Reception Problems On The Water With Fm Radio

[Guest TelcoBroker]

I've been trying to get through to Triple J to ask Dr Karl this question but he seems too busy talking to other people about the way an octupus can change colours, people working in pressurised underground tunnels and other boring stuff. Hmmm........... Sour Grapes, he probably wouldn't know the answer anyway.

Stuff Dr Karl, I'm gonna ask Dr Raider.

My question for Dr Raider is:

I have been on numerous trailer boats (all fibreglass) and never been able to get decent reception. It always seems to cut in and out and wander off channel. The reception is fine the second you take the boat off the water. The problem has been evident with both marine and auto stereos. What is the trick to getting good FM reception on the Hawkesbury?

[Kingy]

It's got to do with the modulating frequency of the FM band and the 27MGHz band. It tends to bounce off the water and scatter away from you and is particularly bad on a rough day as the chop deflects the incoming frequencies. Taking the boat out of the water raises your height above sea level and is in a better spot to pick up signals. Also get better rebound response from nearby vertical objects that can increase the strength of a signal. Water is horizontal and much less effective.

This may help, but i'd suggest ringing the real Dr Carl Cruising Schnitzel cause what I wrote above is absolute bullsh#t. sorry for the bum steer

Or maybe try a longer/better aerial. I have 2 six foot aerials and still have trouble picking up FM stations in the Hawkesbury, but on the occasions I've needed to use my 27Mghz, Coastal Patrol picks up my signal down in Botany Bay which is pretty impressive!! I think the high hills around the Hawkesbury don't help the reception. I do know some bands refract better around large objects such as mountains, but you'd have to ask an electrical engineer (or HAM radio guy) and they should be able to help you get the best out of your gear.

[Kingy]

I have my 27MHz on a six foot aerial and my FM radio on a six foot aerial. I think they are slightly different (they look exactly the same) but my FM aerial has FM sticker on it. Not sure if they are different aerials (different spiralling of the copper etc). But even with this I still have problems around the same spots as you (Juno, F/S). Therefore maybe a bigger aerial won't fix the prob for you.

I'm keen on an answer too, so come on all the raider smarties.

[Viking]

Hmm.

I have had this problem, and solved it, but only after spending a few bucks..

1.Bought a better marine radio with CD.

2.Installed a new antenna . 1 X FM & VHF with Splitter. (Bias). Note: Just changing the coax may also help as it can corrode / get damp and loose it's effectiveness over time.

3.As Joe said, create a ground plane by soldering a length of wire to the shield of the coax, and run it inside the boat.

4.Mount the Radio antenna as high as possible on the boat.

5.If all else fails, listen to a CD!

Cheers

[Guest Jocool]

3.As Joe said, create a ground plane by soldering a length of wire to the shield of the coax, and run it inside the boat.

Cheers

Maybe an elaboration of this point would be to connect the earth of the antenna to the negative bus bar. That would have wires radiating all over the boat, therefore enlarging the area of the ground plane you had formed.

The only issue could possibly be noise from the other electronics giving you static.

[Guest bluecod]

Wonder if the location of the transmitter has anything to do with it. Most of the CC FM station transmission antennaes are perched on top of Somersby, and between Juno and Lion you would be in shadow.

Edited November 4, 2005 by bluecod

[jewnut]

all i can tell you John is i pick up reception fine (i listen to Nova and have the same boat as you too), ive got a car stereo with marine speakers and 27meg aerial, buknow jack shit about electronics so cant explain why.

If all else fails, why not cruise in style to the relaxing sounds of AM...

[pirate pete]

In my efforts to catch larger fish I tended to wander a bit further out than I would normally and found the 6ft aerial on my 27meg radio not suited to my task, so after discussing my situation with GME I installed a AE96 8 Ft aerial I now have no problems with reception out to 26naut miles, I also have a band splitter into a GME 954 radio cassete player and since going to the larger aerial I have solved the reception problems on the FM.

Pete

[rebehy]

Hi TelcoBroker,

A couple of decades ago I used to be an electronics engineer and have done several hundred marine installations . I have seen some crazy things in my earlier years, so please indulge me if I ask you a couple of silly questions;

Are you using a marine antenna?

Where on the boat is it mounted?

is your coax corroded or still sealed water-tight?

Have you tried replacing your antenna (if it is a screw type) with a coathanger? (temporarily to check that the antenna is not corroded at the base) solder lugs don't like salt water even when covered in plastic.

If you can do a check and find that the cable and antenna are ok and you don't want to use a higher whip, or buy a unidirectional areal, you can usually fix this problem by mounting the antenna base on a metal ground plane. This ground plane only has to be around 40cmx40cm to be effective. use stainless steel or galvanized plate. I have done one in the past by using aluminium foil by making a fibreglass sandwich.

Make sure you check and double check your existing cables and installation before going to the trouble of making a ground plane (assuming you can access the underside of the antenna at all).

The Hawkesbury can be a problem because of the high hills either side of the river in parts.

Good luck.