Lightning Protection - SailNet Community
LinkBack Thread Tools
post #1 of 1 Old 10-07-2002 Thread Starter
Contributing Authors
Join Date: Jan 2000
Posts: 536
Thanks: 0
Thanked 11 Times in 9 Posts
Rep Power: 18
Lightning Protection

I am considering putting a lightning protection system in my boat. The keel is lead encapsulated in the hull as opposed to a bolted-on keel. What's my best approach for a ground plate? If I bolt a copper strip or bronze plate next to the keel how should I seal the bolt holes?

Sue & Larry respond:
To install a lightning ground on a boat with an encapsulated keel your best option is to affix an external ground. You have an option of using a commercially produced bronze ground plate, like a Newmar Ground Shoe, or fabricating your own by attaching a strip of copper externally to the hull. Both of these recognized and commonly used grounds are attached externally to the hull with machine screws, washers, and locknuts. To seal around the bolt holes, use a quality marine sealant such as 101 by 3-M or Sikaflex 291. 

As lightning likes to travel in a direct path, youíll want to locate your new ground plate as close to the bottom of your mast as is practical. To ensure that you have access to the back of the plate for attaching your fasteners and ground wires, drill your first hole in the hull from the inside out. Make this first hole a small pilot hole, and then drill your full size holes from the outside in. As each hole is drilled, temporarily insert each machine screw to hold the ground in place and ensure the perfect alignment of the holes in your plate with the holes in your boat. 

Our lightning ground on Serengeti, our 46-footer, is a six inch x 18 inch Newmar Ground Shoe. Itís mounted about a foot and a half on the port side of the mast and is held to the outside of the hull by four bronze machine screws.

You might also want to have a look at the series of articles that Kevin Hughes has written for SailNet. He's a master electrician with a lot of experience in grounding and bonding systems on sailboats. Have a look at his most recent article on the topic of lightning protection: Understanding Lightning, Part Two.

Sue & Larry is offline  
Closed Thread

Quick Reply

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


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

Email Address:


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

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

BB code is Off
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