[PSUBS-MAILIST] Emer Buoy brake and clear resin

Fri Feb 21 16:01:26 EST 2025

 Alec, you're correct, enough heat will soften and deform epoxy so the COB route may not be a viable solution. I suspect oil comp would work but then you're back to a solution that requires maintenance. Why aren't there any free lunches in this world?!?

Jon

     On Friday, February 21, 2025 at 11:19:23 AM EST, Alec Smyth via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  

 Jon I think you'll find the heat output of COBs is much more concentrated. Shackleton's lights are putting out 38K lumens, which come from a circle maybe 1" in diameter. The COB is mounted to the aluminum housing using heat conducting paste, and the housing has cooling fins. The glass is borosilicate to deal with the heat. Despite all this, I only run them out of the water for short periods. So I'm not sure, but I suspect the epoxy might degrade in the immediate vicinity of the COB, and the COB itself might be in trouble for lack of heat dissipation. The opposite approach might also be interesting, using an off the shelf light with a large number of smaller leds, if any can still be found. If you remember the Nuytco lights, they were like a big flat frying pan of small LEDs. On Snoopy I had some lights that were a little bit like that, a matrix of small LEDs. Unfortunately I don't have a brand or a link, but here's a photo.
Best,Alec

On Fri, Feb 21, 2025 at 10:31 AM Jon Wallace via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

 Hank,

A few things I've gleaned in my quest to find the ultimate off-the-shelf submarine light.

I've noticed that most off-road lights have moved to a tight spot pattern that is wide enough for a vehicle trying to illuminate 100-300 feet down the road but much too small/narrow for the 3-30 feet distance we would shoot for underwater. The Harbor Freight Road Shock Edge for example, at 3-10 feet distance has a concentrated spot diameter of about 10 inches with not much leaking light to the sides so totally useless for underwater use unless you wanted pinpoint light on a single seashell.

As you described, the reflector can be removed to convert the output into an omnidirectional flood however doing so results in a noticeable illumination loss because almost all these inexpensive off-the-shelf LED lights get their high luminosity rating by concentrating the light via the reflectors. Your use of a light bar is an exception because you're starting off with a 20k-30k lumen output with reflectors and removing them still leaves you with a whopping amount of light. The 4 and 6 inch round units don't have that same capacity unfortunately, especially those running on 12 volts. I did try the TigerLights without the reflectors (before expoying) and the intensity of the light seemed about as bright as a 75 watt house light bulb. A great omni-directional light pattern but just too dim. 

There's potential I think to build a hybrid using an off-the-shelf LED housing and replacing the PCB with a COB LED as described on the web site at http://www.psubs.org/design/lights/ that Cliff and Alec both use on their vessels. Installing the driver inside the vessel rather than inside the housing should make that a pretty easy conversion and result in a whole lot of light output. That will likely be my next side project.

Jon

On Thursday, February 20, 2025 at 12:22:20 PM EST, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Jon, this is great news.  When I make oil filled lights, I remove the reflector covers, the little cone things.  I find the scattered light is better than a beam.   
Hank
Sent from my iPhone

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