VHF Installation !9' runabout

[explorer1]

Hello to All


Getting around to buying/installing a VHF on our 2008 Bayliner 195 Discovery. I'm looking for comments/suggestions on what I propose.

The components:

ICOM M422 Submersible DSC VHF Radio

ICOM Command Mic II

Morad VHF-156FG Fiberglass VHF 6dB gain whip antenna

West Marine Stainless Steel Rail Mount - with Lever



The installation:

Mount the M422 underneath the dash. This due to the lack of space on the dash.

Use the Command Mic II hung on or near the starboard side of the dash to for control/use of the M422.

Use the rail mount to affix the antenna to the bimini frame close to the bimini top. The antenna weighs only 2.5 lbs so it would seem to pose no significant strain on that structure and would position the antenna as high as possible on the boat. Haven't measured exactly, but would probably put the antenna ~ 12' above the waterline. Run the coax down the bimini frame (plastic ties),along and under the gunwale to the radio.


I like the Morad as its 1.25 to 1 SWR is better than Shakespeare's 1:50 to 1 and it's lighter and appears better suited for a 19' runabout. The levered rail mount would allow the antenna to stow on the gunwale with the bimini down or to allow use of the antenna (diminished ht/range) with the bimini down.

Any comments/suggestions appreciated.

Thanks

Explorer1

 

[NYBo]

Re: VHF Installation !9' runabout

It's deja vu all over again!

While higher is better, I wouldn't mount the antenna to the bimini. It's not the weight that's the problem, it's the air resistance force at speed that may break the bimini pole or its mount. The higher the mounting point, the more leverage there will be on the mount.

 

[ziggy]

Re: VHF Installation !9' runabout

yep, me personally, for antenna mount, i didn't even like the idea of rail mount to one of the rails on my boat, let alone on a bimini....

i went ahead had drilled the holes in my boat for an antenna base (and i'm real opposed to drilling holes in my boat too). 4 ea. 1/4-20 ss screws with ss fender washers and nylok nuts. that makes me feel my antenna ain't going no where while underway (i got a 8'er). it also lays down on the gunnel.. take the plunge and mount it solid... imho...

i also did a pass through hole for the antenna cable right next to the antenna base. used a rubber grommet to seal the pass through hole. exposed cable is only a few inches on the outside, then gone inside the boat. out of sight inside the boat is a + too...again, imho..

 

[Triton II]

Re: VHF Installation !9' runabout

Personally I'd also avoid a rail mount. A quick knock down mount like this one is stronger and allows the antenna to fold backwards under the boat cover when she's not on the water. I can adjust the rake easily from the driving position and the lateral angle is adjustable to keep the antenna vertical in relation to the cabin side. You can also use this type of mount horizontally on your deck. You can get 6ft or 9ft versions and they're not expensive.

 

[ziggy]

Re: VHF Installation !9' runabout

....

You can also use this type of mount horizontally on your deck.

yep, that's the way mine ended up

antenna folds down flat on top of the gunnel.

both these type of installs look solid and proper to me...

 

[Boatist]

Re: VHF Installation !9' runabout

My first antenna I tried a rail mount up on the front deck just foward of the windsheild. About every 3rd or 4th trip I would hit a wave and it would lean to one side or the other. I tried shims to tighten it up but did not help so went a deck mount with large stainless washer under the deck and a stainless steel mount.
Works great from then on.

My bow rails are 1 inch Aluminum. If they were Stainless Steel I think they would
have worked with shimms and or some type of glue. After a week or so never ever had to think about the 4 holes I drilled.

 

[explorer1]

Re: VHF Installation 19' runabout

Re: VHF Installation 19' runabout

Thanks to all for your replies. They make a strong case for not using a rail mount on my bimini frame. The photos helped; I'll go with something similar to the mountings shown. The only downsides I can see with the deck or gunwale mounts are the lower antenna height (range reduction) and the small visual obstruction of the antenna mast (probably unnoticed after a couple of trips).

If my calculations are correct, the range--given everthing else in order-- between two stations with antennas 12' above waterline is ~8.2 miles; between two stations with antennas 7' above waterline ~6.3 miles. Since the USCG here in So.Calif. has shoreside antenna heights of 300'(range between 7' high boat antenna and 300' USCG= ~24mi) , 2000' and higher, it wouldn't seem the lower boat antenna height is significant when calling for help from a 19' runabout's probable offshore cruise limit/use.
Haven't had any experience with this so comments are appreciated.

Thanks again,

explorer1

 

[Triton II]

Re: VHF Installation !9' runabout

You may gain a few feet or so in antenna height by using a bimini mount over a deck mount, but even so, you won't notice much difference in range shore-to-ship so I'd fit a 9ft antennae in the most convenient and strongest place on the boat. A solidly mounted antennae on a really rough day will stay upright, whereas there's always the risk that a railmount will rotate when the going gets tough. The extra height by going bimini rail mount is worthless if the antenna won't stay upright and getting someone to hang onto the antenna to hold it upright in big seas/winds in an emergency is not going to help in a safety sense... MOB is frightening! The "blanking" from the cabin of the lower part of the antenna on my boat (see pic above) doesn't seem to affect range or clarity of tx/rx either. As suggested above, stick to a solid mount system - you won't be sorry. Just my .02c...

 

[Boatist]

Re: VHF Installation !9' runabout

My boat with a 8 foot antenna mounted on the deck about 3 feet above the water get a range to other boats like mine of about 10 miles.

Buy a good quality antenna Like a shakespers 5225 and it will last a long time.

If you want more height you can add antenna extensions also form Shakespears. They come in 2 feet, 4 feet, and 8 feet. They also have different qualities some match the Galxy series like the 5225. The centers are hollow so you can run the coax down the center of the extension. If you use a extension of more that 2 feet I would suggest a support to the top of your window to take the strain off the deck and mount.
Your distances are pretty close. I think you may get just a little more.
I fish offshore out of bodega bay 50 miles North of San Francisco. I have run 30 miles farther north so about 80 miles North of San Francisco and still been able to talk to Coast Guard Group San Francisco.

San Francisco Group Has at least 6 antennas and one is on top of mount Tamalipias or about 3000 feet high. I would bet Southern California also has some antenna mounted higher than 300 feet along the coast.

http://shakespeare-marine.com/faq2.asp?ReqNum=9

http://shakespeare-marine.com/ovr-extension.asp

http://shakespeare-marine.com/specs.asp?menupick=galaxy_extension

 

[jhebert]

Re: VHF Installation !9' runabout

I prefer the Standard-Horizon VHF Marine Band radios in preference to ICOM radios because:

--Standard-Horizon radios have better modulation quality on transmit
--Standard-Horizon radios have better digital selective calling features
--Standard-Horizon radios generally cost less on a feature-for-feature basis

I recommend you get a VHF Marine Band radio that is rated as a CLASS-D DSC radio. The United States Coast Guard also makes this recommendation. The Standard-Horizon GX1500S is a CLASS-D DSC radio and sells for about $150. This is considerably less expensive than any ICOM radios with similar rating.

The controls and presentation of the digital selective calling features on a Standard-Horizon radio are generally more logical and easier to use than on ICOM radios.

The transmitter modulation of Standard-Horizon radios is generally better than most other VHF Marine Band radios. I formulated this opinion by listening to many hours of radio traffic and by asking stations which had exceptionally good sounding radios to identify the brand. Most often the good sounding radios were from Standard Horizon. ICOM radios in general tend to have poor modulation quality, often very tinny and difficult to copy.

The MORAD-brand antennas appear to be very good antennas. They are not nearly as well known, as widely distributed, or as popular as other brands, but their reputation is excellent.

In a small boat the location and mounting of the VHF Marine Band radio antenna is always a compromise between optimizing for radio range and staying out of the way for the boat crew. After considering this problem in my own boat, I use a three-foot metal whip antenna mounted on a four-foot extension mast. See details of my installation at

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