Can you offer comments to my proposed VHF setup?

[Pete7]

Originally Posted by rslifkin

I'd decently put an antenna on the mast for the longer range. A second antenna on the arch or a spreader would be a nice bonus, as having 2 VHFs is handy at times. And if it's on the arch, it'll still work if the mast or main antenna is damaged.

Same set up as ours. The plug and wire on the AIS arch antenna is long enough to reach the VHF set in the event of the masthead antenna failing whilst on passage. This did actually happen when we hit a tree with the masthead, don't ask

Pete

[j.g.evans]

I agree with the earlier comments regarding cable size. .5" or 11mm is definitely better. Get tinned cable because you don't want to take the mast down in a few years. The VHF signal should not interfere with the other wires. Any signal on the outside of the antenna connector will be connected to the mast via the mounting bracket. Anyway, this should not be a problem with a decent VHF antenna.

If you have not bought a VHF yet, then spend the money for one with built in AIS. Then you will not need a second antenna. You may not need radar either.

Another problem you will encounter is all the wires slapping inside the mast as the boat rocks at anchor. If your mast doesn't have a channel for the wires, then the following worked for me. Bundle all the wires together with heavy nylon ties spaced about 1' or 30 cm apart. Don't cut off the tails. Apply the tails so that the tails on adjacent ties are at 90 degrees. The tails will hold the wires in the center of the mast preventing slapping.

[rslifkin]

Originally Posted by Pete7

Same set up as ours. The plug and wire on the AIS arch antenna is long enough to reach the VHF set in the event of the masthead antenna failing whilst on passage. This did actually happen when we hit a tree with the masthead, don't ask

Pete

Good point on AIS. I wasn't even thinking of that. On a sailboat, I'd probably be inclined to put an antenna on each side of the arch in that case (1 for a second VHF, 1 for AIS) as I like having 2 working VHFs on board (ability to switch channels without losing situational awareness in a busy area or potentially missing something on the second channel due to dual watch taking over with 16).

[boat driver]

Originally Posted by mitiempo

The Tram 1603 is 38" in length.
https://www.amazon.ca/Tram-1603-Vhf-...10946671&psc=1

Also, with your vhf antenna on the stern arch the future Ais antenna should be on the masthead as they shouldn't be close together.

I disagree entirely-
VHF antenna on masthead so you get the efficiency of distance/height/power. This is 25watts transmitting line of sight.
AIS , particularly B in 2 or 5 watt is better on arch provided it is 10 feet atw.
this is because the signal is weak as is- and the short coax run will increase the reception- as well being so low powered the loss of signal will be less on the shorter coax. It is line of sight also, but does not have the power to broadest more than 3-5 miles consistently.
VHF antenna as far apart ideally, but 6 feet is the general rule- AIS and VHF radio.
The other way is install the AIS vertically upside down,with the VHF masthead- but this again leads to likely signal blockage on the mast side. works well with spreader equipped AIS?VHF antenna.

[mitiempo]

Originally Posted by boat driver

I disagree entirely-
VHF antenna on masthead so you get the efficiency of distance/height/power. This is 25watts transmitting line of sight.
AIS , particularly B in 2 or 5 watt is better on arch provided it is 10 feet atw.
this is because the signal is weak as is- and the short coax run will increase the reception- as well being so low powered the loss of signal will be less on the shorter coax. It is line of sight also, but does not have the power to broadest more than 3-5 miles consistently.
VHF antenna as far apart ideally, but 6 feet is the general rule- AIS and VHF radio.
The other way is install the AIS vertically upside down,with the VHF masthead- but this again leads to likely signal blockage on the mast side. works well with spreader equipped AIS?VHF antenna.

You're not disagreeing with me - it was the op who stated that he was going to put the vhf antenna on the arch.

You are right, best place for vhf is the masthead. AIS either on the arch or sharing the masthead antenna with a good splitter like the Vesper.

[KP44]

Originally Posted by mitiempo

You are right, best place for vhf is the masthead. AIS either on the arch or sharing the masthead antenna with a good splitter like the Vesper.

VHF antenna with marine RG-213 at the mast top. The one time you might NEED long range will pay for doing this right. The rest of the time you will have clear, clean communications.

[KP44]

Originally Posted by Pedro -Dawn-

Hello All!

I can’t seem to pass page 8 of the VHF threads. Not sure if this is a problem with the forum settings, etc. I am currently refitting a 35ft monohull with a 40ft mast.

4 - possibility to running another 2 separate cable runs for (i) a dedicated AIS antenna in the future; and (ii) a higher gain antenna - so I could have a broader bandwidth antenna for regular usage and the possibility to switch to a higher gain if needed.
Pedro @dawnexpedition

The gain in decibels for an antenna does not describe a gain in power. It indicates the direction the antenna radiates power. A 3 db antenna radiates more power horizontally and works well on a sailboat because the horizontal "beam" is wide.
A higher db antenna has a narrower horizontal beam. When heeled, you might transmit towards the water and the sky. When standing you might lose signals from handhelds and powerboats (low antenna) right next to you because a high gain antenna is focused towards the horizon.
Using good 50 ohm low-loss cable like RG-213 keeps your power high and is better than a high-gain antenna.
Radios automatically reduce their power (to keep from burning out) when we use lower grade, lossy cable that create a standing wave in the cable. Going to "high power" does not help because the radio protects itself. So always use the best cable.

[Pedro -Dawn-]

Originally Posted by mitiempo

The Tram 1603 is 38" in length.
https://www.amazon.ca/Tram-1603-Vhf-...10946671&psc=1

Also, with your vhf antenna on the stern arch the future Ais antenna should be on the masthead as they shouldn't be close together.

You are right! The Amazon picture was very misleading. Had to be returned, since it can't fit in a travel bag, at least without bending it. Not sure if this is a problem or not.

[Pedro -Dawn-]

Originally Posted by IOM

Being at the top of the mast will always be better for range
If you running a raspberry pi, and powering it with a switch mode supply, then be warned the noise from the supply can be so bad it can destroy even a wifi system on the boat. I changed to a linear supply , which is less efficient, and created more heat, but a lot less RFI. Alternatively spend a lot of time on RFI suppression and screening on the Supply.

Thanks for the info!! To be honest, I didn't understand much hehehe. I will power the raspberry pi with a dc-dc converter to 5 volts.

Or are referring to the power to the wind instrument?

Thanks!!!