Cabling over water...

[AndyJones]

Hi guys. I am doing a gig near then end of the year, all the lighting will be on a lake. I have sorted out how to get power and stuff on the island, but I want to know how I can get the DMX back. I have though wireless DMX, or whether there are any other options?

 

1) I thought how about putting the DMX in a hosepipe? drawbacks are this would take ages, and I would need to resolder the ends

 

2) second idea, get loads of bottles, or bouys and atttatch them and float it across, there is no water traiifc so it shouldnt be a problem?

 

Any one else got any ideas or suggestions?

 

Thanks

 

AndyJones

[MarkPAman]

How wide is the water? I would have thought the cable would be waterproof, provided you do not need to join it underwater.

[the kid]

The one thing I see is "underwater" and "end of the year". Yes we are mild in winter but what will a frost/ice do to the cable? This is assuming that it will be evening/night and will be set up as such.

[bruce]

I have sorted out how to get power and stuff on the island,

 

How are you doing the "power & stuff"?

 

How far is it from the island to the mainland? 5 metres? a mile?

[Bobbsy]

Hi guys. I am doing a gig near then end of the year, all the lighting will be on a lake. I have sorted out how to get power and stuff on the island, but I want to know how I can get the DMX back.

 

Bruce is probably right to spot this (and I missed it first time through).

 

If, by this phrase, you mean there's already power out on the island then it might be worth asking if they laid a spare conduit you could pull through when they put the power in. Probably not...but it would have been the sensible thing to do!

 

Bob

[AndyJones]

Lighting will be done by a genorator that will be taken on site with a barge. although I am speaking to the client about possibility of putting in a permanent power box.

 

lake wise I think its about 30m across

 

Thanks

 

AndyJones

[mumbles]

It may be worth trying a pipe thats an inch in diameter, commonly used in ponds etc, like here. Either have it running up out of the water a few feet, with tape over the end, or with adaptors to reduce the size to a gland with jubilee clips (available from a pond shop), the cable could be kept dry inside the hose, which could then either run along the bottom if weighted, or would float.

[bruce]

A few thoughts, not in any particular order.... Disclaimer, I'm no lighting guru, but I know about cabling....

 

If, as you say, all of the lighting, and the gennie, are on the island, then why not put an operator there too? After all, someone will have to go out to power up (and babysit?) the gennie before the event... A set of radio cans, or even cueing via a mobile phone, would be cheaper than radio DMX...

 

or...

 

30m isn't very far. The BT phone line from my house to the pole at the bottom of the garden is longer. So stringing up a catenary wire, to support a DMX cable, might be an option?

 

or...

 

Why do you feel the need to protect the cable? is it from the water or from physical damage? I've seen plenty of data cables running through flooded basements, and the only ones we've had to replace have been the ones where the ends got wet.... Get some "disposable" cable - cat5 installation cable is dirt cheap and works fine - stick on some XLRs, and just chuck it in the water, keeping the ends dry! Make up a spare for a "belt & braces" solution. You can get "exterior grade" CAT5, but the main difference is the UV-resistance, not water-resistance, so it doesn't matter for this temporary application.

[leofric]

The lighting multicores used at festivals tend to be about 100m or so long. I've done plenty of outdoor shows where the multi has been dug into a shallow trench across grass. It has then rained very heavily, the talent has gone on stage, hundreds of people then dance on top of the said multi and in all the cases I've witnessed we have not lost a show due to the multi failing.

 

Even in winter you should not have any great problems provided you have a DMX cable long enough to lay across the bottom of the lake/river in one go and you keep any subsequent joins wheather proof. If you do use a long rn a DMX buffer may be of use depending on the kit you use.

 

It sounds a if it is going to be a bit of a pain regardless of which methord you use to run your cable. Remeber to run a secound one at the same time as a spare. We all know that water is not the only enemy of DMX data!

 

Sounds like a intersting job though, hope you enjoy it.

[Andrew C]

As said above, just chuck it in the lake. It may be worth weighting it so that you can be sure it sinks.

 

Now your real problem may come from the local wildlife... Cable looks a lot like a nice juicy worm to a dim fox or rat; this HAS caused me grief in the past! In short put spareS in if it is going to be left for any length of time!

[bruce]

In short put spareS in if it is going to be left for any length of time!

 

And make sure you test the spares regularly. There's a 50% probability that the backup link will get damaged first. If you don't test, then imagine how you'll feel when the main link fails and you think "no problem, I'll switch over to my backup...."

[b1nuzz]

yeah. did a gig a while ago on a lake. Just chuck it in. will be fine!

[Jivemaster]

BT have a technique to prevent water getting in (and nitrogen getting out) by filling the opened end of the sheath and all the interstices with a thin epoxy filler, they also use grease filled cable for the same purpose.

[AndyJones]

Well Thanks guys. I guess I shall just throw it in! It would be handy if I could find a way of keeping wildlife away.

 

I guess I could seaver one of the cables and put 240v down it :)

 

(sorry, feeling a little silly!)

[tivoliproduction]

how long do you propose keeping the cable in the water for? this could determine how many (if any) problems you get with the wildlife... all will be fine though, having worked in a cable manufacturing company for a few years we had to perform all kinds of tests...