Here is an off the shelf 270W PS that I am going to use to feed a
regulated 12VDC bus in the nav station:
http://www.powerstream.com/Produz10.htm
If you really want to DIY check out
http://www.powerdesigners.com/InfoWe...converter.shtm
David wrote:
 If you have a design, I would really like to see it.
 I am trying to get a design for a 12 volt DC to 12 volt DC regulated power
 supply. The design is to provide 12 volts DC + or - 5% output from an input
 of between 8 volts and 16 volts DC.
 The purpose of this is to run a computer in a sail boat. The battery voltage
 in the boat may vary from 8 volts to 16 volts when it is charging.
 I currently have an ATX computer power supply that runs off 12 volts DC, it
 provides 3 and 5 volts nicely, but the 12 volt rail is actually the input
 voltage. So, when the input is 12 volts all is well, if it goes high, well
 that could be a real problem, and if it goes low, the computer will shut
 down. If you can help it would be much appreciated
--
Glenn Ashmore
I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at:  
http://www.rutuonline.com
Shameless Commercial Division: 
http://www.spade-anchor-us.com