DIY UNDERWATER CAMERA FLOATS & STROBE ARM FLOATS

camra-floats A heavy underwater camera rig is something that can really put a strain on any underwater photographer. One of the easiest solutions to this problem is to use foam floats to neutralize the camera's buoyancy underwater. But buying commercial brand foam-floats can be expensive, and they may not fit your particular setup without buying additional accessories such as special strobe arms. Before you know it, a simple set of foam floats can add up to an expensive proposition.

The good news is that it's pretty easy to make your own underwater camera floats, and probably for less than it costs to buy them pre-fabricated. For example, I was able to build a complete set of floats for 2 camera rigs for around $40, not including my time invested.

The basic materials you will need:

  • Divinycell* Foam (or other PVC closed-cell foam)
  • PVC cement
  • Plastic "Fusion" spray-paint

The basic tools you will need:

INSTRUCTIONS:

The following instructions describe how to make your own set of underwater camera floats for scuba diving. Depending on your DIY skills, you may want to incorporate some of your own methods. Hopefully this guide provides you with a good set of guidlines to work from.

  1. Calculate the underwater weight of your camera rig.
  2. Choose the best kind of foam.
  3. Calculate the exact amount of foam you need for perfect neutral buoyancy
  4. Choose a custom layout and cut the foam.
  5. Do a test run.
  6. Clamp and glue.
  7. Finish & Spray.

STEP 1: CALCULATE YOUR CAMERA'S UNDERWATER WEIGHT:

Before you build your foam floats you need to know exactly how much dead-weight you need to lift when your camera is underwater. (The following examples assume an underwater camera weight of 2.4 lbs; or 38.4 ounces)

One easy method of weighing your camera underwater is to submerge the entire camera housing in a large container while attached to 2 strings. Tie the strings to each side of your housing so it can be suspended underwater. Tie the tops of the strings about 1 foot apart on a wooden dowel. Then slide a digital scale under the dowel and take the reading. Don't forget to subtract the weight of the wooden dowel.

It's a good idea to install the camera in the housing and attach any strobe cables and special lens ports that you plan to dive with when you weigh the rig, so that your weight measurements are accurate.

If you plan on using my Buoyancy Calculator, you should take the measurement in ounces (oz).

Using the RubberMaid Method.

STEP 2: CHOOSING THE BEST FOAM TO USE:

Ideally you want a foam that is durable, light weight and that also has excellent buoyancy A rigid closed-cell PVC type of foam is perfect for this, and your camera will maintain a constant even buoyancy at any recreational diving depth.

Soft foams such as Polyethylene (AKA pool noodles) will compress and lose buoyancy as you go deeper. That makes it a poor choice of foam if you plan to do a lot of diving with your camera deeper than 35 feet or more.

One type of closed cell PVC foam goes by the name of Divinycell H100. Divinycell is commonly used in surfboard, winsurfer, and boat construction so it is a perfect material for this type of application. But any similar closed-cell PVC foam should work equally as well.

PVC foam is very rigid, similar to soft wood, yet it is lightweight and provides an optimal amount of lift. It can be bought in different densities depending on the application. The 6 lb per cubic foot variety works well for this project because it provides a very good combination of durability and lift.

This 12" x 10" x 1" piece of foam cost about $18, purchased online. Less than one full piece is needed to provide the 38.4 ounces of lift needed for the camera rig in this example. Unless you very confident in your DIY skills, you might want to buy more foam than you really need, to allow for mistakes.

STEP 3: CALCULATE AMOUNT OF FOAM NEEDED

LIFT NEEDED (in ounces) divided by LIFT PROVIDED (in ounces per square inch of foam) = TOTAL CUBIC INCHES OF FOAM NEEDED.

You can do the conversions yourself or feel free to try my Buoyancy Calculator.

If you want to learn more about how to do your own calculations, check my Archimedes' Principle page.

STEP 4: DECIDE THE LAYOUT & SIZES

Okay, here's the creative part. You need to figure out the best way to distribute the foam on the camera rig so that it doesn't get in the way when you go to use it. Consider putting the biggest foam pieces on top, near the strobes, to keep the camera rig right-side-up while underwater. Too much foam on the bottom of the camera housing will make it flip upside down when it's underwater.

Rough cut the foam with a jig saw or miter saw. You can do your final trimming and finishing later on after testing. The foam is very similar to working with soft wood, so carpentry tools work well.


Example:

As mentioned above, my camera rig weighs 38.4 ounces underwater. Using the Buoyancy Calculator I calculated that 71.4 cubic inches of foam is needed to make the camera rig neutral underwater.

The layout I have chosen to go with consists of 4 floats (two floats on each strobe arm). There is a total of 71.98 cubic inches of foam all together. (I gave myself a little bit more foam than I needed to compensate for trimming and hole drilling when I finish the floats):

LENGTH
WIDTH
HEIGHT
QTY.
TOTAL VOLUME
LIFT PROVIDED
3.75
2.6
2
x 2
39 cubic inches
20.98 oz
2.85
2.85
2
x 2
32.49 cubic inches
17.48 oz

Tip: If you want to be super accurate with your measurements, make sure to take into consideration any holes that need to be drilled into the foam for mounting them on the strobe arms. For example: I needed to drill a 3/4" hole in two of the floats in order to fit them on the strobe-arm bases. I calculated π(r)^2(height) to figure out how much foam will be lost when the holes are drilled. It turns out about 2.5 cubic inches of foam is lost from drilling the mounting holes. That's equal to losing about 1.3 ounces of buoyant lift.

STEP 5: DO A TEST RUN

You can test your cut pieces by strapping them together with some rubber bands and strapping them to your camera housing. Submerge the rig in water again and dial in your perfect amount of foam.

cm-foam cam-strap cam-weigh

STEP 6: GLUE THE FOAM

Since this foam came in 1-inch thick sheets, you may want to glue them together to make 2-inch thick sandwiches. Regular PVC cement works perfectly, and it forms a very permanent bond. Use some C- clamps to keep the pieces tight and in place as the cement dries. Once the sandwiches dry they can still be cut and molded. After the foam gets painted you will not be able to see any seams.

STEP 7: FINISH & SPRAY

After the glue has set (about 24 hours) it's time to do the final details. Drill any mounting holes that you want and do your final trimming & sanding if you wish. You can easily cut and glue additional pieces of foam to your floats without any problems. So if you accidentally over-cut your foam you can simply glue a little bit more foam to your floats until you get it just right.

As you see in these pictures (below), I used two different mounting styles:

1. For the middle of the strobe arm I routed out a groove in each float which slips easily onto the middle of the strobe arm, and then a cap snaps on top to hold it together. I use a thick rubber band, to reinforce the caps when I dive. (Hint: The heavy-duty rubber bands used to bunch broccoli in the produce section at the grocery store work great!)

2. For the floats at the base of the strobe arms I simply drilled a 3/4" hole in each piece of foam which slips right onto base of the strobe arms.

When you are finished fabricating you can then spray paint the floats with a specialized plastic paint such as Plastic Fusion or similar brand. These paints will bond to the PVC foam very well and give a finished look to your floats. Over time you will get some scratches and dings from normal wear & tear, but these can easily be touched up with another spraying.

The final product is light weight and durable, and should last many many dives. You will finally be able to enjoy taking underwater pictures without having to struggle with a heavy camera! And you saved money and DIY.

float2foam1float3

camra-floats

If you have any questions or comments about this project, feel free to contact me. Email: diver@scuba007.com

If you have any pictures of your project I would be very interested to see them!

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