Electrical draw of autopilots? - SailNet Community
Reply
 
LinkBack Thread Tools
post #1 of 24 Old 11-10-2009 Thread Starter
Junior Member
 
Join Date: Nov 2009
Posts: 10
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
 
Electrical draw of autopilots?

I am looking for a selfsteer solution for a 26' sailboat. I am leaning towards an autopilot instead of a windvane, but am concerned about running out of juice powering it.

The Simrad TP20 which I am looking at states that it draws 500mah, but in past experience, you cannot accurately calculate exactly how long a battery will last based on just that.

I am thinking I will have to install 4-6 deep cycle marine batteries, and a small generator. But even then, will I have to run the generator every day?

What's your experience? Thanks!
peteris is offline  
Quote Quick Reply Share with Facebook
Sponsored Links
Advertisement
 
post #2 of 24 Old 11-10-2009
Senior Member
 
Zanshin's Avatar
 
Join Date: Aug 2006
Location: Germany
Posts: 2,297
Thanks: 0
Thanked 29 Times in 27 Posts
Rep Power: 9
 
The real drain is when the autopilot needs to do work. If the boat is not balanced, the autpilot set to maximum sensitivity and the seas uneven you will drain more power. the 500mAh is just the minimum drain when turned on, but that is only 12Ah for a 24 hour period and a typical boat battery will have 100Ah. Does your boat have any means of charging batteries (perhaps an alternator on the outboard/inboard)? When the Simrad has to control the boat the drain will go up to several amps while the motor is turning.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Zanshin is offline  
Quote Quick Reply Share with Facebook
post #3 of 24 Old 11-10-2009
Senior Member
 
nickmerc's Avatar
 
Join Date: Nov 2008
Location: O'Fallon, MO
Posts: 563
Thanks: 0
Thanked 1 Time in 1 Post
Rep Power: 7
 
I have an old Autohelm 1000 for my Pearson 30. I can sail about 10 hours (80% under autohelm) anchor overnight with my 12 VDC cold plate running, cabin lights and anchor light all night (incadecent bulbs) and make the return trip the next day and have plenty of juice left over. I have 2 group 24 wet cell batteries for my house bank. The only time my engine runs is leaving the dock, dropping and hauling the anchor, and returning to dock. In total about 45 minutes for the trip. I do start off with a full charge.
________
Live sex

Last edited by nickmerc; 08-18-2011 at 05:33 AM.
nickmerc is offline  
Quote Quick Reply Share with Facebook
post #4 of 24 Old 11-10-2009
Telstar 28
 
sailingdog's Avatar
 
Join Date: Mar 2006
Location: New England
Posts: 43,290
Thanks: 0
Thanked 15 Times in 12 Posts
Rep Power: 14
         
As Zanshin has pointed out, the draw of the typical autopilot will vary with the balance of the sailplan. To minimize the draw, try and balance the sailplan as much as possible when using the autopilot.

As to whether you'll need to run the generator every day, it really depends on how large your battery bank is, what your typical daily electrical usage is, and what passive charging systems you have aboard. On my boat, I can run my refrigerator, the VHF, autopilot and such and still have the three solar panels keep the batteries fairly well topped off... never have to run the engine to charge the batteries, which is a good thing, given the low amperage output it has.

Sailingdog

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Telstar 28
New England

You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
a boat to the sea you don't love, she'll shake you off just as sure as the turning of the worlds. Love keeps
her going when she oughta fall down, tells you she's hurting 'fore she keens. Makes her a home.

—Cpt. Mal Reynolds, Serenity (edited)

If you're new to the Sailnet Forums... please read this
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
.

Still—DON'T READ THAT POST AGAIN.
sailingdog is offline  
Quote Quick Reply Share with Facebook
post #5 of 24 Old 11-10-2009
Senior Member
 
mitiempo's Avatar
 
Join Date: Sep 2008
Location: Victoria B.C. Canada
Posts: 7,502
Thanks: 0
Thanked 96 Times in 87 Posts
Rep Power: 8
   
I'd do anything I could to avoid running the generator - solar first choice as it's the least annoying with no moving parts. Windvane is a good choice and most wouldn't use the autopilot unless under power. Are you going offshore or daysailing?
Brian
mitiempo is offline  
Quote Quick Reply Share with Facebook
post #6 of 24 Old 11-10-2009 Thread Starter
Junior Member
 
Join Date: Nov 2009
Posts: 10
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
 
Going offshore, looking to do Panama -> French Polynesia -> Australia. I know a windvane is probably what I should be looking at, but I'm wondering if some of you rely only on autopilots even for offshore.

I'm the barebones type and would be running strictly the autopilot on batteries. No radar, stero, fridge, etc... I don't mind burning a little bit of petrol for a few hours here and there, just don't feel like running my engine or the generator 24/7. I've heard solar panels only really produce about 20% of their rated output, and that just doesn't cut it.
peteris is offline  
Quote Quick Reply Share with Facebook
post #7 of 24 Old 11-10-2009
Senior Member
 
mitiempo's Avatar
 
Join Date: Sep 2008
Location: Victoria B.C. Canada
Posts: 7,502
Thanks: 0
Thanked 96 Times in 87 Posts
Rep Power: 8
   
The better solar panels will do better than that, of course only when the sun is shining. See this link for good solar advice.Solar Power on Boats | Adrift at Sea
As sailingdog says, he really never has to run the engine to charge his batteries - solar takes care of it. And I bet he runs more electrical items than you will. You should be able to get all your amps from a solar panel of a reasonable size taking into account your planned electrical items.
For the distance you're going to travel I'd certainly take a good wind vane which will take care of 98% of your steering as you're not going to power long with the fuel you could carry on a 26' boat. I'd probably throw the generator overboard out of annoyance. Besides you can't easily fill the fuel tank in rough weather, when you need the self steering the most. As well the tillerpilot will not use the miniscule power the specs say when it has to work hard.
Here's a link to what I think is a good fairly affordable wind vane.NORVANE Self-Steering Wind Vane. Stainless steel, servo-pendulum. Powerful, sturdy and reliable for sailboats 20’ to 60’
If you already have the tillerpilot I think it will be of some use when powering in calmer conditions but I don't think it's up to steering offshore in all conditions as a good vane is.
Brian
mitiempo is offline  
Quote Quick Reply Share with Facebook
post #8 of 24 Old 11-10-2009
Telstar 28
 
sailingdog's Avatar
 
Join Date: Mar 2006
Location: New England
Posts: 43,290
Thanks: 0
Thanked 15 Times in 12 Posts
Rep Power: 14
         
LOL... Mitiempo, did you know that is my blog???

Peteris—

I'd second getting a windvane instead of an autopilot. The main reason for this is that a windvane will work in heavier conditions than an autopilot, and not use any amp-hours. In heavier winds, the tiller pilot will use a lot more amps than the minimum and there's much more chance of it failing than a windvane, since the windvane works with more force as the wind strength increases, which is not the case with an autopilot. Also, minimizing electrical usage on longer voyages is a necessity, especially if you're going to be relying on a generator for charging—since fuel is a scarce resource on the open ocean.

Sailingdog

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Telstar 28
New England

You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
a boat to the sea you don't love, she'll shake you off just as sure as the turning of the worlds. Love keeps
her going when she oughta fall down, tells you she's hurting 'fore she keens. Makes her a home.

—Cpt. Mal Reynolds, Serenity (edited)

If you're new to the Sailnet Forums... please read this
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
.

Still—DON'T READ THAT POST AGAIN.
sailingdog is offline  
Quote Quick Reply Share with Facebook
post #9 of 24 Old 11-10-2009
Member
 
Join Date: Oct 2009
Location: Maine Coast
Posts: 64
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 6
 
Some wind vanes also function as emergency rudders, which hopefully you'll never have to use....
marujosortudo is offline  
Quote Quick Reply Share with Facebook
post #10 of 24 Old 11-10-2009
Senior Member
 
mitiempo's Avatar
 
Join Date: Sep 2008
Location: Victoria B.C. Canada
Posts: 7,502
Thanks: 0
Thanked 96 Times in 87 Posts
Rep Power: 8
   
Yes dog, I knew it was your blog - full of good info.
To expand on your post though, sailors in Ostar and other singlehanded races with smaller boats with tillerpilots usually take several to allow for breakages. And I just can't see filling a tank and running a generator on a 26' boat not when you want to but when you have to charge the batteries - rough or calm.
Brian
mitiempo is offline  
Quote Quick Reply Share with Facebook
Reply

Quick Reply
Message:
Options

By choosing to post the reply above you agree to the rules you agreed to when joining Sailnet.
Click Here to view those rules.

Register Now



In order to be able to post messages on the SailNet Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
Please note: After entering 3 characters a list of Usernames already in use will appear and the list will disappear once a valid Username is entered.


User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Similar Threads
Thread Thread Starter Forum Replies Last Post
Calculating Your Electrical Load Kevin Jeffrey Gear and Maintenance Articles 0 03-03-2003 07:00 PM
Electrical Power on Board Kevin Jeffrey Gear and Maintenance Articles 0 02-11-2003 07:00 PM
Electrical Power on Board Kevin Jeffrey Her Sailnet Articles 0 02-11-2003 07:00 PM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome