OTS Comms for PSD

[tbzep]

I posted this in the OTS forum, then realized there have been no replies to anything there in all of 2016.

I have a few questions related to comms before we request bids. I've done a lot of reading, but most people only have experience with one or the other in each of these categories, not both. I'd really like to have input from folks that have experience with both aspects of each question.

1. Hot Mic vs Super Mic. From what I've read, Hot Mic is the way to go for better sound quality. It is my understanding that if we dive to any depth and remove the mask, the Hot Mic will be ok. However, if someone kicks the mask off the deck or boat and it drops 15 ft, the mic will be ruined. Is this correct? We practice removing the mask and going to alternate air regularly so we need to make sure the Hot Mic can handle it. Is there enough difference in sound quality to go with the Hot Mic or would a PSD be better off with a more robust Super Mic?

2. Comm rope. A few vendors I've looked at sell both 8mm and 10mm 4 wire comm rope. Is there any reason we should go with one over the other? We are a rural dept. and only average a couple operations a year at the moment. The bulk of the wear and tear will be from training. I don't like the idea of tying knots in it regardless of size, if that factors in the decision. We plan to use wraps instead of tying loops.

3. The Mk-7 is rated at 2w vs the large boxes at 20w. We plan to run 100-150 ft comm/tethers. Is the Mk-7 full duplex with all attached divers? Does the Mk-7 work well with Y adapter and 3 divers attached?

4. Wireless option. The upside is that we can use it without being tethered when required. Downsides, PTT only, and transmission quality. Our clearest body of water has only about 6 ft visibility on a good day, at least in the areas I've dived. It's about 55 ft at its deepest point. I've been deployed to farm ponds with zero visibility. How much will the thermoclines and water clarity affect the wireless units? What are other advantages/disadvantages to wireless? Are there issues with battery life or other issues with the mask units and topside gear?

 

[Jared0425]

I can try and answer a few. I believed I had mentioned this in the prior post so bare with me.

Our department has both wired and wireless comms. Our AGAs have the super mic and we have never lost one yet while diving and we abuse the heck out of some units. We have had them go bad for whatever reason, but that was after many many dives. My personal Guardian has the hot mic and I can't really tell the difference between the 2 nor do I know their true durability. I would not worry all that much about mics, if those are your only options go with what is cheaper.

Comm lines are not what they are used to be. We have the 10mm I believe and there is a quality difference between the older line and the newer lines. Our older comms have loops and knots that tie into both the diver and tender, and we have use them to sled and tow divers. The newer lines we have put adjoining crusix ropes onto both ends to reduce the amount of wear on the wire and we don't even consider sledding or towing with them. We have ruined 3 or 4 sets of comm lines due to us pulling the wires apart. So we run an actual stress line along the comm so we do not put much pressure on it. Regular diving patterns are fine as long as your not playing tug o war.

Wireless comms are great for short answers and knowing that your diver is ok. Conversation can be quite difficult to master, but has been done. That is our preferred method for towing and sledding now. We have not had any issues with thermocline, depth, or distance rather the divers are unfamiliar with it's operation and when to speak. Vis should have nothing to do with it's actual operation where we have 100ft of vis in the main lake or river to absolute zero in a pond or storm drain. We have had static issues over a certain regulator at the surface (Poseidon cyclone?) where it runs on the same frequency but once underwater the static goes away.

I hope this answers some of your questions.

 

[tbzep]

I remember you talking about the newer comm line quality. As for visibility having an affect on the wireless, what I read was that the sediment suspended in the water affecting visibility also affected wireless transmission quality. I was just hoping to get some clarification, no pun intended. Thank you for your comments. They will help us make our decision.

 

[tbzep]

My quote was approved and we are finally getting our comms! I'm currently taking the online OTS Guardian tech course and should have my Guardian running again in plenty of time to do some training and test out the new gear!

 

[tbzep]

The OTS comm gear has arrived. We purchased the Mk-7 unit with 150 ft comm lines and hot mics. Thanks to those who gave us the heads up on the weaker comm lines. We purchased rope wraps to use for attachment points instead of tying knots in the lines. If anyone has any advise for us as we get set up, we'd appreciate it. We purchased the Mk-7 to use with alkaline batteries because the NiMh option has a high self-discharge rate, especially if stored in warmer temperatures like our non-airconditioned bay.