Weak VHF

[hellosailor]

"A sailboat with 8' off the water?"
Not unusual when a six-foot tall sailor is standing in the cockpit of a sub-40-footer with a handheld. Because not all of us want ram-mics and sometimes having a lower power radio on deck, beats working with the one below.

You know what happens if you hail the USCG on channel 16 in any busy location? If you're not on fire or sinking, the next question they'll ask is "Do you have a cell phone? Please call us directly at...." because they want the channel clear. Now, an antenna for that is even more problematic, since the losses per foot of cable are so much higher.

[Laidback]

Originally Posted by frelin

The antenna is this one SHAKESPEARE 5216 15" BLACK LIGHT WEIGHT SAILBOAT ANTENNA - Shakespeare Marine VHF Antennas - Shakespeare Marine VHF Antennas - Shakespeare Antennas

Frelin,
Ignor the comments about your antenna, it was not designed for long range VHF transmission. It is designed for a purpose, as a race boat antenna, for example : for race officials to communicate with those racing.
It would work better if mounted at mast head, however its db gain does not provide range.
Shakespeare's antennas are highly regarded throughout the world, not only for VHF but also for HF.
If you wanted to improve tranmission then your best is to invest in an antenna that is designed for long distance (although generally 35nm would be max range - if conditions were good)
Shakespeare does have such antennas - producing 6db gain IF they are mounted as high as possible. Preferable on the top of the mast. While it is also desirable to use RG 8 coax to connect the antenna to the radio, RG 58 can be used, one method of bringing it down from the mast head (instead of inside mast) is to lead it first to the aft side of a spreader- tape it - then bring it down to deck gland near the radio and connect it.

[AnchorageGuy]

Originally Posted by frelin

Ok, but It's a real hazzel to step the mast down.... So agian, how big difference will a better antenna make mounted in mast top or mounted on railing?

Also, how big does it have to be? I'm flying down to guatemala so if it can fit in a bag I would be happy. Othervise I could buy it down htere somewhere.

You keep saying it is such a hassle to take down the mast, but there is no need to take down the mast to install an antenna. WG

[hellosailor]

"but there is no need to take down the mast to install an antenna."
Very true, but depending on your ingenuity and internal options for installing the cable properly secured, it may be best to take down the mast.

[Sailndive345]

Just curious... Wouldn't it be easier to run the cable with the mast 'up' with the help of gravity? If there are messenger lines available, it ought to be rather simple. If no messenger lines, a horizontal (unstepped) mast is a real pain to run cables through...

Sailndive

[hellosailor]

If you're running the cable "up" the mast, how do you secure the cable TO the mast, every couple of feet, to prevent the cable's own weight from stretching it as it hangs loose from the top? Not just stopping "slap", but securing it against it's own weight, which will stretch the cable, compress the insulation, and change the electrical properties of it as it ages?

[Sailndive345]

Originally Posted by hellosailor

If you're running the cable "up" the mast, how do you secure the cable TO the mast, every couple of feet, to prevent the cable's own weight from stretching it as it hangs loose from the top? Not just stopping "slap", but securing it against it's own weight, which will stretch the cable, compress the insulation, and change the electrical properties of it as it ages?

Well, since the OP said it was real hassle to unstep the mast, I visualized a fairly tall, probably keel stepped mast. These masts generally come equipped with a cable conduit (w/ messenger lines) just to avoid the type of issue you mentioned. I also envisioned the cable being fed from the top of the mast as another poster suggested (with the PL259 connector already soldered.)

Possible that I am way off base - wouldn't be the first time

Sailndive

[fairbank56]

Iv'e wired many masts and it's generally easier with the mast on the ground but not necessarily so. When it's on the ground, we use a fish tape to run through the mast/conduit to pull cables in or if there are already cables in the mast and you just want to add/replace a cable, we use one of the existing cables. Pull it out with leader attached, pull back in with new cable/s. Hopefully you have an internal conduit but it may be difficult to tell with the mast already in the boat. Sometimes the conduit is fitted into an internal track in the mast and sometimes it's attached with rivets or screws. Is there a light already at the top of the mast? If so, you can pull that wire out from the top with a leader attached and then pull both lighting wiring and coax back in at the same time. You don't need to worry about securing the wiring except at the top where it exits the mast. While there may be a small finite amount of stretching over time, it's not going to make any significant difference. If there is no existing wiring to work with you can just drop a weighted line down from the top and have someone fish it out at the bottom exit hole with a stiff wire with a hook in the end. Getting it into a conduit, if there is one, may be very difficult in this situation as the top of the conduit may be some distance down from the exit hole. Much easier on the ground in this case. Your also going to need to drill and tap holes at the top for the antenna mount and cable clamp. All this may be a little much for someone with no experience doing mast wiring but it is definitely worth it as far as performance goes for a VHF antenna to be at the top of the mast vice on the rail.

Eric

[delmarrey]

Originally Posted by fairbank56

Iv'e wired many masts and it's generally easier with the mast on the ground but not necessarily so. When it's on the ground, we use a fish tape to run through the mast/conduit to pull cables in or if there are already cables in the mast and you just want to add/replace a cable, we use one of the existing cables.
Pull it out with leader attached, pull back in with new cable/s. Hopefully you have an internal conduit but it may be difficult to tell with the mast already in the boat. Sometimes the conduit is fitted into an internal track in the mast and sometimes it's attached with rivets or screws. Is there a light already at the top of the mast? If so, you can pull that wire out from the top with a leader attached and then pull both lighting wiring and coax back in at the same time. You don't need to worry about securing the wiring except at the top where it exits the mast.
While there may be a small finite amount of stretching over time, it's not going to make any significant difference. If there is no existing wiring to work with you can just drop a weighted line down from the top and have someone fish it out at the bottom exit hole with a stiff wire with a hook in the end. Getting it into a conduit, if there is one, may be very difficult in this situation as the top of the conduit may be some distance down from the exit hole. Much easier on the ground in this case.
Your also going to need to drill and tap holes at the top for the antenna mount and cable clamp. All this may be a little much for someone with no experience doing mast wiring but it is definitely worth it as far as performance goes for a VHF antenna to be at the top of the mast vice on the rail.

Eric

Easier said then done. Most masts have mid-mast running lights and sometimes spreader lights or radar. Which have to be spiced in/out to run wiring. Larger masts generally do have an internal conduit. On my Z-spar small sections had to hole-sawed thru the front to the back and into the conduit to allow for these extra lights/wires. Then I had to add a support tube to cross over from front to back to keep the internal halyards from taking out the wiring.

[AnchorageGuy]

Wow guys, lets not scare the poor fellow. I have done probably a thousand coax installations or replacements on sailboats over a lot of years and never had an issue running the cable. That was always the easy part. In only two cases did the mast have to come down and one instance where it was already down and we convinced the owner to replace all of the wiring and cable since it was getting up in years. If someone is inexperienced and not comfortable working at the masthead in a chair, it is still a whole lot less expensive and time consuming to hire a qualified and experienced installer to do it than pulling the rig. But again, this is just my opinion and we know what they are like WG

[Boracay]

VHF's are so cheap these days why not also replace the transceiver. I've seen some new basic good brand name ones for under $US100. They are small and would not be a problem to carry out of their box.

I'd also suggest putting it close to the cockpit so it can be used while underway and enabling the DSC if at all possible.

We obsess over liferafts, but it's possible that more lives have been saved by VHF radios.

[frelin]

Thank you ALL for great answers.
The mast is deck stepped, but I've never been taking a mast down before... Therefore, it would be best if I didn't have to. Altough, if I have to I might as well change all the other wires in there, since there pretty old.

fairbank56 talked about pulling wires and that made me remember that I used to have an old antenna for the radiocompass. I removed that antenna but I thing the cable is still up there. I'm not sure if it's possible to pull it, but defently something to look into when I go back...

Somebody said, go and buy new VHF unit straight away, advisable?

cheers

[Sailndive345]

Originally Posted by frelin

Thank you ALL for great answers.
The mast is deck stepped, but I've never been taking a mast down before... Therefore, it would be best if I didn't have to. Altough, if I have to I might as well change all the other wires in there, since there pretty old.

fairbank56 talked about pulling wires and that made me remember that I used to have an old antenna for the radiocompass. I removed that antenna but I thing the cable is still up there. I'm not sure if it's possible to pull it, but defently something to look into when I go back...

Somebody said, go and buy new VHF unit straight away, advisable?

cheers

If the in-mast wires are so aged, it is likely that your standing rigging is quite tired as well... If you unstep the mast, it may be a good opportunity to replace whatever else needs replacing for your piece of mind

Sailndive

[hellosailor]

If the old VHF is working, a new one won't work any better. It may do more (AIS, distinctive calling, tri-watch) but the plain old radio functionality won't be any different. So there's no hurry to replace the radio. If you do, clean up the old one and put it in a Tupperware with some dessicant, you'll have a spare.

Sailndive makes a good point about replacing the standing rigging, if it is 20 years old just replace the rigging and all stainless fittings without thinking twice. If the budget allows. 10-15 years, something to think about. 15-20 years, time to give it real serious consideration.

[s/v Jedi]

The thing with old electronics is that the capacitors go bad (they age). So, at some point it starts making sense to replace it before it breaks down. Determining that point is tricky as expensive radios should have better quality components and last longer but I would definitely replace a 15 year old VHF because the replacement doesn't cost too much anyway.

cheers,
Nick.