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Author Topic:   Sealing Electrical Terminal Connections
jimh posted 09-22-2009 09:06 AM ET (US)   Profile for jimh   Send Email to jimh  
On a drawing from Boston Whaler describing details of the installation of electrical components, I noted the following instruction:


I am confident that the T-9 spray refers to Boeshield T-9®, a protectant and lubricant developed by the Boeing Corporation. Their literature notes:

"Boeshield T-9® is a solvent and paraffin wax based formula with over a dozen components including corrosion inhibitors.... Because of its high dielectric it may be applied to electrical circuits, controls, and wiring."

In inspecting many new Boston Whaler boats, I have noticed that exposed electrical terminals and connectors were coated with some sort of sprayed on film. That appears to be Boeshield T-9.

Using Boesheild T-9 to protect exposed electrical terminals may be a good practice to follow in any small boat electrical system.

ConB posted 09-22-2009 01:11 PM ET (US)     Profile for ConB  Send Email to ConB     
Boeshield T-9 is really good stuff. I've used it on boats and fire arms for years.

Being a fresh water boater I never thought to stray it on electrical connections.


fishgutz posted 09-22-2009 02:10 PM ET (US)     Profile for fishgutz  Send Email to fishgutz     
Wow, after checking Boeshield's website and its application for bicycles I realized I've been using a similar product called LPS 3 for years on mountain bikes. LPS 3 is easily found at most hardware stores.
bluewaterpirate posted 09-22-2009 02:17 PM ET (US)     Profile for bluewaterpirate  Send Email to bluewaterpirate     
Whaler has been using Boeshield for a number of years. I just finished installing marine electronics on a new 280 Outrage ... they even use it behind the the helm areas. Image-4892322-61696683-2-Web_0_9b1d8ad797a8e159bb314b8235155a01_1

terminalscheap posted 08-13-2010 10:00 AM ET (US)     Profile for terminalscheap  Send Email to terminalscheap     
Boeshield T-9 is really good stuff. Is the more preferable.
jimh posted 08-13-2010 12:09 PM ET (US)     Profile for jimh  Send Email to jimh     
Thanks for reviving this discussion to add your concurrence.
dino54904 posted 08-13-2010 01:09 PM ET (US)     Profile for dino54904  Send Email to dino54904     

If you use the heat shrink terminals do you also need to use T-9? Is there a benefit?

jimh posted 08-13-2010 02:25 PM ET (US)     Profile for jimh  Send Email to jimh     
T-9 is sprayed direction onto the electrical connections after all the terminals have been tightened and connections made. If protects the exposed metal of the terminal post, not the wire-to-terminal-connector.
contender posted 08-13-2010 03:21 PM ET (US)     Profile for contender  Send Email to contender     
If you use heat shrink you should still use the T-9 or LPS3. Another way to go is using the plastic coat. Dip the terminal end in the stuff and just clean off the end for the connection. And then like Jim said after all the connections are made spray the terminal end connections...good luck
dino54904 posted 08-13-2010 04:58 PM ET (US)     Profile for dino54904  Send Email to dino54904     
Thanks for the clarification and information. Now it's off to the store for a can of T-9!
glen e posted 08-13-2010 08:36 PM ET (US)     Profile for glen e  Send Email to glen e     
T-9 is great for connections and terminal blocks but don't expand it to being an all over spray - for things such as your powerhead which many people do. Use something thinner and more often for that like CRC 656. T-9 leaves a thick waxen coating which makes engine dismantling a mess. Techs hate it.
jimh posted 08-14-2010 08:13 AM ET (US)     Profile for jimh  Send Email to jimh     
I have never used LPS-3, but if used, be sure you get the "-3" version and not the more common LPS-1 or LPS-2. They're lubricants, and not much for protecting electrical circuitry.
seahorse posted 08-14-2010 08:31 AM ET (US)     Profile for seahorse  Send Email to seahorse     

Another commonly used spray protectant that leaves a waxy film is CRC Heavy Duty Corrosion Inhibitor that has a good reputation and a long history in the marine industry.

I have seen it protect battery postive posts and cable terminals that were exposed to saltwater spray.

dfloeter posted 03-31-2011 08:24 PM ET (US)     Profile for dfloeter  Send Email to dfloeter     
Resurrecting an old discussion: I sprayed T-9 on a Command Mic plug and socket at the pedestal mount of our Catalina 30 and have not been able to use it since. I eventually bought an extension cable and ran that straight from the radio in the cabin. I did try mechanical cleaning with various sprays and solvents and nothing has worked completely. The Mic occasionally works but not for long. T-9 works and sometimes too well.

This is just a cautionary tale.

jimh posted 03-31-2011 09:26 PM ET (US)     Profile for jimh  Send Email to jimh     
T-9 works great for its intended purpose. It should never be sprayed onto electronic connectors before they are mated.
towboater posted 04-01-2011 12:43 AM ET (US)     Profile for towboater  Send Email to towboater     
Ive been using various lubricants for years.

I read the Boeshield promo, thanks, sounds like good stuff but I didnt read/see the fine print.

Jim mentions T-9 should never be applied before mating, I take this to mean T-9 is NOT a conductor. Thanks.

Is T-9 messy? Do you recommend brush or spray on after mating?

jimh posted 04-01-2011 07:52 AM ET (US)     Profile for jimh  Send Email to jimh     
T-9 is non-conductive. That is what "dielectric" means. The purpose of applying T-9 and all other dielectric products (such as dielectric grease) is to prevent electrical conduction. Why someone would spray dielectric material directly onto electrical contacts before connecting them to a terminal or receptacle is not known to me. A dielectric material like T-9 is applied after an electrical connection has been made in order to create a non-conducting film around the connection which will keep out moisture and prevent corrosion. T-9 does not restore connections. It is not a solvent or a wash. It is a sealant. If an electrical connection is bad, and you seal it with T-9, it will still be bad.
towboater posted 04-01-2011 11:03 AM ET (US)     Profile for towboater  Send Email to towboater     
Sounds like brush application would be best.
Everything is new.


bluewaterpirate posted 04-01-2011 01:00 PM ET (US)     Profile for bluewaterpirate  Send Email to bluewaterpirate     
Here's some examples of what Jim has described.

2009 280 Outrage BW%20320%20Outrage/2008_0930Whaler5450041.jpg?t=1301680174

2009 250 Outrage BW%20320%20Outrage/2008_0930Whaler5450018.jpg?t=1301680451

Contrast --Here's one I'm going to rewire for one of my clients. It came from the factory this way, a 2010 model very high end boat manufacturer. BW%20320%20Outrage/GW%20255/IMG_1743.jpg?t=1301680558


towboater posted 04-01-2011 01:44 PM ET (US)     Profile for towboater  Send Email to towboater     
I'm heading out to find some T-9 right after I finish this, even though 100% fresh water service.

I've hired a pro electrician, a young guy starting off on his own, former employee of a local Auto-Marine electrical repair shop and new neighbor. I'm supplying everything and helping. I know just enough to get into big trouble. I'm sure his bus layout will look near as good as yours and Jim's, far better than mine would. My problem is, once it works, I'm good to go, no time to waste on looks and long term sealers. hehe.

Job includes 12v, 110 and 220 via 15-kW gen set and shore power. Been waiting a long time to be able to afford this.
Thanks again.

Advise = confidence.


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