Radio Aerial mounting in Plastic Boat

[lezmtaylor]

Can anyone help me?

I have a 26 foot Conway GRP Cabin Cruiser which is moored on the Avon at Bredon Marina Near Tewkesbury, Glos.

I am fitting a new am/fm radio.

My problem is poor reception, I have fitted a new aerial and still not much good, do you have to fit seperate earth connection from the aerial to the radio unit ( as there is no chassis /metal to mount the aerial I would imagine some sort of earth/ground wire would be required, as it is GRP construction)

Thanks.

Lez

[RobinJ]

I have a 26 foot Conway GRP Cabin Cruiser which is moored on the Avon at Bredon Marina Near Tewkesbury, Glos.

I am fitting a new am/fm radio.

My problem is poor reception, I have fitted a new aerial and still not much good, do you have to fit seperate earth connection from the aerial to the radio unit ( as there is no chassis /metal to mount the aerial I would imagine some sort of earth/ground wire would be required, as it is GRP construction)

What sort of aerial?

Where exaclty is it being fitted?

If its a normal car type aerial, there are designed to be mounted onto metal panels with a coax or twin cable feed. On a GRp boat there are a couple of ways to get round this, fit a metal plate/washer onto the underside of the fitting, if the area of ground plane needs to be increased I have seem a layer of aluminium foil being glued on the inside of the roof!

[lezmtaylor]

What sort of aerial?

Where exaclty is it being fitted?

If its a normal car type aerial, there are designed to be mounted onto metal panels with a coax or twin cable feed. On a GRp boat there are a couple of ways to get round this, fit a metal plate/washer onto the underside of the fitting, if the area of ground plane needs to be increased I have seem a layer of aluminium foil being glued on the inside of the roof!

Hi there,

Yes it is a standard car type aerial, side fitted to the windscreen upright, it is fitted with the standard coax cable with a plug on the end.

The screw that fixes it to the upright would I imagine normally earth it to chassis ( I can see the metal earth washer /conn thatthe screw makes contact with as it tightens the aerial the the frame ) I have attached a flying lead to under the screw where should I connect the other end to , to get the earth connection.

Or am I barking up the wrong tree ?

Lez

[RobinJ]

Yes it is a standard car type aerial, side fitted to the windscreen upright, it is fitted with the standard coax cable with a plug on the end.

The screw that fixes it to the upright would I imagine normally earth it to chassis ( I can see the metal earth washer /conn thatthe screw makes contact with as it tightens the aerial the the frame ) I have attached a flying lead to under the screw where should I connect the other end to , to get the earth connection.

Or am I barking up the wrong tree ?

If you do it that way then it should be grounded to your hull connection if you have one!

Going that route you may end up with some galvanic issues (depending on what propellor/motive power you have)?

[pearley]

Putting a ground on the aerial won't make any improvement in reception, however it should prevent interference from the engine and other eltrical apparatus on the boat.

[lezmtaylor]

The drive is 2x 130c volvos attached to 2x volvo 270 outdrives.

Thankyou for your suggestions, will be on the boat Tuesday.

regards,

Lez

[Radio-Ga-Ga]

An aerial needs two "halves", fitted on a car the metal acts as a ground plane, in your situation the easiest way to add the missing half is to connect a wire to the coax braid at the aerial end, the thickness of the wire is not important the length should be the same as the length of the aerial when fully extended, there is no point in earthing on a plastic boat. if you mainly listen to one radio station tune to it then push the aerial shorter in stages till you get the best reception and cut the wire connected to the coax to the same length, finally you might be able to tuck the wire into the windscreen rubber or surround. Your aerial will be working as a dipole rather than its original design - a ground plane, the only problem you might find is your own proximity may affect reception.

[WotEver]

If you do it that way then it should be grounded to your hull connection if you have one!

Going that route you may end up with some galvanic issues (depending on what propellor/motive power you have)?

OP's unlikely to have too much of a galvanic corrosion problem on his GRP hull