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Under Water Lights

Discussion in 'Technical Discussion' started by BONDVOYAGE, Apr 19, 2009.

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  1. BONDVOYAGE

    BONDVOYAGE New Member

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    Hi I have a 55 Ferretti, been looking at installing under water lights for diving and just think they look great.

    I am getting mixed advise between LED vs HID lights... any one have experience or recommend one of the other?
  2. Capt J

    Capt J Senior Member

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    HID is definately the way to go. LED's aren't nearly as bright versus HID's and they don't seem to last any longer. IF water gets into either of them, the bulbs are toast anyways.
  3. BONDVOYAGE

    BONDVOYAGE New Member

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    Capt J, thank you... I was told that since the new LED's come with large Bars with multiple LED's in each they are as bright and since its low voltage they only need to cut a small hole in the hull to run the wires, do I need to worry about the cut holes with HID's???
  4. Opcn

    Opcn Senior Member

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    HID's seem to penetrate better, because of the more concentrated source of light, at least to human eyes. LED's will save you a little power, especially if you aren't trying for white light (blue or blue green, mono-, di-, or tri-chromatic). However you are going to need a pretty big wire to power a big array, which is what you will need.The array will be slightly larger with LED's, and if you want a wide diffusion rather than a light with a narrow cone of diffusion you will need diffusion optics on the LED's, which looses as much as 20% of the power.

    The failure mode is also important, with LED's you have the individual diodes blink out one by one, with an average lifespan of 25,000 hours, and a standard deviation of 4-5,000 hours in overdriven systems, like you would put on a boat, HID lamps slowly fade over the first 2500 hours, settling out between 60-80% intensity depending on what is actually in the lamp and tend to die at about 10,000 hours, however other components in the system can fail, the electronics involved in running LED's are a whole lot cheaper than those for HID's, but thats manufacturing cost not retail cost.

    If you want a whole lot of blue or red or bluegreen lights on your boat LED's are probably the answer, if you just want one or two white(ish) lights then go with HID, LED's still need a few years to be more economical.
  5. Capt J

    Capt J Senior Member

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    No, the thru hull holes that you cut in the hull of the boat are the same with both LED and HID. The electrical boxes used to run the HID's are usually mounted in very close proximity to the HID light (such as in the lazarette which is an open run to the HID light) so you shouldn't need to cut large holes throughout the boat, all you need is a basic power wire from the breaker panel to the HID electronic box.
  6. K1W1

    K1W1 Senior Member

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  7. Pascal

    Pascal Senior Member

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    LEDs are fine and are getting brighter with larger cluster.

    The most important thing in my opinion is how they are mounted and if they are serviceable in the water. I really dont' want to put in a big hole in the transom jsut for lights since there are alternative. unfortuntaly, when installing surface mount lights, most yards still insist on drilling a hole under the waterline, instead of running the wires up on the transom and penetrate above WL with a clamshell.

    if you run the wire above WL, this will allow you to unclamp the wire, unscrew the surface mount fixture and pull it up while in water if it needs replacement.

    and before anyone tells me LED lasts "forever", I have a 6 month old Abyss Light with 3/4 of the LEDS dead.
  8. Opcn

    Opcn Senior Member

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    What sucks, is that with .1 of a volt less potential your LED array would probably still be shining bright. LEDs have a sweet spot, at which they produce about 50 lumen's/watt, but when overdriven they enter unstable territory with more heat than light produced, if you stick an LED to a 9v battery it will be very bright for about a third of a second, then be gone, in order to get a little more power out of an array with out any added manufacturing cost they simply turn the voltage up a touch, they probably have a potentiometer in there somewhere and its probably a matter of a single turn of a small screw driver.
  9. K1W1

    K1W1 Senior Member

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    I am not sure about your particular install Pascal but I don't accept any U/W Lights where they cannot be changed in the water.

    We are using 16 of them on a current project, the exact light type is yet to be determined 100% but they will all be behind little glass sections in the hull
  10. Manny

    Manny Senior Member

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    Now that we're into this topic, I'm also thinking of putting underwater lights. I just want to know the cost of installing.
  11. Pascal

    Pascal Senior Member

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    instal cost depends on what you use and how you install them.

    If you have access to the transom from inside the boat, installing surface mounts is just a matter of running a power supply line to the transom, drilling a hole above water line to get the wire thru.

    on the outside, what you can do is fasten a piece of 3/4" starboard as a mounting pad for the fixture. 5200 plus a few screws will be fine. Then you attach the fixture to that mounting pad so that you can unscrew the fixtrue in the water if neded without having to worry about water getting into the screw holes. Run the wires up to the hole, seal and put a clamshell.

    With good access, its 1 to 2 hours per fixture at the most.

    obviously if you are to going to put some on the hull side, you can't really use surface mount, but the above will work well at the transom.

    When i had the lights installed on the 70 footer I run, it was a little complicated due to the hull shape. I had to have the yard build a custom mounting block. Unfortunately, we coudlnt' get the wires up above WL because we have a fuel tank in the way, so we had to come in behind the lights.

    then it got even more complicated when the yard failed to follow the instructions and apply sealant behind the fixture,. even though they were supposed to keep cooling passages clear. When they tried removing the fixtures, the wires ripped out on 2 of them. expensive mistake for the yard. Since we were ready to launch and i dind't want to wait a few days for replacement lights, I had them drill a hole in the mounting block so that we could coil extra wire in there, with a cover. Once i got the replacement fixture, I just dove in, pull the wires to the swimplatform, connected and sealed the connections then coil the wires back in the hole and screwed the fixture. simple. I can now replace those two without a haul out.

    unfortunately, the one that failed is the one they were able to pull out to remove the sealant, it doens' t ahve the extra wire coiled behind :(

    Attached Files:

  12. Capt J

    Capt J Senior Member

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    LED's CANNOT handle excess voltage. I made the mistake of plugging a 12 volt LED into a 24 volt outlet. It worked great for about three minutes, then about 3/4s of the bulbs burned out and the remaining 1/4 stayed lit. So if you have a voltage spike it will kill them. Also water in the housing will kill LED's also.
  13. Pascal

    Pascal Senior Member

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    abyss lights come with regulated power supply to ensure the right voltage is supplied to the lights, so voltage spikes shoudln't be a problem.

    btw...2 of the power supply that came with the 3 lights were DOA!! wasted a couple of hours crawling in the laz. checking the wiring, etc.... called them up, they replaced the power supplies.

    and dont' get me started on corrosion, even though I bonded the darn fixtures! the one that fails shows corrosion around the lens... the others dont.
  14. Opcn

    Opcn Senior Member

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    the LED itself is encased in epoxy, what probably happened is that the water in the housing shorted past a resistor and that bumped up the voltage. Presumably at some point in the future marine LED systems will hall have power conditioners like the high end land locked systems, and you will not have to worry about overpowering them. Something like a Flyback diode or a TVS is needed to prevent any damage from accidentally pluging in to 24V, although a system that leaks into the housing will still suffer shorts and failure.
  15. Yacht News

    Yacht News YF News Editor

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