Hi Phil,
It occurs to me that all electrical/electronic equipment sold for marine use needs to have its "Compass Safe Distance" quoted - particularly so for loudspeakers but most (all?) makers withhold this information because it is often frightening. How about your kickers?
CSD is the distance at which a 1° compass error is introduced. This is normally used for main steering compasses and several such perturbations together can still amount to sizeable errors.
CSD quoted? Not for most manufacturers. Why? Lawyers in all likelihood. Just a guess...
As a product manager, here is my take: CSD is a complex issue, as flux density from the "offending object" varies depending on the angle at which you meaure it. Pretend you have a sphere about a speaker or other potentially offending object and measure points about the sphere; you will find that the measurements are not uniform in strength. Compounding the issue is that entertainment, (as opposed to communication) speakers are usually used in pairs, and their flux can be additive, or cancelling, depending on mounting distance, angle, and location.
As your comment suggests, multiple offending objects compound the issue, such that in certain installations while every item is outside of a CSD distance, the compass error can be sizeable. I am not taking a CYA position per se, but will tell you there are too many variables, such that making any statement about any product with regards to CSD has the potential to set the consumer up for disaster; it provides a false security... The onus of responsibility lies with the installer, either at the plant, the yard, or with the consumer to verify that the addition of any materials, (be they simply ferrous materials, magnetic materials, or any other item having the potential to affect the compass) be accounted for in checking for compass deviation to make sure the final mounting location of all parts including the compass is suitable, and the compass corrected if necessary.
Consider this potentially litigious situation: There might be an instance on an existing boat where the addition of a CSD-spec'd item might (considering the adjacency of other prior installed "offending objects") induce a greater than 1-degree error as a result of the summed effect of all "offending objects", resulting in a navigation failure and damage to property or life. The fault for the navigation error
should be able to be proved to be the summing effect of all "offending objects". However, the CSD statement made by the manufacturer of the last "offending object" added, might result in a suit agains the manufacturer of the last added object; the manufacturer could be blamed for the error based on his CSD statement. The fact is, the
installation fo the object is to be pointed to as a causal effect, but due to a "safe distance" statement, the manufacturer of the last item added might end up paying damages, despite truly being faultless.
As an artificial hip recipient, I can tell you I am concerned enough about my legs causing deviation that I want to check it...
I share that somewhat tongue-in-cheek, as I sincerely hope there is no ferrous material in my prosthetics. Still, one should realize that any steel or ferrous material brought on board will affect the compass to some degree, magnetized or not.
To succinctly address your query, I will suggest to you that the shielded Kicker loudspeakers will affect a compass to a lesser degree than most other loudspeakers based on the level of shielding we designed in. That being said, our speakers are designed to
minimize compass deviation. We do not share that they will eliminate it because that is not truthful, nor is it prudent. I would be lying if I told you otherwise...
As an ABYC/NMMA member who is an engineer first and a salesman second, (who also happens to be an avid boater, both sail, power, and vintage wood), I will tell you that the prudent thing to do is to mock up your installation of all items and then test prior to final placement. In Dean's post, and for his benefit, I would share that the shielded Kicker speakers probably will affect his compass the least when compared with the others, but if the mounting distance is too close and the angle is just right, the installation might compromise autopilot function regardless of speaker installed, regardless of brand, shielded or otherwise....
Sorry for the long post, but hopefully that is now completely clear as mud....
Phil
