Fitting a VHF aerial and cable

[ecb]

Going to hopefully fit a VHF aerial and cable to the mast next month. The boat is 22ft, with alu mast in tabernacle. Mast is removed from boat each winter.

Any tips on the type of aerial to use? More importantly, how best to run the cable into and down the mast to avoid snags with halyards and chafe?

Been relying on a handheld up till now, so since I might venture a bit further afield this year, I thought I should do a proper installation.

Any advice and wisdom most welcome!

 

[cindersailor]

A piece of advice I followed when running internal cables down the mast to avoid them slapping around inside with the motion of the boat was to add a cable tie every couple of foot and leave the tail attached. If these are arranged so that each one points in a different direction it should help keep the cable away from the mast wall. This has worked well for me, although I cannot comment on whether this would interfere with internal halyards as mine are all external. Newer masts will have an internal cable conduit which can be used to avoid this problem

If you have your mast down running the cable through should not be too much of a problem, particularly if you can remove the mast foot to gain access inside. A thin line (whipping twine is sufficient for a VHF cable) with a weight small enough to pass through your upper cable hole in the mast will allow you to get a line down the inside with a bit of lifting and shaking. This can then be used to pull your cable through to the bottom of the mast. If you want to add the cable ties you will need to introduce the cable from the bottom assuming you can get to foot off.

 

[philip_stevens]

Euen,
my boat is at Gaffers & Luggers, so we are not too far apart.

If your mast has a slot or hole at the back (or the side) of the top of the mast, either or one side of the sheeve, it may well have a dedicated "way" down to the bottom of the mast. First off, have a look to see if there is a slot or hole at the top. If there is, and also an outlet or hole at the bottom, that is the way for your aerial cable.

If you are going to remove the mast at lay-up, you will have to get a waterproof co-ax connector to fit on the deck beside the tabernacle. This way, you can disconnect the coa-ax when you remove the mast. An alternative is to get a watertight gland on the deck and connect/disconnect below deck with a male and a female co-ax connectors.

regards,
Philip

www.stiveswebdesign.co.uk

 

[steve28]

When you put the cable through the deckhead use a cable gland do not cut the cable abd put a plug and socket.

The glands you can get have three screws to release the top section this will enable you to pull the cable through to remove the mast.

 

[bruce]

buy GOOD coax, this is a long run and power loss will be greater with light weight coax...

 

[Salty John]

Hi ecb,
I agree with bruce, buy good coax. Most lower quality antennas come with small diameter RG58 already attached, usually with a crimped connection. A long run of RG58 can cost you 20 miles or so in range. Use RG-8 mini if you can. Of course it will be 50 ohm cable, TV coax is 75 ohm and not suitable for vhf use. Celmar make a good antenna, CELmar0-1 I think it is called. Another is the Metz Manta-6, all stainless, light, lifetime warranty on the coil and used exclusively by the US Coastguard for search and rescue vessels.
Good luck.

 

[Hardley]

If your mast is down, attach whipping twain to main halyard or topping lift, at foot of mast, pull up to top of mast, with a piece of wire through your drilled hole you can hook the twain through, attach to cable and pull it down.
If possible I would take cable to VHF without cutting, might be a bit of a fiddle when you want to get the mast down, but would give the best connection.

 

[wicked]

On my 26 footer I changed from a stainless whip to a stumpy aeriel from Silva. Worst thing I ever did - complete rubbish!. Changing back to a stainless whip this season.

Dave.

 

[William_H]

Just to be contraversial my tables show a typical RG58 coax giving 1.6 decibels of loss in 10 metre run. That represents a fairly small loss of transmitted power perhaps 5% which represents a loss of performance that would be barely perceptable compared to RG8 cable. (Certainly not a loss of 20 miles range) There is no doubt that a masthead mast will give you better performance however if you become dismasted the antenna is not much use to you. Especially if it is difficult to get the cabler up the mast you should consider an aft deck mounted antenna on a short pole.
PM me for details on how to make an effective antenna for this role either as a main or standby antenna. regards will

 

[Anthony]

I am led to believe that RG58 is not designed for external use, hence prone to degredation by UV and water etc, can anyone comfirm this or suggest a suitable alternative?

Anthony

 

[fireball]

But if it is run up inside the mast then there is very little that will be exposed - so it will be indoor use!