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Author Topic:   Loran Interference from E-TEC
Dennis B posted 04-22-2007 06:38 PM ET (US)   Profile for Dennis B   Send Email to Dennis B  
I have a 1989 Boston Whaler Montauk and I just re-powered with a new Evinrude E-Tec 90. My old motor was a V-4 Johnson 90. This conversion entailed a new throttle assembly, new tach, new oil gauge, new water pressure gauge and power tilt trim gauge.

I have been using an Impulse 2831 LORAN and SONAR combo. After installation of the new motor, the fishfinder works fine, but the LORAN indicates "looking for signal" (no bars)when the motor is running. The LORAN works when the motor is off. I replaced the antenna and the coupler, and have tested with two other Impulses and the same thing happens.

I live in the SF Bay area and do lots of ocean fishing. I am wondering if anyone else has encountered this problem or has any ideas as to what the solution would be. Any input would be appreciated.

Thanks, Dennis

Chuck Tribolet posted 04-22-2007 07:35 PM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
Get a GPS, enable WAAS, and transfer your waypoints. You
may need some on-site checking (with motor off) as LORAN-C
is very repeatable, but not terribly accurate.


swist posted 04-23-2007 07:09 AM ET (US)     Profile for swist  Send Email to swist     
I'm sure it's some sort of RFI that the engine was never tested for. LORAN operates on weird frequencies (real low). But it's pretty much obsolete. Get a GPS, you'll never miss the LORAN.
contender posted 04-23-2007 11:14 AM ET (US)     Profile for contender  Send Email to contender     
Try running a direct power line and ground line to the battery and have a fuse in-line with a switch. Did you do anything with the current LORAN cable? There use to be two types of cables for the antenna make sure you have the good one. Other than this I can not think of anything else, LORAN was pretty straight forward positive, negative, and antenna. I know that Impulses came from Calfornia address: Impulse Technology 695 Railroad Ave. Pittsburg CA. 94565 Phone 415 439 2072 Fax 415 427 1920 Customer service 415 427 2567/95. Do not know if still in business. I do know they were adhead of there time, heard they were bought out for there technology, it is a shame they were great company with top of the line items.
jimh posted 04-23-2007 08:29 PM ET (US)     Profile for jimh  Send Email to jimh     
LORAN-C operates on one frequency, 0.1-MHz. It is not particularly "weird."
HAPPYJIM posted 04-23-2007 08:32 PM ET (US)     Profile for HAPPYJIM  Send Email to HAPPYJIM     
It might be worth checking the output voltage of the motor. Make sure the battery is connected and terminals tight.
roloaddict posted 04-24-2007 12:03 AM ET (US)     Profile for roloaddict  Send Email to roloaddict     
Your new motor may be noisy on the LORAN freqs. Whether it is the ignition, the charging system, the computer, the Smart gauge system all would be likey culprits.
Without the large square footage of conductive ground plane (metallic hull or Newmar ground shoe)needed to "pull" that signal above the noise level of your new motor you maybe fighting a losing battle by spending money on an outdated system.
Buy a GPS.
As a side benefit, your new GPS would give you accurate Speed Over Ground (SOG), so you can properly evaluate your propeller choices.
If your motor is noisy at LORAN freqs, then a DGPS may not give you the best performance, so the previous recommendation concerning WAAS corrections may prove valuable.
Dennis B posted 04-24-2007 12:47 AM ET (US)     Profile for Dennis B  Send Email to Dennis B     
Thanks, guys, for your replies and suggestions. To Contender: I was going to do what you recommended and run a direct power line to the battery. When I removed the battery cover, I noticed that there were only two connections to the negative post, when normally there were three. I picked the battery box up and, lo and behold, the ground cable was underneath the battery box. My mechanic had bundled all of the cables in a very neat wrap, and the ground cable was positioned so that it wouldn't reach the post for me to connect it. So I'm bringing the boat back to the mechanic to fix it. I hope this will solve the problem with the loran. In the meantime I purchased a GPS, so if the LORAN fails, I will have a backup nav system. I really love the Impulse 2831. Bought one new in 1989 when I bought my boat, bought a (new) backup in 1996 from Mike's Marine in Pittsburg CA, bought another one (new) for $125, so it's apparent I really like the unit! I fish out of San Francisco and run out The Gate about 20 times a year, also fish out of Half Moon Bay probably 20 times a year, and the Impulse has been perfectly reliable in pea soup fog conditions. It's always brought me home!
I'll inform you guys if this solves the problem. I appreciate all the information you've provided.
Dennis B.
jimh posted 04-24-2007 12:50 AM ET (US)     Profile for jimh  Send Email to jimh     
I would think that the radio spectra of emissions from an E-TEC motor would be much lower in level than from a conventional outboard motor of yesteryear. The E-TEC has many electronics devices which might be sensitive to radio-frequency interference, so one would expect that it would not be generating a lot of radio-frequency energy itself. It could easily interfere with itself.

The most obvious question: how close is the outboard to the LORAN antenna? And is the antenna in the same location as before?

jimh posted 04-24-2007 01:50 AM ET (US)     Profile for jimh  Send Email to jimh     
With disconnected battery negative conductors, I think you've found your problem.

Re the E-TEC, Bombardier says:

"...ultra-low RFI levels eliminate interference with your onboard electronics."

contender posted 04-24-2007 08:14 AM ET (US)     Profile for contender  Send Email to contender     
Dennis, I think you found your problem let me know, also did you find out if the company is still in business?...good luck
Dennis B posted 04-27-2007 05:02 PM ET (US)     Profile for Dennis B  Send Email to Dennis B     
Contender: Well, the not-connected ground cable was not the problem. It was actually the ground cable for my second battery. So I'm back to square one. I called Evinrude Technical Parts and they told me to have my mechanic contact them for a fix. They admitted that the E-TEC motors put out a lot more interference. My mechanic if off for a couple of days and will call them on Tuesday.

I have been unable to contact Mike's Marine Repair, as it seems that they are no longer in business. I talked to his wife last November, and she said that parts are scarce for Impulse. Last night, I called the number I have for him and a person answered and said they have his old number and they don't know what happened to him.

While surfing the internet, I found a company called Jaytron Service in Bradenton, FL, and called this morning to explain my situation. I spoke with the owner. He seemed very knowledgeable and said that this could really be a complicated problem to diagnose and solve. Unfortunately, I can't bring my boat to Florida from SF for him to check it. If you would like to contact him for any problems you may have, his phone number is 941-748-1941 (M-F 8am-5pm).

I'll let you guys know how I make out.

Dennis B

seahorse posted 04-28-2007 12:19 AM ET (US)     Profile for seahorse  Send Email to seahorse     
It's been many many years since I've been involved with LORAN installations, but back in the Sitex and King LORAN days there were a lot of interference problems.

You have to run separate power and ground leads directly from the battery and route them so they are not close by or bundled with the boat and motor wires. In severe cases we would have to twist the wires around each other, or run them from a different battery.

Also there is usually a wing nut and stud or a ground post on the back of the unit (not the 12V ground) to run a copper strap or #10 wire down to a thru-hull grounding plate, a granular copper disc or rectangle that is in contact with sea water while the boat is running.

Make sure the antenna and wiring are away from the motor and not near any of the boat wiring.

jimh posted 04-28-2007 10:54 AM ET (US)     Profile for jimh  Send Email to jimh     
Based on what's been presented, it seems reasonably clear that the E-TEC motor is the source of whatever noise or interference is affecting the LORAN receiver. The next step is to determine the way the interference is conducted into the LORAN receiver. There are two paths: common-mode power line noise or radio wave propagation.

The noise or interference may be getting into the LORAN receiver via the power lines. This can occur if there are any segments of the power distribution which are in common between the two devices. To reduce the common-mode noise, connect the LORAN directly to the power source with independent wiring. Run the LORAN power conductors right to the terminals of the battery. To test if the power common-mode distribution is causing the problem, you can operate one of the devices from a separate and isolated power source. In this case, run the LORAN receiver from a separate battery. If this eliminates the interference, then it is likely the interference was being conducted on the power lines.

The LORAN receiver is listening for radio signals, and, if the E-TEC motor is emitting radio frequency noise in the same spectra or band as the LORAN is trying to receive, the interference will be conducted to the LORAN via radio wave propagation. To reduce this sort of interference there are only a few remedies.

Radio wave propagation obeys the usual square-law rules, so the farther the LORAN and its antenna are located from the engine, the weaker the interference will be. Usually the motor position cannot be move, so you have to move the LORAN antenna to be farther from the motor.

If the E-TEC motor is producing strong radio signals which are on the same frequency as the LORAN, there is little that can be done. This is called in-band interference. It is unlikely that you can make effective modifications to the E-TEC to suppress the generation of these signals or to shield them from the LORAN. About the only suggestion I can offer is to apply some foil shield to the inside of the cowling. This may help suppress the interference.

If the E-TEC motor is producing strong radio signals which are NOT on the same frequency as the LORAN, you can try to prevent these signals from affecting the LORAN by filtering them out. This is called out-of-band interference, and it can be effectively reduced by use of filters in the transmission line between the antenna and the LORAN receiver.

The antenna installation is also an important factor. If the antenna is designed so that in order to work it needs an effective ground connector or a counterpoise connection to the sea, you may be inducing the interference into the antenna system by relying on the motor to act as part of the antenna system itself, that is, the part that provides the counterpoise. If the motor itself is part of the antenna system, it could also be directly inducing noise into the receiver as opposed to noise conducted by radio wave propagation.

I would not spend too much time or money on seeking a solution to this inasmuch as you can replace the position finding information from the LORAN with a new GPS for about $50. I can't think of much that you could do to make the old LORAN work better that wouldn't cost more than $50.

In the heyday of LORAN it was quite common that specialized filters be placed into the power wiring for the LORAN, and often this included specialized filters which were placed in the negative lead. The LORAN manufacturer may be able to offer advice.

Inside of a modern outboard motor there are many potential sources for radio frequency interference. However, since the motor itself is very sensitive to such interference, the primary source, the engine ignition sparking, is generally handled in a very careful manner. It is typical to find that the ignition spark wiring is carefully shielded with grounded flexible shields to suppress radio-frequency interference, whereas in older outboard motors this was seldom done. This practice is necessary to prevent the engine from interfering with itself, and, as a result, tends to make the modern engine have less radio-frequency interference than older engines.

You might also consider now long into the future the LORAN system will be functioning. The most current information I could find said:

"The Department of Transportation in coordination with the Department of Homeland Security is considering the need to continue to operate or invest in the North American LORAN–C Radionavigation System beyond fiscal year 2007."


jenkinsph posted 04-29-2007 12:10 AM ET (US)     Profile for jenkinsph  Send Email to jenkinsph     
Jimh's description of the problems are "right on" if the interference is in the same band it is too much to contend with. Plus if the system is shut down your back to square one.

Chuck is "right on" with the right cure, get new GPS and do
the transfers and waypoints. You will be time and money ahead.


Dennis B posted 04-29-2007 01:15 AM ET (US)     Profile for Dennis B  Send Email to Dennis B     
jimh: I bought a new hand-held Garmin GPSMAP 76CSx yesterday. I can't tell you how disappointed I am in the unit. I installed 80 waypoints (which took me 2 hrs). I put them in as routes (I fish out of Monterey, Moss Landing, Santa Cruz, Half Moon Bay, and San Francisco Bay along the Coast, sometimes going out 40-50 miles for albacore.) I normally use 10 waypoints for each harbor and I put them in the GPS in the order I use on my Impulse loran, logically for each harbor. On the GPS they came out randomly, not in route order. The GPS compass does not show compass headings. It has an arrow the user is supposed to follow, which is very difficult while running the Montauk at the speed I travel on-plane.

I'm determined to fix the problem between the E-Tec and Impulse loran. Again, I have 3 units, which all worked with my old 1989 Johnson 90hp V-4. I hope my mechanic can work this out with Evinrude's tech support. I'll find out by Wednesday.

Dennis B

jenkinsph posted 04-29-2007 04:42 AM ET (US)     Profile for jenkinsph  Send Email to jenkinsph     
Dennis, after looking up the unit and looking at the specs I think you need to spend more time to understand all the functions and capabilities. Give it a chance!!! You have it for one day and are frustrated with it. I learn something new every trip and have had my unit for 2 years.
GPS mapping is great thats why most of us use it.

Conceptually this is very different from loran, with a
gps unit the larger screen is your moving chart. A large screen is easier to see on plane. My Lowrance has a compass heading screen thats easy to use, but I don't need it much. Not when I can drive realtime right up the chart in front of me with depth contours ect. In the reservoirs that I fish in being off course can be hazardous. How about a cliff or boulder just below the surface. You, on the otherhand appear to be heading out to sea and want to follow a compass heading or multiple headings and be able to see these to steer, you can still do this. A lot more can be done with saved trails to your favorite hotspots ect.

If you know where to find the fish and have this knowledge and experience your way ahead of most of us. The transition to using the gps format is easy. Just remember that gps is more visual oriented so that a large screen say 7 inch and up is more practical.

I am very grateful we don't have 50 lb vhf's, 200 lb radars
with bulky crt displays, and MS DOS without Windows. The new electronics are better and cheaper in every way.


JayR posted 04-29-2007 08:51 AM ET (US)     Profile for JayR  Send Email to JayR     
The future of Loran is in question. It may be decomissioned.... Might want to spend a bit more time getting familiar with that GPS unit

jimh posted 04-29-2007 01:37 PM ET (US)     Profile for jimh  Send Email to jimh     
I have no idea what GPS unit does what or how well it does it. This is why I have never made a recommendation or offered any advice about what particular unit one ought to buy.
Chuck Tribolet posted 04-29-2007 06:02 PM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
Dennis: if you put the routes in right, they will be in order.
I've found it a lot easier to do routes on the computer and
then download them with Garmin MapSource, than to do them on
the GPS itself, but it's still quite doable on the GPS.

I have no problem following the arrow on plane, and faster.
Just keep the arrow pointing ahead, and you get there.


contender posted 04-29-2007 10:52 PM ET (US)     Profile for contender  Send Email to contender     
Dennis, just got back it town today, do as seahorse stated try running the loran its own wires, and stay away from the other wires, sorry for your problem but I think everyone is correct loran will soon be dead, get a good gps and learn it well, now back to my sextant and slide rule, thanks for the phone number...good luck
Dennis B posted 05-01-2007 07:51 PM ET (US)     Profile for Dennis B  Send Email to Dennis B     
My mechanic has contacted Evinrude about this E-Tec/loran problem and they said they have had many complaints regarding E-Tec/loran compatibility due to the RFI. They said that the fix will be a problem, but I should follow most of the advice from all you who have replied...get a GPS or run the loran off a separate battery as far away from the engine as possible. I have a friend who is an expert in electronics and he is going to attempt to solve this. I will let you guys know how I make out.

I really appreciate all the suggestions. I agree that I should give the GPS more of a chance and try to learn it better.

I read in Boat US that the loran system was going to be extended to at least 2011. So, I'm like a bulldog (and OLD one!) and WILL TRY TO FIX THIS!!! I figure I'll be TOO OLD to run my Montauk by the time Loran is discontinued!

Thanks again you guys!


seahorse posted 05-01-2007 09:40 PM ET (US)     Profile for seahorse  Send Email to seahorse     

Try all the suggestions, and if they don't work, install Champion QC10WEP plugs gapped to .028" and index correctly, and see if that helps. It's not a factory fix, EPA approved, or even tried before for LORAN interference, but the different style plugs are known for less RFI.

Dennis B posted 05-09-2007 06:47 PM ET (US)     Profile for Dennis B  Send Email to Dennis B     
Here's an update on the Loran/E-Tec RFI problem: I isolated the Impulse power cable to the secondary battery and it only halfway solved the problem. Only two of the four stations locked in while the motor was on. So I have studied my new Garmin GPS some more and feel more confident in it.

I called Johnson & Hicks, a marine electronics company in Santa Cruz, and inquired about fixed mount GPS/fishfinder combos. They gave me a few recommendations and I will look into them. I mentioned my problem to the rep and he said it COULD be fixed by installing a "noise separator". I was thinking about buying the separator and taking the chance it will work. So I went to an electrical supply store and asked about noise separators, after explaining my problem. He said he didn't think it would work, because the interference is probably not coming through the cable, but through the air. He said to try putting a metal garbage can over my motor to test that theory. Or to paint the inside of the cowling with metal paint. I don't think I'm going to try either of these! Of course, someone else has mentioned lining the cowling with aluminum foil.

I think I'll stick to the GPS for now! I've been talked into it! It's not so bad, after all!

Stubborn Old Dennis

P.S. Anyone want to buy a perfectly good Impulse Loran/Fishfinder? I have three in stock!

contender posted 05-12-2007 03:57 PM ET (US)     Profile for contender  Send Email to contender     
Are they new in the box? which model numbers?
jimh posted 05-13-2007 12:32 PM ET (US)     Profile for jimh  Send Email to jimh     
I have never heard of a "noise separator." Can you describe the electrical principles of its operation?
contender posted 05-13-2007 11:16 PM ET (US)     Profile for contender  Send Email to contender     
Jimh, I have one on my contender, it has been on a long time (since 91), I will look at it tomorrow and give you what info I can. All I remember it was some thing for the electronics, some type of noise/static remover.
Dennis B posted 05-16-2007 11:36 PM ET (US)     Profile for Dennis B  Send Email to Dennis B     
To Contender: 2 of the units are Model 2831 and 1 is a 2830. The only difference is the housing. The 2831 is more water-resistant. No, they're not new in the box. I purchased my first unit (2830) in 1989 when I bought my Whaler. I had Mike's Marine update it every 4-5 years. The second unit (2831) I bought from Mike around 2000. The third unit (2831) I bought on eBay 2 years ago. All of them are fully functional. But now, with my E-Tec interference problem, I'll just use them for the fishfinder. You were right on when you said that they were way ahead of their time. I've had friends fish with me on numerous occasions with their GPSs and my Loran unit has been more accurate on every occasion.

I have been checking on eBay recently and have seen 3 units sell for around $75-$100, unit coupler, no antenna, no transducer. Without the coupler ($185), the Loran unit is useless.

To JimH: No, I can't explain the electronics of a "noise separator". I went to an electrical supply store in my area to look for one, but they were out of stock. I was told by the rep at Johnson & Hicks in Santa Cruz that they were about $65 each. I assume it is similar to a noise filter on a phone or computer line.

Dennis B

contender posted 05-17-2007 09:18 PM ET (US)     Profile for contender  Send Email to contender     
Dennis best to keep them for parts, The weakest part of the units was the loran board, all of your units are interchangeable hange on to them...good luck
lostone posted 03-19-2008 02:46 AM ET (US)     Profile for lostone  Send Email to lostone     
[Seeks] the antenna for this unit. Thanks

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