Sunday, March 24, 2013

Dash Panels and Switches, Part 1

When we first purchased the 340, one of the things I noticed was that many of the switches on the dashboard didn't "indicate" properly. To clarify - many of the rocker switches on the dash have small, built in incandescent indicator lamps. When the switch is turned "on", these lights illuminate, so the operator knows that circuit has been activated. But, over time, a couple problems inevitably manifest:

1 - Since the lights are incandescent, the do eventually burn out, leaving that circuit without a status indication.
2 - Incandescent bulbs generate a substantial amount of heat, and, over time, that heat degrades the plastic of the switch body. Eventually, the switch body may start to crack around the bulb, and the little bulb starts flopping around inside the switch.

So,  what to do? My answer is to replace the  bulbs with LEDs. Light Emitting Diodes solve both problems, since they have a life that is vastly longer than incandescent bulbs, and they generate far less heat. A couple suitable LEDs are here:

http://www.unique-leds.com/index.php?target=products&product_id=1953
http://www.unique-leds.com/index.php?target=products&product_id=1883

The royal blue one (1000 mcd) isn't as bright as the deep blue (2000 mcd), but either one will work quite well. They have basically the same dimensions as the incandescent bulb being replaced, so they snap right into place, and the O-ring seal around the bulb is still effective.

Now, if you look at the specifications for these LEDs, you'll note that the forward voltage is specified as between 3.0 and 3.6 volts (we'll use 3.3 for calculations). As such, a resistor is required in the bulb circuit, to drop the voltage into this range. Assuming worst case for a boat operating at roughly 14.4 volts, we see we have to knock (14.4 volts - 3.3 volts) 11.1 volts out of the bulb circuit for proper operation. Using Ohm's law, and the example of the Royal Blue LED (30 mA forward current), we have 11.1v / 30 mA (1000mA / 1 A) = 370 ohms. So, a roughly 370 ohm resistor needs to be in the circuit with the LED. At this current level, a 1/4 or 1/2 watt resistor is sufficient, and fits in the switch case with ease. These work fine:

http://www.mouser.com/ProductDetail/Kamaya/RC1-4394JB/?qs=sGAEpiMZZMuDPtTs5Gda260u%252bQsOF0S4HuXtl3e2gOo%3d

In the next post, I'll show an actual switch conversion - stay tuned!

7 comments:

  1. Dear Master Fab,

    I have a 2001 310 sea ray , I have see the beautiful work you have done. I am interested in replacing old stained carpet in cabin but t seems complicated. Is it hard to pull up carpet with the glue sea ray used to install it. Can vinyl flooring be use instead.

    Thanks
    Adam.
    drarnoldt@gmail.com

    ReplyDelete
  2. It can be difficult to get the old carpet up, but with patience, it will come up. You'll have to sand and scrape the old glue and carpet remnants off, but it's not that bad of a job. Once the subfloor is prepared, you can use a vinyl floor, if you like. But, you should consider resale value for any modifications you make. If you put down a floor that most people won't like, you might regret it, down the road.....

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  3. Thanks for your reply,

    I am friends with Greg , the guy you sold your last boat to. The wood floors in that cabin are very nice. It seems like a tough job because it seems all the carpet is connected. It isn't as simple removing just the floor (or is it?) the floor carpet goes in base board which goes into dinette area which runs right into the aft area. Any suggestion are appreciated

    Adam

    ReplyDelete
  4. It's not so simple - I recarpeted that entire boat, so it was easy to integrate the floor at that time. The carpet is hard to pull up, and an uneven surface is left behind. I levelled it with epoxy, so the floor would be flat. You do have to consider and plan very carefully....

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  6. Just wondering if you considered putting the same teak decking you did in the cockpit in the cabin as well instead of the cherry? I am thinking of pulling my carpet up on my 340 and going with the teak both in the cabin and outside on the deck. What are pros and cons you thought of when deciding what to put down. I do like the cherry and now considering that as well.

    John

    ReplyDelete
  7. I used Hickory in the cabin, not cherry. However, the teak decking I used in the cockpit is not suitable for interior use. It is an exterior grade PVC material. For your cabin, choose something more elegant such as Amtico or a real hardwood.

    ReplyDelete