Installing speakers close to the compass or auto pilot

Roughin'it · 02-14-2016, 10:36 PM

The speaker has a magnet in in it. Is there as standard as to how close it can be installed to the compass or autopilot. Appreciate any info I can get.

Thanks

McGillicuddy · 02-14-2016, 11:21 PM

Minimum 3'. Check the effect by turning the speaker on and off and observing any change in the compass/flux gate. If any change noted, move speaker further away.

I was involved in some experiments about 10 years ago where we showed that passing an offshore oil platform or large ship within 50' caused large deviations in flux gate compasses and could cause unintended course changes while on autopilot.

Hawgwash · 02-14-2016, 11:28 PM

The deviation won't likely be the same through 360 degrees either.

boatpoker · 02-15-2016, 06:10 AM

Quote:

Originally Posted by McGillicuddy

Minimum 3'. Check the effect by turning the speaker on and off and observing any change in the compass/flux gate.

On or off, the magnet is still there.

McGillicuddy · 02-15-2016, 02:10 PM

At 3' or more distance, the permanent magnet can usually be compensated for. But the electrical interference from induced current is variable and so has to be tested for.

porman · 02-15-2016, 06:55 PM

Quote:

Originally Posted by McGillicuddy

Minimum 3'. Check the effect by turning the speaker on and off and observing any change in the compass/flux gate. If any change noted, move speaker further away.

I was involved in some experiments about 10 years ago where we showed that passing an offshore oil platform or large ship within 50' caused large deviations in flux gate compasses and could cause unintended course changes while on autopilot.

I found out the hard way that you don't pass underneath a large bridge while on autopilot. Very sudden course change.

psneeld · 02-15-2016, 07:17 PM

I have done it many dozens of times and nary a degree change...all kinds of bridges.

Wonder why bridges do it to some pilots and not others.

mbevins · 02-15-2016, 07:28 PM

Quote:

Originally Posted by psneeld

I have done it many dozens of times and nary a degree change...all kinds of bridges.

Wonder why bridges do it to some pilots and not others.

Just thinking the same thing. Go under a big STEEL bridge all the time. No deviation..

porman · 02-15-2016, 07:31 PM

Quote:

Originally Posted by psneeld

I have done it many dozens of times and nary a degree change...all kinds of bridges.

Wonder why bridges do it to some pilots and not others.

This happened going under one of the floating bridges on Lake Washington in Seattle. The autopilot is an older Raymarine with a fluxgate compass. Sure caught me by surprise. Since then I have gone under several bridges with the autopilot on standby and watched the heading line on the chartplotter go crazy.

markpierce · 02-15-2016, 07:37 PM

On my boat, find the current flows around bridge abutments result in erratic boat course changes as opposed to compass changes. The autopilot adjusts to the direction changes.

**FlyWright** · 02-15-2016, 10:55 PM

I can't even see either of my mag compasses at my lower helm. (Have I said I like redundancy?) I never refer to them with all the electronic info available. I would think the autopilot influences are related to the flux compass location and not the autopilot control or whiskey compass locations.

For my first year or so of operation, I would always disconnect the AP when approaching bridges. Now I leave it connected, but I monitor it closely. I've never had an issue with magnetic disturbances when passing under bridges or very close to commercial and military metal ships.

skipperdude · 02-17-2016, 04:53 PM

I couldn't see installing a speaker anywhere near my helm.
how are you going to hear the engine. If someone wants to listen to music on my boat they have to go out on deck.
I know every rattle whistle,clatter, clunk or tink my boat makes, but I'm a single engine and where I boat there's nobody to tow me home. If the compass or auto pilot are in use that means the boats running.
no time for tunes I'm running my boat.

**FlyWright** · 02-17-2016, 06:17 PM

Quote:

Originally Posted by skipperdude

I couldn't see installing a speaker anywhere near my helm.
how are you going to hear the engine. If someone wants to listen to music on my boat they have to go out on deck.
I know every rattle whistle,clatter, clunk or tink my boat makes, but I'm a single engine and where I boat there's nobody to tow me home. If the compass or auto pilot are in use that means the boats running.
no time for tunes I'm running my boat.

Dave, did I play tunes while we were underway while sturgeon fishing? I often do, but not too loud and I adjust the fader and balance to throw the majority of the sound aft and to port. But when I anchor, I center everything up and enjoy some good music.

My boat's sound system rivals my home's...maybe even a little better. There's a certain spot to stand in the salon on my boat where the balance and resonance is near perfect. If you've never listened to LeAnne Rhimes play her Billy Joel cover of Goodnight, My Angel or Sara Bareilles' Once Upon Another Time in the center of a surround sound system, I highly recommend it. Don't get me started on orchestral masterpieces.

With a lower helm in a boat my size, it's almost unavoidable that one of the speakers be placed near the helm. Fortunately for me, my little Bose corner speakers are of no consequence to compass or autopilot.

Besides, I have twins, a good anchor system, 2 fridges full of food and IPAs and great Vessel Assist coverage!

skipperdude · 02-18-2016, 01:15 AM

I don't recall if you played tunes or not I was having such a fantastic time just being a board your fine craft and enjoying the time on the water I didn't really pay attention.

Sturgeon fishing the way you set up the gear
A unique experience I've never fished that way before and I'll tell you what I've done a lot of fishing. very cool.

But I'm with you sir once the Anchorage hits the water a little Jimmy Buffett will do me fine anytime.

eyschulman · 02-18-2016, 01:27 PM

Where is the flux gate unit?? that is the key. The speakers can be near the control or a remote compass read out unit but not the compass itself. in some boats a remote place away from electrical and magnetic influence is used for actual remote compass location one way to get around the problem.

Heron · 02-18-2016, 02:37 PM

Quote:

Originally Posted by porman

I found out the hard way that you don't pass underneath a large bridge while on autopilot. Very sudden course change.

LOL...Yup. I have a solid steel railroad swing bridge I must go through to get out of my harbor. I learned early on NOT to do that under Autopilot control!

oscar · 02-18-2016, 04:37 PM

Short Captain Oscar's fireside story.......

In Holland in the late 60's we (My Dad, Mom, me and brother) were ready to leave the lake and go on to the "big water".... think Chesapeake. The boat was a Westerly Centaur, twin keel 28' sail boat built to Lloyds Specs, ie a tank.

All winter Dad attended a navigation class. DR, deviation, variation and all that. So, the first time we left the harbor into the great unknown he spent hours preparing a nav plan, and I (a 12 year old) was the autopilot and held the course. We lost sight of land for all of two or three hours and came out on the other side........ Where the hell are we? Turns out we were 5nm off on a 25nm leg.....

This repeated itself several more times on subsequent legs. To say the marital relationship between my parents got strained would be an understatement. I, the helmsman became eligible for being thrown overboard with the anchor around my neck until Bligh steered the next leg himself and got the same result.

Sooooo, here we are, two weeks into a three week family drama, eh, vacation and we're sitting in the cockpit preparing for yet another attempt.

Dad says to Mom, "Hand me the radio." (a Phillips battery powered multi band thing) so he can listen to the weather. Now, in his little workshop Dad had made a beautiful teak, green velvet lined box for the radio, which was mounted right inside the companion way. The Sestrel compass was mounted on the bottom one of three hatch boards.....I'm gonna say within a foot and a half of each other.

As Mom hands out the radio both Dad and I saw the compass do a full 360º

The radio spent the rest of the vacation in the anchor locker wrapped in a towel.

So, keep magnets WELL away from the compass. And, after you're done installing everything, have it compensated, ie "swung" so you know it's reasonably accurate.

Wxx3 · 02-18-2016, 04:59 PM

umm, this does explain a number of weird occurrences.

And, early on, in passing under bridges with tight clearances, I learned to turn off the AP as I felt sometimes, strange "currents" were causing the boat to be squirrelly.

well, probably was a current, just not the one I was thinking about. Probably both in fact.

Thanks for broadening my horizons.

Richard in Vigo, Spain, checking out marinas for next fall.