Working on the boat - wiring always seems to be a bugger when you buy a used boat.

 

Greg has been working for almost three weeks straight now and I can't get him to take a day off. He says the wiring on the boat is driving him crazy; he can't just ignore it. The other night in frustration he wrote this to a friend. Perhaps it will be useful to someone faced with the same problem - or it will just illustrate how frustrated Greg is.

"This boat had 3 solar panels and three separate charge controllers, one per panel. For whatever reason one panel was uninstalled and tied to the ceiling of the salon. I watched the two installed panels turn each other off one morning after I consolidated the battery bank. The first panel that got sun would start charging and raise the battery voltage, but only put out 4 amps. The second controller decided the batteries were therefore charged and would not pass any current. Then the mast shaded part of the first panel and the process would reverse. Never, EVER did I get the combined output of both panels. (ARRGH!) So I ripped out three charge controllers that cost the last owner $120.00 apiece and put in a single MPPT controller from BZ products ($149.00.) It can run all three panels simultaneously. With two panels working I got output at 9:00 a.m. and it

climbed to over 7 amps then floated the batteries before noon. Encouraged, I got out the third panel. It mounts on the dodger and uses a sort of trailer plug for the connection. Once installed it produced nothing! I started unwrapping taped-over wire and discovered 5 butt connectors on the negative wire (plus the connector) and 4 more on the positive wire. A pair of butt connectors was used to add one inch of wire!!???

 

I could measure over 19 volts coming off the panel but at the controller end I was only getting 7.6 volts. Apparently someone told the last owner that it was important (read CRITICAL) to match positive/negative wire lengths on DC systems (--??.) This can be true in high impedance systems and HF radio but really a bad idea on DC. Here are the rules I’ve internalized for DC wiring:

1) Never use any longer a wire run that necessary. A “run”means both sides, negative and positive (and these don’t need to be the same length).

2) Create a ground bus system. Use a run of big (really BIG) wire from one end to the other and connect everything to it.

3) Download a wire size calculator spreadsheet and live by it. If it tells you that you should use # 8 wire then DO it!

4) Connections cost you 2 volts/connection after these get some oxidation and these will in a boat (unless the wire size is so big that it makes no difference), so don’t splice wire and crimp/slder and heat shrink connections if at all possible. Especially splices!

5) MAKE THE WIRING SIMPLE. Don’t use paired cable if you can get shorter runs from your ground bus,

6) label EVERYTHING.

Incredibly, there is lots of wire on the boat, but if you want a piece smaller than #8 you must salvage it from some unnecessary installation. We have a large carry bag full (50 lbs or so) of cable up to 2/0 (11 feet in black and red just in case) and enough short connectors of various lengths to create a bank of 30 batteries or so (of course the boat might have trouble floating!.) Just removing the unnecessary solar wiring produced about 24 feet of #10 wire. But try to find a piece of #12, hmmm! Nothing happens in Mexico between Xmas and New Years and that means the chandlery is closed. I went to my favorite ferreteria and asked for “connectodors para cable” and got ushered to the back where I was shown “Todos” where I proceeded to buy them out of # 10 eyelets and spades. The boat comes complete with enough 18/22 and 16/14 “connectadors” and butt connectors of all sizes to stock Hardware Sales in Bellingham (best hardware store in the Pac. NW), but try to find a #10 eyelet for a ¼ in. stud – well!

Thanks for letting me blow off steam. Tomorrow I start plumbing the water maker because we’ll be getting our brackets and pulley soon (well manana, you know – in the next two weeks)."  Greg Hurt

Today Greg is working on installing the watermaker. I have to occasionally refocus him as he gets distracted by some new wiring enigma. Of course the membrane won't fit where he had initially planned to put them but it looks like he may have come up with a better plan. Its become obvious to me now, after two installations, that almost anyone can build a watermaker. However, designing the necessary mount for the pressure pump will probably throw most people. Fortunately for us, Greg is skilled at design and creating the engineering drawing for the machinist.

The skies were cloudy this morning and now the wind is starting to howl so its time to pack it in for the day.