Thursday, February 20, 2014

on doing your own math...

A real good example of why things are so screwed up, space on a budget, and about something really dumb on the internet...

Back when we were building the first Loose Moose, a friend of ours was building a strip planked design and one of his favorite words was "robust"... The boat in question was a pretty design and the designer had specified strip planking with glass on the inside and outside, a light but strong construction.

Pascal thought it was not quite robust enough so he cold molded another four layers of 1/4" mahogany and about tripled the glass schedule... Getting into icebreaker sort of scantling territory. To say that the boat was quite down on its lines was something of an understatement and, last I heard, Pascal was looking at cunning plans for conning towers and periscopes.

I mention this because overbuilding is such a common thing around amateur made or rehabbed boats that it's become something of the norm and no one ever seems to question just how much is too much.

The other day I looked at the original schematic for our boat's electrical system. I had something of a eureka moment trying to sort out what-in-holy-hell had become of my electrical system as it had become both over-complicated as well as robust to the point of silliness.

Now, of course, a boat built in 1969 did not have the sort of electrical usage and amp draw that is common today. Comparing the then and now schematics started to make me wonder if,  just maybe, somewhere previous owners had gone way overboard...

So, I started looking at what sort of amp draws and electrical system "So It Goes" really needed to try to sort out if the evolution from a system using 4 AWG wire to 00 AWG was actually merited. For a quick look as the sort of wire you should be looking at you need to check the 2% voltage drop chart...


To make a long story short... It wasn't. Now, at this point I have to warn you that this is what works to get sufficient power where needed, is safe for our boat, and electrical system loads... YOU have to sort out what works for yours.

The point is our system was seriously overkill and whoever made those decisions did not do the math to figure out what was needful but went with the bigger is better approach or did a  Pascal and went all robust on its ass.

Now, while 4 AWG wire will work on "So It Goes" it has less safety factor than I'm comfortable with so we went with 2 AWG which, while still overkill, is what I consider to be a sensible compromise that results in a bombproof system without going to a crazy extreme.

The advantage is it gets a lot of weight surplus to requirements off the boat, makes working on the electrical system easier, and saves us a lot of money in the process because 2 AWG is a fraction of the cost of 00 AWG.

The moral to this story is simply to do your own research and math. Sort out what you actually need not relying on the fact that since-someone-else-is-using-battery-cable-of-a-certain-size-that's-what-you-need logic.

Listening to Lucius

So it goes...