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Author Topic:   Location of VHF Antenna
Albe posted 04-25-2007 08:31 AM ET (US)   Profile for Albe   Send Email to Albe  
I just took delivery of my new 190 Montauk this past weekend. I purchased the boat with the sun top (bimini) and conmsole cover options. When I came to pick up the boat I was surprised to see that the VHF (3 foot) antenna was installed on the deck of the boat directly next to the console. I had never seen an antenna in that location before and it looks kind of akward and out of place -- I thought it should have been mouinted on the console. The dealer said that he didn't mount it on the console because of the bimini and console cover. Does anyone have any experience with a (3 foot) antenna mounted on the deck and if so is the recption ok. Do you think I should press the dealer to move the antenna.
jimh posted 04-25-2007 12:17 PM ET (US)     Profile for jimh  Send Email to jimh     
On a small center console boat which does not have a radar arch, there are limited choices for the location of the mount for a VHF Marine Band vertical antenna. The greatest influence on how well the antenna will work is its height above the water. It is also very much preferred that the antenna be mounted in the clear, away from other parts of the boat, particularly any conductive structures. Mounting the radio antenna on the gunwale is the most common location.

Your description of the antenna as mounted to the "deck" is somewhat ambiguious. I am not sure if you are referring to the gunwale or to the cockpit deck, or, in a non-nautical term, the boat's cockpit floor.

If the antenna is mounted to the deck and not the gunwale, then I agree, that is an odd location, and, owing to the very low height and surrounding hull, will not be likely to give good results.

jgkmmoore posted 04-28-2007 03:30 PM ET (US)     Profile for jgkmmoore  Send Email to jgkmmoore     
I am to mount a 3' stainless mast on the console. The shortest antenna lead already made up was 12'. Dealer told me not to wad it up in a circle, wreath like fashion, but to flake it out inside the console in non overlapping 'S' turns.Right. The 18 OR doesen't lend itself to getting the antenna far from the radio. Is this necessary? Does it effect range, or sound quality? And, yeah, try to stick it to the inside of the console when you're upside down and backwards, and holding the flashlight in your mouth. I'm anal enough to not be able to just throw in in loose.Thoughts?
jgkmmoore posted 04-28-2007 03:33 PM ET (US)     Profile for jgkmmoore  Send Email to jgkmmoore     
PS- It is a Shakespear folding antenna, the mount bolted to stbd side of console.
bkloss posted 04-28-2007 08:18 PM ET (US)     Profile for bkloss  Send Email to bkloss     
I mounted an 8' fiberglass stick on the side of my console on a Dauntless 180 and have never had any problems. I get great reception and transmit power has never been an issue. I coiled my excess antenna cable as I agree, I am not a small person that can do figure 8's or s curves in the inside of my console.
jenkinsph posted 04-29-2007 02:17 AM ET (US)     Profile for jenkinsph  Send Email to jenkinsph     
If the antenna is mounted to the floor of the boat right next to the console and is a 3 foot antenna it is effectively at the waterline. This is the worst location they could have picked. Bet they wanted to get the boat out the door! How long before someone kicks or trips on it?

How important is the vhf to you? I ask this because it is simply a matter of priorities, you really should have more height and clearance to work best and you may need to make some compromises.

One idea with this short antenna is to be able to mount it straight down while stored higher up on the side of the console and then swing it up when in use. Need a ratchet mount for this. If the console cover is a tight fit you may need to modify it with a zipper or snaps ect. This is a quick fix or patch at best.

Jimh is more up to date on this than I am but in the old days when working for Motorola you could shorten the RG58 antenna cable to a minimum length of 3 feet. I would check with the manufacturer on this though.

On my own little boat I use a 4ft Shakespeare extension with a chrome plated stainless steel ratchet mount. It is
mounted to fold just below the top of the gunnel and this
allows me to flip the loaded coil antenna into a rod holder
out of the way when not is use. When the antenna is raised the base of the coil is just above the bimini top.
The radiating element is in the clear and out of touch.
This is good enough for a 150 Sport in the deserts of New Mexico.

If the vhf is a high priority for you then mount a ratchet
with an 8ft extension and coil with stainless whip closer to the stern and route the cable thru the tunnell to the console. Go to the trouble to use top quality cable for this with good shielding and impervious to chemicals ect.

Sorry to be so long winded, hope some of this helps.

Steve

Riverwhaler posted 05-04-2007 03:49 PM ET (US)     Profile for Riverwhaler  Send Email to Riverwhaler     
After going through my own initial idea that longer antenna was better I abandoned that for this. It is what JimH has been talking about except I mounted a Shakespear antenna because worst marine had it in stock. The extension is four foot which puts it pretty well over the head. It works very well talked 13 miles over North Haven Island to a sailboat in Rockport Harbor, Me. This is on a Nantucket.

jenkinsph posted 05-06-2007 01:38 AM ET (US)     Profile for jenkinsph  Send Email to jenkinsph     
Riverwhaler,

I have the same antenna and extension and have had good service too. The Shakespeare antenna is a good quality unit and is comparable to the GAM antenna. I was wondering if you thought to ask what the sailboat antenna height was? I would think it was near the top of the mast. The increased height really helps.

My suggestion for mounting was because of the bimini top on the original post. Without the bimini top I like the side console mounting since it allows fishing around the boat.

Steve

jimh posted 05-06-2007 12:07 PM ET (US)     Profile for jimh  Send Email to jimh     
The Shakespeare thee-foot whip antenna with base coil appears to be similar in its design to the Gam Electronics antenna I wrote about in

VHF Marine Band Antennas For Small Boats
http://continuouswave.com/whaler/reference/VHFAntenna.html

The Gam Electronics antenna is physically smaller, which may help reduce the wind loading on the extension mast and mount.

In general, as you might have guessed, I think:

-- that mounting the antenna as high as possible is the most important consideration;

--that you would like the antenna to not be in the way of normal activities on the boat such as fishing; and,

--that you would like the antenna to not be a hazard either physically (by poking you in the eye) or electrically (from exposure to a high level of radiation).

I think that mounting a smaller antenna on an extension mast satisfies all of these requirements.

In very simplistic terms, you can either put all of your 25-watts of power into the three-foot antenna, or you can split your power in an eight-foot antenna between its upper half, which is tall and in the clear, and its lower half, which is obstructed by the boat, the console, railings, and people. I would rather have all of my radio power going into the smaller antenna mounted higher.

On a small boat which has a bimini top another option for an antenna mounting base location is the railing of the bimini top's frame. If the frame is stainless steel, you may be able to use a clamp mount to fasten an antenna mounting base. A three-foot antenna mounted to such a base would satisfy all of the requirements mentioned above

bigjohn1 posted 05-07-2007 03:38 AM ET (US)     Profile for bigjohn1  Send Email to bigjohn1     
Here is another idea which I don't think has been mentioned. Use a heavy duty rail mount and mount it as far forward as possible on the forward rail. I did this on a 170 Montauk which is very similar to your 190 Montauk. I chose this location to avoid any physical interference betweeen the antenna itself and the bimini frame (I always use the bimini to avoid the strong tropical rays) and also to avoid any signal loss due to the radiating antenna being right next to the ss bimini frame. I also chose the forward location due to needing the entire aft section of the boat to be clear for fishing.

If you don't fish, what about mounting an 8 footer back aft on the starboard gunnel (or via the aft rail), then you can run the coax up forward by hiding it inside the rigging tunnel.

One drawback to my forward location mentioned above is
the coax must be zip-tied to the forward rail and ran back to the end of the aft rail where it is parrellel to the console. The coax is then run down and across the deck and routed into the console. I bought a 12" length of "cable ramp" (the stuff you use when running extension cords across heavy foot traffic areas) to hide the coax running across the deck. Just another idea.....

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