# Wiring my boat for cable TV



## Perithead (Nov 16, 2007)

Last weekend I installed a flat screen TV in the saloon of my sailboat so that my girlfriend can have something to watch while she is bored on the boat. There isnt cable wired through the boat so I am going to have to do it myself. 

My marina has cable hookups beside the shorepower hookups. I was wondering if there was a special cable or anything like that that I need in order to get it working.

Also, how should I connect it to my boat. Do they make some sort of plug-in to go on my boat simular to a shore power hookup?


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## btrayfors (Aug 25, 2006)

Had the same problem a few years ago.

You can find what you need at the local Radio Shack, or online. Here's a sample of a very good quality cable with the connectors on each end: Belden #9104 75 Ohm CATV Cable 100' TNC Connectors - eBay (item 200207361675 end time Apr-11-08 10:59:17 PDT)

You probably won't need 100' of cable, depending on the distance to your shore connection.

You'll want to purchase or make up two cables: one for reaching from the cockpit to the dock, and one for running underdecks to the salon.

I installed a CATV receptacle in the cockpit, and ran the cable below decks all the way to the salon.

To keep rain/spray out when not in use, I installed a 90-degree fitting on the receptacle in the cockpit, pointing down.

Works like a charm!

Bill


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## dflyin1 (Mar 12, 2006)

I am a cable guy in Tennessee. You shouldn't need anything you can't find at radioshack. As long as you get the barrel connectors tight you shouldn't get any water in the cable line. Just don't get them much over finger tight. Thats bad too. One thing I am considering so that I don't have to rewire my boat is this. Now mind you I haven't tried it yet but will soon. 

I am rerunning my vhf with RG6 which is the current in house standard wiring. 
The vhf wiring I have currently is rg58 which is similar in nature to what was used 15 yrs ago in houses. what I did was buy Rg6 to Rg58 connectors for a buck or so each. In your case you could potentially piggy back off of your vhf antennae wire simply by cutting the line at your nav station replacing it with a standard cable end Try to get one from a cable guy or get the good ones at lowes.(no twist ons). Place the RG6 end connector on the other end going to the vhf and you will be able to swap between cable and vhf when not in port. 

Now for the outside, somewhere near the mast should be a coupling going from cabin to mast. Cut the end off of it and replace it with rg6 to Rg58 coupler and you should be done. Then all you have to do is when coming into port undo coupling and replace with cable line going to shore. One other benefit I can see is that you could potentially use your vhf antenna as a tv antennae when cable is not available.


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## sifucarl (Jan 26, 2008)

Dfly has good info. I used to install Dish Network systems. If I had the opportunity I'd replace all the cable to ensure there are as few connections as possible. A large part of the problems we encountered were water intrusion issues, I can definitely see this on a sailboat. Additionally, I'd opt to use a compression style connector vice a crimp style, they are better resistant to water intrusion. Hell for a few pennies more you can get compression fittings with rubber o-rings.

Here's a quick how to. How Do I...Install Coax Connectors - HomeTech Solutions

If you do replace all cable, go with all RG-6, costs a bit more but it can handle higher frequencies than RG-58 cable. If you ever decide to get satellite service you won't have to worry about it.

Too bad I'm not down south or I'd come out and help out.


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## sailingdog (Mar 19, 2006)

Since you're setting this up for a relatively permanent installation, you should probably install an external cable-tv inlet, like the shore power inlet on the boat.










I would use marine-grade coax cable and compression fittings, which are fairly easy to install.

Also, I'd recommend installing an coax outlet in the boat, rather than just running it to the back of the TV, since, that will make replacing the connection between the boat and the TV much easier to maintain. The cable attached to the TV may get damaged and such... and if you ran it directly into the TV, you'd have to re-run the cable more likely than not in the case of damage.

*I would highly recommend people not do what DFLYIN1 has suggested. * Having couplers in the VHF antenna line will attenuate and weaken your VHF radio's signal. *IMHO, the VHF is an important piece of SAFETY GEAR, and shouldn't be tampered with just for entertainment purposes.* Also, IIRC, the VHF antenna is tuned for the wrong frequency range for ATSC over-the-air HDTV signals.


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## TSOJOURNER (Dec 16, 1999)

I installed the fitting that SD shows above. Much better that running a cable through a porthole or other opening, particularly when it rains. I use a marine grade cable from the dock to the fitting and a Radio Shack cable permanently connected from the back of the fitting to the tv.


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## SVAuspicious (Oct 31, 2006)

There is a more important reason for keeping your VHF and TV transmission cables separate. The characteristic impedance of the cable for your VHF is 50 ohms (RG-58, RG-8, RG-213, etc). The characteristic impedance of the cable for your TV system is 75 ohms (RG-59, RG-6, etc). Do not mix them. It's tough on the equipment and reduces the effectiveness of ... well ... everything.


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## dflyin1 (Mar 12, 2006)

I wanted to do a little research before I replied regarding the 50 vs 75 ohm impedence issue, The atached quote should suffice.

Q. I thought RG6-U coax was not as good nor compatible to use as antenna cable for scanners. Is it also a good choice for transmitters in the 158.00MHz range? Thank you, Jim

A. This common misconception originated in the early days of scanner listening. Many misguided folks use long lengths of lossy RG-58/U coax for scanner reception (and VHF transmission) just because it has a 50 ohm impedance, convinced that coax of any other impedance simply won't work. The fact is that while a proper impedance match is desirable to avoid resistive losses through the inner dielectric (insulation) from high voltages which develop during a mismatch, very few antenna systems exactly match 50 ohms anyway, especially over wide frequency excursions. Although RG-6/U is 70 ohms, not 50 ohms, its low-loss characters tics more than make up for any theoretical impedance mismatch. If you substitute 100 feet of RG-6/U for RG-58/U in scanner monitoring above 30 MHz, I can guarantee you better reception, and the higher in frequency, the more the improvement. I use RG-6/U exclusively for my VHF/UHF monitoring, and use RG-58/U only for shortwave where its losses are not that severe. Coaxial cable, by its very construction, is virtually immune to outside electrical interference. The best shielded coax is always the better choice, and RG-6/U is very well shielded. It also has less loss in its dielectric (inner insulation) than competitive cable types. So that's the long answer which could have been shorter--"Yes!" Coax can be run underground, through water, alongside power cables, near satellite dishes and other electronics equipment without picking up interference. Try to keep it as short as possible, however, to avoid resistive losses from the longer lengths.

This link is for radios in addition to vhf marine, I must say though that I have about 3 yrs of telecommunications and radio training regarding vhf signals SNR SWR, The only point I was making was that it is possible to use Rg6 without problems. I contacted Uniden who makes Vhf marine radios and they recommended Rg59 which is an inferior grade of coax used 20 yrs ago in homes. The benefits it has makes up for any propagation loss.


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## sailingdog (Mar 19, 2006)

Dflyin1-

When quoting a source...it would give the quote a lot more credibility if you say who you're quoting and include a link.


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## sifucarl (Jan 26, 2008)

dflyin1 said:


> "Yes!" Coax can be run underground, through water, alongside power cables, near satellite dishes and other electronics equipment without picking up interference. Try to keep it as short as possible, however, to avoid resistive losses from the longer lengths.


Just keep in mind, all Coax is not created equal. RG-6, as others, come in different configurations. Shielding (dual, quad) will make a difference in its ability to fend off interference, as well as if the system is properly grounded.

Not all coax is water resistant, underground/underwater grade cable will have a silicone barrier to prevent water intrusion because water will still leach through the plastic outer covering. Connectors should never be underground or water, they are not watertight, no matter how good your fittings are. They do however sell a sealant if you have to splice a cable (I'd still opt to replace the entire length if you can afford it). Its made of a sticky substance, not unlike what you find in one of those sticky mouse traps, and it folds over the splice area to give it greater water resistance, but its meant to be temporary.


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## dflyin1 (Mar 12, 2006)

I apologize if I was unclear. My previous post included a quote. You are absolutely correct that you can have absolutely no splice underwater. infact it isn't even good to have one at all if you can help it. We use snott blocks (gelsplices) to minimize exposure but moisture still can get in.

My whole point was that it is possible and not harmful to use rg6 in the above application.


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## sifucarl (Jan 26, 2008)

> My whole point was that it is possible and not harmful to use rg6 in the above application.


Well said and I agree.


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