sailboat electrics

an area that often puzzles many...effective power consumption in todays cruising catamarans.
Can you be self-sufficient?

sailboat electrical

Green power!

‘Green power’ is climbing up the priority ladder to such an extent nowadays that some predictions of fossil fuel costs (scorned at a few years ago), are coming home to roost.

We have chosen to be proactive and endeavour to be as reliant as possible on solar power as we possibly can. Our yacht carries a few more items such as additional solar panels and batteries which will surprise some and be talked down by others.

The electrical system has Solar Panels developing sufficient energy to charge three of the four Batteries to provide 12Vdc power to the vessel. Before embarking on its make-up a few things need to be clearly understood.

There is a reason that the Electrical Trade is a 4-year course in most countries and one can't read a 2-page document and be versed on all-things-electrical.

For the 'purists-in-electrical-know-how’, this may not be for you as there are phrases and words used here which may not be strictly correct in the your eyes.

We also strongly recommend that a qualified electrician be used in the connection of your vessels appliances. Your State legislation may require certification for systems over a certain voltage (or amperage) and some Insurance companies carry caviats against DIY Electrical.!

"There is a reason that the Electrical Trade is a 4-year course in most countries"

Power Summary

Our Summary (guide only), and updated suggestions.

Read more

catamaran electrical


There has been a lot written about batteries and their advancing technology. Given this technology, ‘deep-cycle-batteries’ are said to be the choice of boat owners for many reasons.

AGM Batteries topped our list as they contain a fibre mat that absorbs the electrolyte acid and can therefore be sealed totally. They only need to be vented internally (not externally as with many others).

They have 4.5% more capacity than their gel type counterparts, allow a higher charging rate and have nearly twice the expected life.

They are however more temperamental on the undercharging and overcharging issues, making it very important to have some form of undercharging and overcharging protection built into the circuit.

marine batteries

Low Voltage Bulbs

Its here with lighting that you realise to what extent we rely on power and how easily, given some guidance, this ‘green-power’ can be developed, especially now with the onset of the LED /CCFL bulb age.

Lighting is all about Lumen and a Lumen is the measure of light against the power used (normally Watts). The more the lumen from a Watt of power, the better (or energy efficient) the bulb is said to be.

Read more

sailboat lighting

Correct DC Wiring

Many an amateur boat person has come unstuck at some stage in the electrical ‘black-hole’ regarding components or equipment not living up to their specifications. One buys a component expecting a particular performance, to find that it just does not happen.

Apart from the obvious of advertising, two other reasons are normally to blame:
1/ Inadequate component knowledge, and
2/ Incorrect wire cable and soldering.

Read more

marine electrical

Charging and Voltage Drop

Given technology today, 3-stage charging is the least that one should source.

Temperature compensation forms a critical part of correct charging and maintaining optimum performance of ones Smart Charger, especially in climates outside 20 – 30 degrees Celsius. Why this does not form part of the unit, is beyond us. As an extra, they can be bought and wired into the system, which is what we have done.

Read more

sailboat electrical

Understanding Solar Panels

Careful assessment of the efficiency of a solar panel and contributing power generation factors should soon ring a bell. Having said this, we planned worst case when sizing components such as the cabling and Smart Charger.

There are unusual factors such as cloud-edge-effect that can momentarily spike the generation system every now and then, and these worst case buffers need to be built in.

Read more


Solar Panel Make-up

The electrical items (from the Electrical Matrix) were then placed into AC and DC power requirement sections.

Our excel spreadsheet 'planning plot' calculated that we needed 111 Ahrs (excluding the desalinator) or 151 Ahrs (including a small 12Vdc electric type desalinator), to cover the type of electrical set-up we needed for each day (over a 24-hour period). And yes, this figure is relatively high when compared to other yachts. We say, “our boat not yours”.

Read more

blue sky solar charger

How many Busses should you have?

We ended up with 5 main Busses:

Hot Battery Bus (or HBB) - linked directly to the battery and can be left on to certain essential switchable components at all times,

Main Bus ('THE MAJOR BUS') - where all the yachts DC electrical busses and DC electrical cables have their source – except the HBB above,

Starboard Distribution Bus - distribution point for all DC starboard electrical,

Port Distribution Bus - distribution point where a majority of the port electrical DC, Nav bus power, radios, hot water system and ships pumps have their source, and

Navigation Distribution Bus - distribution point for all the navigation gear.


Bus Bars and Busses

So, what is a BUS BAR? A BUS BAR is a point of distribution, normally made out of a good power conductor, most commonly copper. Units are sometimes made from copper pipe however, in all instances, the greater the surface area for heat dissipation, the better.

Read more


Power Requirement Matrix

So, where do you start?

A 'Power Requirement Generator' (a simple Excel spreadsheet we made) allowed us to quickly change and modify (or more correctly, teach us) how to conserve energy and make best use of the power throughout the various parts of the day.

More importantly, the Electrical Matrix (another Excel spreadsheet with a list of appliances with their associated volts, amps and wattage), gave us the power needed to meet our newly planned energy budget during various times of the day.

Want to

yacht electrical

Replenishment Risk

Replenishing energy (electricity) purely with proven techniques of small vessel power generation, comes with some form of ‘calculated risk’. A genuine decision has to be made on what we were going to use the boat for as this dictated the requirements and then build that into this 'Replenishment Risk'.

The most common forms of power generation on yachts include solar panels, generator/s (separate portable generator units), alternators (units making power from available and/or separate motors, usually the motors powering the boat), wind generators and water generators.

Read more on what we think...

sailboat solar panels

snapshot video

diy multihull electrical

If video says 'No access', empty your device 'cache', then 'refresh'.

Please consider SUBSCRIBING TO OUR CHANNEL, it really helps us get to a wider audience.

Thank you in advance.

© Copyright 2009-2024 - All Rights Reserved