DIY Adjustable Buoyancy Devices for Underwater Camera Strobe arms

A little story about how I came to make my own adjustable floats for my underwater camera rig, along with some instructions of how to make them yourself ūüôā You’re welcome.

This little project started after a foolish omission while ordering an additional strobe for my Sony A7R II Nauticam housing.¬† I have 2 Nauticam carbon float arms¬†(costing upwards of 75GBP)¬†that I attach directly to the camera housing (interestingly one is now leaking ūüė¶ ).¬† Even with this, the camera is quite negatively buoyant, although not hideously so.¬† I ordered the additional (Sea & Sea YS-D2) strobe, and dual sync cable, in a bit of a rush and last minute (typically) and completely forgot to consider that I really should have bought at least the StiX high density foam floats.¬† So, with 3 days before I left on a 5 month work trip to Timor Leste I had to figure out how to DIY a solution.

After hours of searching discussion groups and diving forums for inspiration I only came across the use of specialised 95km/m3 foam (such as Aircell or Divinycell H100, and I wondered if any of the Kingspan products would work), which I had to order (so not a convenient solution).  I considered using kick floats, yoga bricks, and even the base of cheap body boards (all of which were shot down when I searched more forums, mainly because the high density closed cell foam used was around 65kg/m3, and for which the general opinion was they were useless beyond 5-10m).  Pool noodles being the least useful of all the options, despite a number of ingenuous souls heading into the blue with such colourful thoughts of success.

About ready to give up, the thought occurred to me that all the carbon float arms are is a sealed tube of very rigid material.  So why not try and find something similar, or find a way to recreate such a thing.  Not finding much in the way of suitable products that I could re-task for the job, I thought why not use some PVC piping, with some kind of seal at either end.

It turns out that too isn’t an easy task…¬† The principle issue was finding a suitable cap.¬† “Stop ends” are a thing, albeit a bit of a rarity.¬† Turns out there’s not such a demand for these items.¬† A browse of the ScrewFit website showed that there wasn’t enough in stock of them locally.¬† I needed four, for two floats.¬† In the end B&Q was the answer, and, to a large part, the help of Steven (a fellow diver of all things!).

Having gotten some foundational ideas from my dear friend, and builder, Paul I headed to B&Q to figure out what they had.  With help from Steven, my shopping list was (just under £20):

The concept was simple.  The two Access Plugs (which have a washer inside the screw cap) would form the top and bottom of the tube.  They fitted into two couplers that were, in tern attached to each other via a short length (25mm) of pipe.  It should be noted that the process would be much tricker on short strobe arms due to the amount of material needed to be removed from the coupler, and thus the area available for bounding.

Okay, not so clear.  Step by step then:

IMG_2623
This is the final product (a little messy but you get the point)
  1. Preparation

    1. Remove the labels from couplers and plugs and throughly clean with rubbing alcohol, surgical spirit, or white spirit to remove any grease or the glue from the stickers.
  2. Measuring to fit strobe arm:
    1. Check the length of the strobe arm, measuring about 10mm below the ball joints
    2. I use 200mm arms and so I needed to take 5mm off only one end of all the couplers (for longer arms this may not be necessary).
    3. Cut off this excess with a angle grinder or junior hacksaw or band sander (take care!).
    4. Clean up the rough edges with a knife and sand down rough edges.
    5. The cut is side A
    6. The uncut end is side B
  3. Creating Capped Couplers & setting them aside in pairs for final assembly
    1. Pair each of the Couplers with an Access Plug.
    2. Using a reasonable amount of solvent cement on the stem of the Access Plug, glue one plug into side B of each of the couplers
    3. Let them set for 5 mins
    4. We will call these capped couplers.
      1. Label two capped couplers #1, and two #2
      2. These are capped coupler pairs that will be bounded together using a short length of the waste pipe.
  4. Creating the connecting waste pipe to link the capped couplers
    1. Using capped coupler pair #1
      1. Measure the highest point of side A from the midpoint lip. Do this for both capped coupler (length x and y).
      2. Length x + y will give you the total length of pipe you need to connect the capped coupler pair.
      3. Label the pipe #1
      4. Repeat this for capped coupler pair #2.
      5. Label the pipe #2
    2. For each capped coupler pair, cut the desired length of pipe from the 3m length.
      1. Remove the rough edges with knife and smooth them with sandpaper.
      2. Clean this length of pipe of grease.
  5. Final step to make sealed float:
    1. Remove the screw tops from all capped couplers (preventing compressed air causing problems when bounding the couplers together).
    2. Using capped coupler pair #1 and Pipe #1
      1. Apply the solvent cement to the inside of side A of one of the capped couple pairs down to the midpoint lip.
      2. Insert the pipe into side A and allow this pipe/capped coupler set to bound (5mins)
      3. Apply the solvent cement to the inside of the other capped coupler of this pair (#1)
      4. Slide the other capped coupler onto the pipe protruding from the first pipe/capped coupler set and allow both set for 15mins.
      5. Screw on the caps tightly and you now have one buoyancy aide!
      6. Repeat this section to create the second buoyancy aide.
  6. Fixing the buoyancy devices to the arms was done with thick zip/cable ties.  I should trim the ends off but was still testing the set up.
  7. An additional issue I had to resolve was to keep the screw tops of the stop ends off the strobe arm so I could adjust the buoyancy if I wanted (not that I really needed to). So I taped rolled up plastic bags cut to measure to one side.  This created a cushion that pushed the DIY buoyancy device off the arm.
  8. I wouldn’t recommend the duct tape as it stinks a bit it it stays wet for any length of time. ¬†Regular scotch tape would work, and to get really fancy you could spray it black at the end.
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