[PSUBS-MAILIST] Emer Buoy brake and clear resin

Sat Feb 8 20:13:41 EST 2025

 Hank,

I think you were correct the first time, 36-48 inch light bars are advertised with power ratings of 200-240 watts. Most double-A (AA) LED flashlights have more intensity than 200 lumens and even the good old sealed beam automotive headlights with tungsten filaments averaged 1100 lumens. I'm sure your light bar consumes a couple hundred watts, or close to it.

Jon

     On Saturday, February 8, 2025 at 06:38:41 PM EST, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  

  Justin,I think you are right on the money.  I miss spoke, I meant 200 lummen.  I did not have the heat sink on the board.  I simply submerged the board in casting resin and it failed right away.  Had I mounted it to the heat sink, I may have worked.  This will make for some real chaep reliable lighting.Hank
    On Saturday, February 8, 2025 at 02:16:17 PM MST, Justin Helland via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  

 Just to add my single anec-data point, I filled an off-roading light with epoxy and let it sit powered overnight and it seemed to work fine, although it was less powerful than Hank's 200W, I think it was 60W. But the off road lights have pretty solid housings with radiating fins, so maybe as long as the light has enough mass in the housing connected to a heat sink you might be okay. But I like Sean's suggestion of thermal epoxy, I bet if you could get the thermal epoxy to contact the LED board as well as the housing you'd be golden.
On Sat, Feb 8, 2025 at 10:50 AM hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

 Sean, I used casting resin, and not very thick, maybe 1\2 inch.  It would have been maybe 200 W  and it was submerged.  A test with a heat gun would be a good idea to start with.   You could make the epoxy extemly thin and try it with the thermal epoxy.   It only needs to seal out water.  Oil cmpensating has proven the components can handle pressure (1200 psi).   If Jon can make this work it would be fantastic.Hank
    On Friday, February 7, 2025 at 09:20:56 PM MST, Sean T. Stevenson via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  

 What epoxy did you use, and how powerful was the LED?
I wonder about the possibility of a two part pour, where a relatively thin layer would be poured only between the emitter and the lens using a clear epoxy like this:
https://mgchemicals.com/products/potting-compounds/epoxy-potting/clear-epoxy-resin/

...and then a separate pour could be done between the back side of the emitter / electronics and the housing / heat sink, using a thermally conductive epoxy like this:
https://mgchemicals.com/products/potting-compounds/epoxy-potting/thermally-conductive-epoxy/

    Would depend I guess on how much heat the LED package puts out, the temperature of the surrounding water, and the efficacy of the housing heat sink.  Was your test immersed?
Sean
 On Friday, February 7th, 2025 at 13:05, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

  Jon, I tested an LED light in epoxy and it bunt up pretty quickly.Hank
    On Tuesday, February 4, 2025 at 12:39:54 PM MST, Jon Wallace via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  

 Hello folks, looking for some suggestions.

1) Are you braking your spool of rope for the emergency flotation buoy so that it doesn't unravel during normal operations or do you find it unnecessary?  If so, can you describe how you are braking your spool?

2) I'm testing a set of off-the-shelf 12v led lights (4 inch round) and was going to oil compensate them but now I'm thinking about just filling the entire void with a clear non-yellowing epoxy.  I don't see the units as having any useful or serviceable parts upon failure regardless of compensation method so sealing them permanently with epoxy seems like a viable and perhaps less messy method in the long run.  The units would require approximately 1.25 inches (31.75mm) depth of epoxy to fill them and my only concern is what effect the dry epoxy will have on the light emanating from the units.  Any thoughts?

Jon
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