Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 15-01-2016, 17:25   #31
Registered User

Join Date: Dec 2013
Location: Sausalito, CA
Boat: Ericson 35 MKII
Posts: 33
Re: What is the range of a handheld vs an integrated DSC VHF?

I'm probably going to go with the fixed-mount option for DSC, then just a regular old hand held VHF in case something happens to the mast.

But this makes me wonder...

What's really the difference between having DSC rescue capabilities versus an ePirb? Obviously an epirb works with satellite coverage, but if you are nearby a station, would DSC simply have a faster reaction time from search and rescue?

I do tend to go overboard with safety equipment, but I think that's an okay splurge.
__________________

__________________
Freyja's Adventures in NorCal:
http://kingtidesailing.blogspot.com/
TBillings is offline   Reply With Quote
Old 15-01-2016, 17:57   #32
Registered User
 
buzzstar's Avatar

Join Date: Apr 2012
Location: ashore in So Calif.
Boat: No more boat (my medical, not the boat's)
Posts: 1,269
Re: What is the range of a handheld vs an integrated DSC VHF?

Call the CG on your handheld while you are in the Bay and ask. My guess, and it is just that, is there is a reasonable chance they have plenty of experience with it working, but of course cannot guarantee it. Also, you are near a high traffic area, and you message can be passed on to the CG in an emergency setting, and you would have no reason to call the CG except pan, securite or mayday situations.
__________________

__________________
"Old California"
buzzstar is offline   Reply With Quote
Old 15-01-2016, 20:48   #33
Registered User
 
Jon Hacking's Avatar

Join Date: Sep 2010
Location: Currently cruising Southern Indonesia, heading for peninsular Malaysia
Boat: Wauquiez 45' (now 48') catamaran
Posts: 523
Send a message via Skype™ to Jon Hacking
Re: What is the range of a handheld vs an integrated DSC VHF?

Quote:
Originally Posted by MatthewDurst View Post
...What's really the difference between having DSC rescue capabilities versus an ePirb? Obviously an epirb works with satellite coverage, but if you are nearby a station, would DSC simply have a faster reaction time from search and rescue?
EPIRBs do have a much longer chain of events to traverse. Signal to satellite to ground station (NOT the CG) where they look up your registered "contact" person. They call this person & based on their reply ("I dunno, I thought he was out shopping" or "he's in the middle of hurricane Henry") they may call out the cavalry to come rescue you. So it could take some time for things to really get moving, & they won't know what your problem is or what help you need. They don't always call the cavalry immediately as EPIRBs sometimes go off accidentally (hitting the switch while cleaning up down below, for instance). Good EPIRBs also cost about a Boat Buck ($1,000) & need their batteries professionally serviced every 7 years or so.

VHFs are not only cheaper, but if you're only sailing around SF Bay, you'll be talking directly to the very folks you want to, & giving them the info they need (where you are, your situation, what you need, etc). Much faster & more efficient. The major downside is that YOU will be the one having to talk (which can be difficult if you're alone & having to man the pumps yourself, but that's what the Emergency switch is for).

Personally, I would consider an EPIRB for SF Bay a bit of an extravagance, & I'd probably spend that $$ elsewhere first (like an AIS) but others would probably disagree. Certainly I'd get a good VHF before I'd get an EPIRB if I was just having fun around the Bay.
__________________
-- Jon Hacking s/v Ocelot
Jon Hacking is offline   Reply With Quote
Old 15-01-2016, 21:50   #34
Registered User

Join Date: May 2013
Location: San Francisco Bay, California
Boat: Pacific Seacraft 37
Posts: 105
Re: What is the range of a handheld vs an integrated DSC VHF?

Quote:
Originally Posted by MatthewDurst View Post
...What's really the difference between having DSC rescue capabilities versus an ePirb? Obviously an epirb works with satellite coverage, but if you are nearby a station, would DSC simply have a faster reaction time from search and rescue?

I do tend to go overboard with safety equipment, but I think that's an okay splurge.
A standard for equipping a sailboat for the nearshore ocean is the NorCalORC Safety Equipment Requirements as adapted/modified for the various yearly Farallon Races.

See here:

http://sfbaysss.org/main/wp-content/uploads/2015/01/US-SER-2015.0-NCORC.pdf

In 2015, these required a 25 watt masthead DSC VHF, a DSC VHF handheld and an EPERB or PLB, all GPS enabled for races to the Farallons.
__________________
The Smokester is offline   Reply With Quote
Old 15-01-2016, 22:05   #35
Senior Cruiser

Cruisers Forum Supporter

Join Date: Mar 2007
Location: Santa Cruz
Boat: Boatless Again
Posts: 4,321
Re: What is the range of a handheld vs an integrated DSC VHF?

The DSC vhf will get help a lot faster than an epirb, which didn't work well in this case:

Yacht sinks outside Golden Gate
__________________
donradcliffe is offline   Reply With Quote
Old 16-01-2016, 03:08   #36
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: Cowes (Winter), Baltic (Summer) (the boat!); somewhere in the air (me!)
Boat: Cutter-Rigged Moody 54
Posts: 19,743
Re: What is the range of a handheld vs an integrated DSC VHF?

Quote:
Originally Posted by estarzinger View Post
.. ..

On the more general question, I have always been interested and somewhat puzzled by the 'vhf range' question. On the one hand people say it is all about radio line of sight and that you can hear a 1 watt signal back from the moon. But on the other hand, we all know that the low power setting on our radios does in fact seriously cut their range (even using the same masthead antenna) and handhelds typically have really limited range. So, it has always seemed to me that it is in fact not 'all about line of sight' and that power (including antenna gain) does in fact matter significantly to effective transmit range. But I have never seen a range calculator that captured this.
There's no "range calculator" because VHF range depends on so many different factors. Nominal power output of the radio is not a good guide, because there are so many things between that and the real radiated RF power as actually received by your correspondent, especially your antenna and his antenna, but also the cabling and connectors (in which it would not be unusual to lose 90% of the radio's power), and even atmospheric conditions.

Contrary to popular belief, VHF is not strictly line of sight, but usually reaches a bit over the horizon. VHF is also subject to different tropospheric propagation effects (see: https://en.m.wikipedia.org/wiki/Trop...ic_propagation).

But the most important single factor is the antennae involved. Radio enthusiasts often say that radio is 90% antenna, and 10% radio.

So you see there couldn't be a calculator; there are too many factors. As a rough guide, all but the poorest fixed mount VHF radio installations should give good comms with the Coast Guard (taking the correspondent's antenna and antenna height out of the equation) at at least 30 miles, and with a half decent antenna and cabling, 50 miles.

Between two sailboats, it's just about impossible to give any even rough rule of thumb.

The best advice for better VHF comms is to pay attention to the antenna, cabling, and connectors. At VHF frequencies, there's a lot of attenuation over 25 meters (or whatever) of cabling, so it really pays to use fat, low loss cable like RG213, if it will fit in your mast, to be careful to install it without nicks or kinks, and to use the minimum number of very carefully installed, high quality, carefully waterproofed connectors (preferably Type "N" for any other than the radio connection). One sloppily soldered connector will ruin the whole installation.

And of course the antenna. I use a Galaxy silver-plated internal dipole, recommended to me by someone on this board.

I also have a Japanese dual-band VHF/UHF antenna on my first spreader which I use for AIS and for ham VHF/UHF, which likewise serves as backup to the main VHF antenna.

With a good antenna, well installed, you can leave the radio set on 1 watt output most of the time.


Sent from my D6633 using Cruisers Sailing Forum mobile app
__________________
"Parce que je suis heureux en mer, et peut-Ítre pour sauver mon ame. . . "
Dockhead is offline   Reply With Quote
Old 16-01-2016, 04:05   #37
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: Cowes (Winter), Baltic (Summer) (the boat!); somewhere in the air (me!)
Boat: Cutter-Rigged Moody 54
Posts: 19,743
Re: What is the range of a handheld vs an integrated DSC VHF?

P.S., to show the importance of cabling:

If you put 25 watts of RF power, at VHF frequencies, into one end of 25 meters of RG213 coax, 15 watts comes out the other end.

If you are using RG58 -- then it's 9 watts.

That is assuming cable in perfect condition, perfectly installed, and that does not include insertion loss of the connectors.

UHF connectors as typically used in marine VHF installations (SO239/PL259 pairs) are the worst coax connectors in the world, sucking out about 1 dB of signal each (see: 'UHF' Connector Test Results).

You can't avoid having one pair of these at the radio itself, as this it the universal antenna connector for consumer grade marine VHFs, but UHF connectors should be eliminated everywhere else if possible. In my installation, I have a single "N" type connector at the masthead, waterproofed using a "telecomm wrap", and no connector at all at the base of the mast -- just solid coax all the way to the nav table.
__________________
"Parce que je suis heureux en mer, et peut-Ítre pour sauver mon ame. . . "
Dockhead is offline   Reply With Quote
Old 16-01-2016, 04:43   #38
Senior Cruiser

Cruisers Forum Supporter

Join Date: Jul 2006
Location: Chesapeake Region and Maine
Boat: 42' Bob Perry sloop
Posts: 4,038
Images: 4
Re: What is the range of a handheld vs an integrated DSC VHF?

I certainly agree that choice of coax is important, particularly at VHF frequencies like the marine band (156-160mHz or so).

RG-8 and RG-58 should NOT be used, unless absolutely necessary. RG-213 or RG-214 and RG-8X are much better choices. LMR-400 and the smaller LMR-240 are even better to reduce signal loss in the coax.

The deficiency of PL-259/SO-239 connections is well known. However, recent research suggests that the actual losses at marine VHF frequencies are much less than many earlier citations, more on the order of 0.2db not 1db.

It's instructive that virtually all manufacturers of VHF equipment -- even VHF repeaters -- employ PL-259/SO-239 connections.

What to do?

1. Use the best coax for the job;
2. Use the best "UHF" connectors -- PL-259/SO-239 -- you can find, not the cheapo connectors generally available
3. Be absolutely sure the connectors are properly installed
4. Waterproof the connections as best you can -- tape, adhesive shrinkwrap, etc.
5. Choose a high-quality VHF antenna

As to which choice, fixed or handheld, that's easy:

- IMHO, every boat should have a quality fixed VHF radio installed, PERIOD. This is not a big investment in $$$, but certainly is a big investment in safety

As to EPIRBs, IMHO every boat venturing offshore should have a good EPIRB, preferably one with an internal GPS. Maybe in Indonesia they cost $1,000 but they cost much less these days in the U.S. I bought one in May 2015 for $357 new (price included a $75 rebate). This was the ACR EPIRB MODEL 2644 W/GPS.

Here it is, right next to my chartplotter screen.

Click image for larger version

Name:	EPIRB.jpg
Views:	59
Size:	202.9 KB
ID:	116806

Bill
__________________
btrayfors is offline   Reply With Quote
Old 16-01-2016, 04:49   #39
Registered User
 
Ziggy's Avatar

Join Date: Apr 2008
Location: U.S., Northeast
Boat: Contessa 32
Posts: 1,421
Images: 2
Re: What is the range of a handheld vs an integrated DSC VHF?

Quote:
Originally Posted by Chuck Hawley View Post
Great question! You're not actually talking to the Coast Guard stations, but rather to an antenna on the top of Mt. Tam, and an operator who is at Yerba Buena Island in the Bay. The Coast Guard's Rescue 21 system will pick you up at the Farallones (not on the back side, but either side) with a handheld radio that's 2m above the water, or so the specification says. So, if your only task was to talk to the Coast Guard, then a handheld VHF especially with DSC, would do the job.

However...

If you want to talk to other vessels, or shore stations that don't have an antenna on Mt. Tam, you'd be much better off with a fixed mount radio and a quality antenna installation on your masthead. Figure 2 miles transmission with the handheld to another sailboat, and perhaps 20 miles with your fixed mount antenna.

And the vessel that comes to your aid might be just another gal or guy who's taking a sail about SE Farallon and Maintop Islands.

Finally, yes, there is a good reason to also carry a PLB or EPIRB, and that is their independence from all of your vessel systems. You can sink, lose your mast, have a fire, run your batteries down, etc and the PLB or EPIRB still works.

Cheers,

Chuck Hawley
I agree with everything in Chuck's post. By the way, there is a nice USCG map showing coverage of the Rescue21 system. Note that it is for a 1 W radio and an antenna 2 meters (6 feet) above the water:
__________________
... He knows the chart is not the sea.
-- Philip Booth, Chart 1203
Ziggy is offline   Reply With Quote
Old 16-01-2016, 04:54   #40
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: Cowes (Winter), Baltic (Summer) (the boat!); somewhere in the air (me!)
Boat: Cutter-Rigged Moody 54
Posts: 19,743
Re: What is the range of a handheld vs an integrated DSC VHF?

Quote:
Originally Posted by btrayfors View Post
I certainly agree that choice of coax is important, particularly at VHF frequencies like the marine band (156-160mHz or so).

RG-8 and RG-58 should NOT be used, unless absolutely necessary. RG-213 or RG-214 and RG-8X are much better choices. LMR-400 and the smaller LMR-240 are even better to reduce signal loss in the coax.

The deficiency of PL-259/SO-239 connections is well known. However, recent research suggests that the actual losses at marine VHF frequencies are much less than many earlier citations, more on the order of 0.2db not 1db.

It's instructive that virtually all manufacturers of VHF equipment -- even VHF repeaters -- employ PL-259/SO-239 connections.

What to do?

1. Use the best coax for the job;
2. Use the best "UHF" connectors -- PL-259/SO-239 -- you can find, not the cheapo connectors generally available
3. Be absolutely sure the connectors are properly installed
4. Waterproof the connections as best you can -- tape, adhesive shrinkwrap, etc.
5. Choose a high-quality VHF antenna

As to which choice, fixed or handheld, that's easy:

- IMHO, every boat should have a quality fixed VHF radio installed, PERIOD. This is not a big investment in $$$, but certainly is a big investment in safety

As to EPIRBs, IMHO every boat venturing offshore should have a good EPIRB, preferably one with an internal GPS. Maybe in Indonesia they cost $1,000 but they cost much less these days in the U.S. I bought one in May 2015 for $357 new (price included a $75 rebate). This was the ACR EPIRB MODEL 2644 W/GPS.

Bill
The master has spoken; Bill forgot yesterday more about radio than I'll ever know.

One tiny comment -- LMR400 and LMR240 cable is foam core. This was always considered to be unsuitable for marine use because of the risk of water getting into it. I think the water issue has been somewhat debunked now, but I still wouldn't use it in a mast -- because the foam can be compressed where the cable is run against something metallic, which will screw everything up.

I use RG213/U for my VHF radios (and HF also), which is the multistrand (and thus very flexible) version of RG213, slightly higher attenuation than LMR400, but with a tough core which cannot be easily compressed, and which is probably more waterproof to boot.

I do use LMR400 for my ham VHF/UHF radio. This is not mission critical, so the risk of insulator problems doesn't bother as much, and besides the amount of attenuation goes way up at UHF frequencies, so the advantages of LMR400 are greater.
__________________
"Parce que je suis heureux en mer, et peut-Ítre pour sauver mon ame. . . "
Dockhead is offline   Reply With Quote
Old 16-01-2016, 05:23   #41
Registered User

Join Date: Apr 2006
Posts: 4,413
Re: What is the range of a handheld vs an integrated DSC VHF?

Quote:
Originally Posted by Dockhead View Post
The master has spoken; Bill forgot yesterday more about radio than I'll ever know.

One tiny comment -- LMR400 and LMR240 cable is foam core. This was always considered to be unsuitable for marine use because of the risk of water getting into it. I think the water issue has been somewhat debunked now, but I still wouldn't use it in a mast -- because the foam can be compressed where the cable is run against something metallic, which will screw everything up.

I use RG213/U for my VHF radios (and HF also), which is the multistrand (and thus very flexible) version of RG213, slightly higher attenuation than LMR400, but with a tough core which cannot be easily compressed, and which is probably more waterproof to boot.

I do use LMR400 for my ham VHF/UHF radio. This is not mission critical, so the risk of insulator problems doesn't bother as much, and besides the amount of attenuation goes way up at UHF frequencies, so the advantages of LMR400 are greater.
Compression against a metal part inside the mast? Explain that one. Sure if you can some how cable tie and over tighten you would conceivably compress and perhaps damage. I find this unlikely. The other possibility is a bend or turn rubbing/pressing against a mast exit hole. Possible but can be mitigated by a rubber grommet and a decent sweep to the curve... if possible rather than a hard bend.

Water intrusion can be mitigated by proper heat shrink sealing of the connector to the cable jacket. And after a connection is made... you can heat shrink the connection too.

Obviously an important consideration is to mitigate loss of signal... so this should guide the decisions in selecting the bits from the radio right to the antenna itself.

Someone needs to make a nice spread sheet comparing the options with actual products used including cost!
__________________
Sandero is offline   Reply With Quote
Old 16-01-2016, 07:12   #42
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: Cowes (Winter), Baltic (Summer) (the boat!); somewhere in the air (me!)
Boat: Cutter-Rigged Moody 54
Posts: 19,743
Re: What is the range of a handheld vs an integrated DSC VHF?

Quote:
Originally Posted by Sandero View Post
Compression against a metal part inside the mast? Explain that one. Sure if you can some how cable tie and over tighten you would conceivably compress and perhaps damage. I find this unlikely. The other possibility is a bend or turn rubbing/pressing against a mast exit hole. Possible but can be mitigated by a rubber grommet and a decent sweep to the curve... if possible rather than a hard bend.

Water intrusion can be mitigated by proper heat shrink sealing of the connector to the cable jacket. And after a connection is made... you can heat shrink the connection too.

Obviously an important consideration is to mitigate loss of signal... so this should guide the decisions in selecting the bits from the radio right to the antenna itself.

Someone needs to make a nice spread sheet comparing the options with actual products used including cost!
Yes, if the cable is pulled hard against something hard inside the mast, or for example the edge of the hole in the mast where it comes out at the masthead. If the foam is compressed, then the shield and core will not be held at the appropriate distance from each other and the signal will be degraded or completely interrupted.

How likely is that to happen? I can't say, but I wouldn't, personally risk it, for the primary VHF antenna cable. Not worth the risk, for the difference of only 1.3 dB of attenuation at VHF frequencies. That's over 30 meters of cable; the difference is less for shorter cable runs.

That being said, I did use LMR400 for the VHF/UHF ham radio antenna. At UHF frequencies, the difference to RG213 is more like 2.4 dB (a huge difference since dB is a logarithmic scale), so much more noticeable. And besides that, the ham radio is not mission critical.
__________________
"Parce que je suis heureux en mer, et peut-Ítre pour sauver mon ame. . . "
Dockhead is offline   Reply With Quote
Old 16-01-2016, 07:22   #43
Registered User
 
hamburking's Avatar

Join Date: Feb 2013
Location: Kingston Ont Canada
Boat: Looking for my next boat!
Posts: 2,148
Re: What is the range of a handheld vs an integrated DSC VHF?

Quote:
Originally Posted by thomm225 View Post
So if you climb to the top of your mast when using your hand held it would be better but still have less range than your mounted VHF due to lower power.
If you have a bad cable/connections to the masthead antenna, then your climbing option would definitely have greater range. The cable losses can easily consume almost all the power put out by the radio. And this is assuming you have house batteries (and suitable wiring) to provide the electrical power to transmit at 25watts.
__________________
hamburking is offline   Reply With Quote
Old 16-01-2016, 07:57   #44
CF Adviser

Cruisers Forum Supporter

Join Date: Aug 2009
Boat: Custom Van De Stadt 47 Samoa
Posts: 3,743
Re: What is the range of a handheld vs an integrated DSC VHF?

Quote:
Originally Posted by Dockhead View Post
So you see there couldn't be a calculator; there are too many factors.
Honestly it does not sound all that complicated or difficult for a calculator.

The 4 primary input factors would be vhf output power, cabling and connector loss, antenna gain and antenna height.

You could have a sub-calculator to help figure the cable and connector loss, which would have pre-loaded factors for the most common coax and connector types and you would just put cable length and type and number and type of connectors in and get out a power loss number.

What I have never heard anyone state is what is the receive sensitivity of our consumer grade vhf's - eg his much of a signal do they need for you to be able to "hear it". I suppose that has to do both with the radio electronics and environmental noise/static in your specific area. The calculator would need a cut off: below this signal level and above this noise you can't hear it anymore.

Finally my understanding is that you might have a "geographic factor" for the signal path - open water. Flatish coastal water, hilly, (and perhaps urban would fit in there somewhere). Probably makes sense to start with the open water case.

None of this sounds all that difficult. I think one of our radio buffs here could do a service to the community to build the community a little calculator. Because the commonly stated "radio line of sight" formula obviously is mis-leading and does not tell the full practical real world story. The calculator would of course not be absolutely 100% accurate, as none are (because at base level we don't actually understand physics), but it would be quite a bit more useful in answering the OPs sort of very commonly asked question.

I should note that I once worked with a us military signal calculator like this, but it was not for vhf's and not for commercial equipment, and it is not publicly available. But it has and can be done.
__________________
estarzinger is offline   Reply With Quote
Old 16-01-2016, 08:04   #45
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: Cowes (Winter), Baltic (Summer) (the boat!); somewhere in the air (me!)
Boat: Cutter-Rigged Moody 54
Posts: 19,743
Re: What is the range of a handheld vs an integrated DSC VHF?

Quote:
Originally Posted by estarzinger View Post
Honestly it does not sound all that complicated or difficult for a calculator.

The 4 primary input factors would be vhf output power, cabling and connector loss, antenna gain and antenna height.

You could have a sub-calculator to help figure the cable and connector loss, which would have pre-loaded factors for the mist common coax and connector types and you would just put cable length and type and number and type of connectors in and get out a power loss number.

What I have never heard anyone state is what is the receive sensitivity of our consumer grade vhf's - eg his much of a signal do they need for you to be able to "hear it". I suppose that has to do both with the radio electronics and environmental noise/static in your specific area. The calculator would need a cut off: below this signal level and above this noise you can't hear it anymore.

None of this sounds all that difficult. I think one of our radio buffs here could do a service to the community to build the community a little calculator. Because the commonly stated "radio line of sight" formula obviously is mis-leading and does not tell the full practical real world story. The calculator would of course not be absolutely 100% accurate, as none are (because at base level we don't actually understand physics), but it would be quite a bit more useful in answering the OPs sort of very commonly asked question.
Gain is only one quality of antenna systems, and not the most important one.

Naturally, you could build a calculator such as the one you suggest, but query whether it could have enough relationship to reality to be anything but misleading -- I don't know.
__________________

__________________
"Parce que je suis heureux en mer, et peut-Ítre pour sauver mon ame. . . "
Dockhead is offline   Reply With Quote
Reply

Tags
dsc, vhf

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
[SOLD] still in the box waterproof Icom Handheld VHF model: IC-M92D Class D DSC with GPS Matt Y Classifieds Archive 4 15-09-2015 19:43
Looking for a fixed VHF *without* DSC (or ability to disable DSC) susswein Marine Electronics 31 10-11-2014 13:18
Handheld DSC VHF vs. PLB for MOB SailFastTri Health, Safety & Related Gear 37 28-06-2014 19:42
Handheld VHF with GPS/DSC or Personal AIS? simonpickard Marine Electronics 14 13-12-2013 11:48
With Handheld VHF with DSC any need for fixed unit? simonpickard Marine Electronics 37 10-12-2013 16:56



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 18:17.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.