Installing Raymarine AIS700 and RF Ground

[Tenedos]

I just installed a Raymarine AIS700 and it works nicely. However it does have an explicit Ground, and the following strong warning in the manual:

Grounding
The AIS700 includes a dedicated grounding poin to reduce potential damage caused by near lightning strikes.

The Grounding point must be connected to your vessel’s RF ground; this is NOT an optional connection. Do NOT connect to any point that is connected to your vessel’s 0V Negative battery terminal.

So, I don't think I have RF Ground on my boat and it clearly says don't connect to Negative battery terminal.

So what I do I?

[freebird22]

Same question here, although a recent YouTube Video apparently gets away without it.

https://www.youtube.com/watch?v=GnUW_vSqJJE

[Pete7]

Originally Posted by Tenedos

I just installed a Raymarine AIS700 and it works nicely. However it does have an explicit Ground, and the following strong warning in the manual:

So, I don't think I have RF Ground on my boat and it clearly says don't connect to Negative battery terminal. So what I do I?

The good news is you have a European yacht and a Jeanneau at that

You have a bolt on keel, so you could connect it to one of the bolt backing plates.

Pete

[Smunkey]

I ran into this issue as well. Their current install manual changed this verbiage effectively removing the word "NOT" from the sentence regarding "0V Negative".

So, being confused by the conflicting information, I reached out to Raymarine and got a helpful and informative answer. Hopefully this helps future installers:


Good question. The latter recommendation, to connect to battery negative, is the current one that should be followed.

The ground point on the AIS is there to protect the AIS against static build-up in the antenna or electrostatic discharges from nearby (not direct) lightning strikes. The idea is to give a preferential path to drain away transient high voltages.

Originally we said that the AIS's ground point should only go to a dedicated sea earth (an RF or lightning-protection ground.) This is the ideal, however few boats that fit AIS have a dedicated lightning-protection or RF ground, and what we found was that most installers were simply leaving the ground connection unconnected and this was leading to damage in the AIS hardware in not-infrequent cases.

We have therefore changed the instructions to say that you should connect to battery negative, with the thinking that the battery will provide quite sufficient a current 'sink' to effectively absorb most ESD transients. If the transient is large enough that the battery can't absorb it and you end up with a reverse voltage sufficient that it could put other products connected to battery negative at risk, then the transient is likely high enough that it would cause significant damage however the ground was connected or not connected, e.g. a direct lightning strike.

Short answer: much better to connect the ground to battery negative than not at all, which is what most people were doing under the old instructions.

[Tenedos]

This is a very useful information. Thank you for following up.