• Welcome to ScubaBoard


  1. Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.

    Benefits of registering include

    • Ability to post and comment on topics and discussions.
    • A Free photo gallery to share your dive photos with the world.
    • You can make this box go away

    Joining is quick and easy. Login or Register now by clicking on the button

1st time deploying DSMB underwater. Need feedback on issue.

Discussion in 'General Scuba Equipment Discussions' started by Fastmarc, Jul 14, 2019.

  1. Fastmarc

    Fastmarc Just drifting along... ScubaBoard Supporter

    # of Dives: 200 - 499
    Location: Kingston, Jamaica
    1,292
    248
    63
    i have been diving with DSMB for years and have had to use it once on the surface. I’ve realised that I need to practice deploying underwater, but my diving circumstances has not allowed me to do so as yet. Yesterday it caught up to me and I had to.
    My dive guide inflated his (I think 4ft) at the surface attached to a reel and we descended. The boat was anchored, but there were not sure the anchor was holding, so just in case the captain could follow us with the his SMB.
    We checked the anchor and it seemed secure, so off we went. When we returned the anchor was still secure, but the rope was on the bottom and no boat. He signaled to me to deploy mine and went about securing his to anchor rope. Having read and watched enough videos on deploying, I knew what to do, so I slowly and thoughtfully went about it. I have a 6ft version. I did an ok job getting it off, but know I need to practice to get it smooth with less effort. There was a little current and once it was at the surface it was like holding on to a kit. I had to let it out more and more to maintain depth. What the hell. After the guide secured the rope to his, he went to check the anchor. This is when I encountered the 1st issue. When I went to follow him, I could barely move, such was the drag. I was basically just ascending more than moving forward. I had give more length to maintain depth and move. It took a lot of effort to move. Eventually we started drifting and ascending. I wound up my spool and did the safety stop without much issue.
    When we got onboard I noticed the DSMB was filled with a lot of water. It seemed fully inflated, but it seemed half was water. How did that happen?
    I fully inflated after when I was washing and no leaks. Could I have caused this some how?
     
  2. RyanT

    RyanT Solo Diver

    # of Dives: 500 - 999
    Location: Maryland
    1,664
    1,286
    113
    As you discovered, they're not designed to tow. As you were swimming with it, you were pulling the open bottom into the water column/waves and that pushed water into it. It also generates a huge amount of drag. If you're drifting with it, its normal to have to let out some scope in wind and currents. Unless the wind and currents are doing something funky though, you should be able to drift along easily at depth without letting out a tremendous amount of line. When drifting with the bag, it's best to remain in good horizontal trim. That'll allow you drift along with the bag better when the wind is blowing it.
     
  3. The Chairman

    The Chairman Chairman of the Board

    # of Dives: I just don't log dives
    Location: Cave Country!
    54,803
    21,827
    113
    That's called "scope" and 3 to 1 is adequate for a boat in fairly benign conditions.

    SMBs are subject not only to current, but also to wind. They can be just as hard to tow as a dive flag.
     
  4. Edward3c

    Edward3c Instructor, Scuba

    1,327
    516
    113
    Deploying a DSMB is a skill that needs continuous practice. It’s not something you learn to do once and forget - but lots do. I put my instructors through mid-water deployment practice a few weeks ago.

    If you used your regulator to inflate the DSMB, as air goes in you also input water. Hence why I have a low pressure nipple on mine.
     
  5. Fastmarc

    Fastmarc Just drifting along... ScubaBoard Supporter

    # of Dives: 200 - 499
    Location: Kingston, Jamaica
    1,292
    248
    63
    Ah, that must have been it. I was really trying for a while to swim with it and I must have been forcing water up it when doing so. I was going no where fast.

    Once I was drifting it was much better. I was able to stay horizontal and I was reasonably pleased with how I wound it up while ascending and stopping at the safety stop.
     
  6. Fastmarc

    Fastmarc Just drifting along... ScubaBoard Supporter

    # of Dives: 200 - 499
    Location: Kingston, Jamaica
    1,292
    248
    63
    Ok, learning more. I saw the angle of the line, but of course the length increased when I tried to swim with it. Once I stopped and started drifting I had to wind up the excess.
    It was choppy/rough. The guide’s smb was shorter and narrower with no open end. It didn’t give him any resistance while towing which is why is was ‘what the hell...’ when I was trying to do the same. I was initially thinking of using mine for that purpose, but clearly that’s not its purpose.
     
  7. Fastmarc

    Fastmarc Just drifting along... ScubaBoard Supporter

    # of Dives: 200 - 499
    Location: Kingston, Jamaica
    1,292
    248
    63
    Very true and I do plan on getting some in.

    I used the nipple. Removed the reg with my left while holding the spool and DSMB with my right. I gave it a 1st blow to straighten it out a bit then a big second blow. I think I may have put a little too much in the 1st as I remember having to kick down a bit after the second then releasing. Really need and want to practice this some more.
     
  8. Fastmarc

    Fastmarc Just drifting along... ScubaBoard Supporter

    # of Dives: 200 - 499
    Location: Kingston, Jamaica
    1,292
    248
    63
    I just realised that my previous plan to use a particular shore dive to practice this may not be a good idea since I would have to tow it in to shore.
    I may need to buy another DSMB.
     
  9. The Chairman

    The Chairman Chairman of the Board

    # of Dives: I just don't log dives
    Location: Cave Country!
    54,803
    21,827
    113
    A good indication of wind. The choppier the windier. The taller the waves, the more wind you are in. On top of that, both wind and waves are a great indication of a surface current which may or may not match deeper currents. The boat's anchor line is always pointed into the surface current and wind which (you guessed it) may or may not match deeper currents.

    As a general rule currents are faster on the surface or in the middle, and slowest on the bottom or sides. In the ocean, sides are referred to as "walls". On the bottom you can escape currents almost entirely by ducking into the valleys and sticking to the lee side of structures. Of course, you can't escape that string in your hand if you're towing a flag or smb.
    SMBs are rarely needed for diving from a static boat. You should stay close to the boat and it's flag. SMBs are more suited to drift dives where you don't have to fight it: just ride it. Of course, you can train on it anywhere and learn it's limitations.
     
    Fastmarc likes this.
  10. jgttrey

    jgttrey Barracuda

    # of Dives: 200 - 499
    Location: Houston
    444
    434
    63
    If you really want to practice shooting bags, find an old one and punch a small hole in the top. It'll shoot fine, but you can wind it back down and do it again and again without trashing your ears going up and down to fetch it 10 times.

    Just make sure to mark it as "practice only".....
     

Share This Page