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  Mounting VHF Antenna toward the Stern?

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Author Topic:   Mounting VHF Antenna toward the Stern?
kamie posted 01-15-2007 09:33 PM ET (US)   Profile for kamie   Send Email to kamie  
I realize there are several standard location for mounting the VHF antenna, among them, on the center console or on the gunnels directly opposite the helm. What if anything do I loose or gain by mounting the antenna on the support bar for the stern seat? Will this be too close to the outboard?

kamie.homelinux.org/kamie/html/evenstar.html

I am planning on getting a flying top, so console mounting is out, especially of two antenna. Second reason for considering this location because I don't really want to drill two more sets of holes in the gunnel (VHF & Cell). The standard gunnel location is also the only boarding location for the boat since the stern seat and grab rails block access toward the stern.
I also understand that I will need to lengthen the coax, since it seems that the coax for most 8 foot antenna's is only 15 feet long, which may or may not be long enough for a run from the port side, across the stern, thru the rigging tunnel and the into the console.

Thanks

Buckda posted 01-15-2007 09:40 PM ET (US)     Profile for Buckda  Send Email to Buckda     
Kamie -

There are two disadvantages that I can think of right away - the proximity to the motor charging current (RF interference) and the fact that you'll lose some antenna height in the process.

Actually, a third comes to mind - proximity to anyone sitting on the stern seat when you transmit...that kind of radiation may not be too good for soft tissue, such as eyes and internal organs...

Not that you're going to "cook" your passengers or anything, but still...

Dave

kamie posted 01-16-2007 07:07 AM ET (US)     Profile for kamie  Send Email to kamie     
Not sure I will really loose height except the extra gained by the motion of the boat. The stern seat rail is slightly higher than the gunnals.
As for cooking the passengers,not much different that putting them on the rails of the center console? Although, I do have a few "friends" I keep meaning to invite for a boat ride :)

I am worried about the closeness to the outboard. I might just have to try it out and see before I make the final decisions. I am a bit worried about clamping 8 foot antenna to the grab rails?

jimh posted 01-16-2007 08:59 AM ET (US)     Profile for jimh  Send Email to jimh     
From an electrical point of view, the location of the antenna in the stern and close to the outboard motor has these concerns:

--when receiving, the antenna is closer to the source of radio frequency noise from the engine's spark ignition and might pick up more interference;

--when transmitting, the antenna is closer to the engine's electronics and the radio frequency energy from the antenna may interfere with them.

Chuck Tribolet posted 01-16-2007 11:11 AM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
My antenna is mounted on the aft end of the starboard side
rail. No problems, but I have a fairly non-electronic
motor.

On my Montauk, I needed an antenna with a 20' coax. The
Shakespere Galaxy has a 20' cable. And is a pretty good
antenna.


Chuck

Tom W Clark posted 01-16-2007 11:40 AM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
Of far greater concern than noise or radiation is the interference to fishing activities. If you do not fish, do not worry about it.

Think about how the antenna will stow. This is one of the reasons why the gunwales are popular for mounting an antenna; it can lay down flat and relatively protected.

kamie posted 01-16-2007 03:02 PM ET (US)     Profile for kamie  Send Email to kamie     
Tom,
I considered that, and my though was I could stow the antenna either across the stern or depending on where I place it, I may be able to stow it forward along the gunnals. I don't trailer often so i could remove the antenna from the mount and store them in the rod holder for trailering.
Ultimatly if the location works, I may mount them to the gunnals past the grab rails, just want to know if works before making more holes in the teak.
sternorama posted 01-16-2007 05:43 PM ET (US)     Profile for sternorama  Send Email to sternorama     
I mounted my 8' whip on the rear railing of my 1968 16'. It is true that it obstructs the fishing area, but the mount ealisly allows for laying the antenna down flat to get it out of the way. I opted for this to keep clear of the bimini. No problems (that I am aware of) with being near the engine-seems to operate just fine..
Marlin posted 01-17-2007 01:17 AM ET (US)     Profile for Marlin  Send Email to Marlin     
Kamie, that's a pretty typical mounting location for sailboaters who don't want a mast-mounted whip. It works out okay, but in addition to Tom's fishing comments, aft quarter antennas are susceptible to damage from docklines and boarders who try to use them as a handhold.

-Bob

kamie posted 01-17-2007 06:58 AM ET (US)     Profile for kamie  Send Email to kamie     
Bob,
Given the only boarding location on Evenstar is farther forward putting them toward the stern, I hope, will save them from being used as a support. All boarding, either from the dock or from the water is done forward of the grab rails because of the stern seat.

kamie.homelinux.org/kamie/html/evenstar.html

bsmotril posted 01-17-2007 08:42 AM ET (US)     Profile for bsmotril  Send Email to bsmotril     
If you fish or water ski out of the boat, an antenna in the stern will become a big convenience. It will constantly be caught by ski ropes, fishing line, and lures.

BillS

Tom W Clark posted 01-17-2007 11:21 AM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
I guess I do not understand the resistance to just mount it at the forward end of the gunwale board and be done with it.

In this position it will lay forward or backward, clear any bimini or other running canvas, be fully supported when laying flat, be out of the way of fishing for the most part, be less likely to snag dock lines or ski tow ropes and be out of the driver's field of vision.

In addition, this position makes it very easy to route the coax to the console. The last point is one of the reasons we see antenna mounted in the stern of Montauks; it is very difficult to mount an antenna amidships on a Montauk and rout the coax cable to the console. On an Outrage, there is provision for this in the form of the small tunnels on each side of the hull.

kamie posted 01-17-2007 09:12 PM ET (US)     Profile for kamie  Send Email to kamie     
Tom, it may seem like the easiest thing to just mount the forward end of the gunnals, and ultimatly that maybe where they end up, but before I drill more holes, I want to confirm the location. I also want to explore alternate locations, good or bad. I especially don't want to commit until I have the boat in the water and I see how I am going to use her, now that the t-top is gone, the canvas will be up, ect.
The nice thing about the Outrage is you do have choices, assuming I mount them at the stern, I can still run the wires thru the rigging tunnel to the console, same idea mounting the midship.

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