becoming less consistent, so that overall, with a larger PC, it is possible that the first three phases may take place in a _greater_ total time.

But there are a lot of things aside from PC size that can alter the PC's consistency of inflation too--presence or absence of vents, presence or absence of topskin load tapes, presence or absence of handles, type of mesh and number of tapes used on the bottom skin, and most importantly, technique used for folding the PC and technique used for throwing.

Once PC inflation has been achieved, a larger PC will create more drag and extract the canopy slightly faster than a smaller one, if all else is equal. But the PC inflation is generally a much larger component of the time required for overall opening than the time the PC takes to pull the canopy to line stretch.

The timing of canopy inflation and extraction can also change with PC size, and are generally less with a smaller PC (because the PC distorts the pack job less as it moves it to line stretch, so that the airflow hits the canopy itself in a more "ready to inflate" position).

The issue with using larger PC's is generally that they are less consistent (have greater chance for hesitation). This is an excellent argument for downsizing the PC, even on very low jumps (where consistency--avoiding hesitation) is usually a lot more important than getting the highest possible opening on the occasional jump where PC inflation goes as quickly as possible.

It's more important to reduce the range of possible opening altitudes to better plan the jump than it is to push the top of the range as high as possible (and leave the bottom end of the range low).

If you need to create the highest possible range for the opening, and still keep consistency, the first things you ought to adjust are your PC packing and throw technique. Those are a lot more important than overall PC size. In fact, the next things I'd personally adjust would be the venting of the PC (moving vents away from the apex, or leaving them off entirely). PC size comes a bit further down the list.


This is a whole lot more complex than just "what size PC do I use?" It's a big oversimplification to say that "larger PC's get you open faster" and it's probably not a safe oversimplification to make.