February 1, 2016

Tidbit: AC electrical consumption when living aboard at the dock...

This is one of a series of brief, no nonsense posts that we call aTidbit: 
noun; small and [possibly] particularly interesting item of gossip or information...
The purpose is to share succinct posts about lessons learned, or things we use or do that work [or don't...] that are common to most of us boaters. 

The goal is to garner feedback from those of you having first-hand experience with a different approach/ solution/ product/ or additional useful information to share...  
We never assume what we are sharing is the ideal or only; it just seems to best suit our needs [and/or habits and/or budget] from our experiences thus far...
Sometimes these Tidbits originate from a topic of discussion on one of the forums we participate in, and this happens to be one: Link to original forum post [9-Nov-2015]
Note: The original blog post [below] has been inducted into Tidbits since it qualifies, but was published 3 years before we initiated the Tidbit series...
Since we are asked this question often, it made sense to post a more detailed response.

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Original Question from Cruiser's Forum:

Originally Posted by AFKASAP View Post

What size is your boat?
What significant appliances do you have running?
Is it winter or summer where you are?

How much electricity do you use per day [kWh/24 hr day] while living aboard (Longterm, not weekenders).

I am talking about comfortable living...

I'm assuming you are asking only about shore power AC consumption when at a dock full time.
Here is our off-the- dock consumption reply from Nov-2015, and here is an updated version published Feb-2019
We are not often at the dock full time, but sometimes spend weeks at a time during inclement weather in winter.

I generated some numbers by dividing my average electric meter bills by the KWH rates, so the are just estimates, and will be on the high side since I'm not subtracting fees and taxes also included on the bill.

Our worse-case usage is when we run electric heating at the dock in winter.

In winter [currently laying latitude 56° N in Wrangell, Alaska, with average temps around freezing] we average about 36 kWh/24 hr day.

Note: Our AC electrical consumption [when using our electric vs. diesel heat on shorepower]  can temporarily spike 2x or 3x during cooler weather spells [e.g., at 10° F (-12° C) and colder we can easily consume 100 kWh/day.]

On our 3 cabin, 2 head 43ft pilothouse ketch with 2 adults this includes running the heating side of one or more of the 3 air conditioners [maintaining an ambient temp of 20° C; 68° F] clothes washer/dryer, multiple laptop computers, water heater, battery charger, etc. Everything for creature comfort. [We've already proved in times past we can live without all the comforts... now-a-days we have nothing to prove...]

This is facilitated with a 50A 220V AC shore power source. [We only use the 30A 110V AC shorepower cord in summer- mainly for hot water and battery charging/equalization during brief stays in a marina.]

Away from shore power our AC electrical consumption goes down because we use a diesel fired heating system.

I don't have direct comparison figures for AC consumption when away from shore power, but can say we get by in winter running our 10kw generator for about 6-12 hours/week [depending upon solar and wind generator contributions] to keep our 900AH 12V DC (nominal) battery bank happy, run the 12VDC watermaker, make hot water, and wash/dry loads of laundry, etc.

It might also be interesting for all of us to compare what we pay per kWh. [We have our own electric meters at our slips here... i.e., electricity is not included with slip fees, but water is...]

Following are our hydro-power rates [US$] for Wrangell, Alaska:

Residential: Base monthly rate $8.00
0-300 KWH $.126 per kWh
300 -1200 KWH $.102 per kWh
>1200 KWH $.08 per kWh


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