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Old 21-02-2016, 17:35   #1
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Question Need an insulated split backstay - synthetic rigging vs. wire insulators

I'm replacing the rigging on our Aloha 34, and while I'm at it I'd like to insulate the split backstay for our Icom-M802 radio. Ive just priced everything out and the material cost for wire, multiple sta-lock wire end fittings, 2 insulators, triangle plate, turnbuckles, etc is at $930 for the backstay alone. This is more than expected, but acceptable if its our best option.

For fun I went ahead and priced a split backstay made of 9mm dynex dux on the upper and 7mm dynex dux on the lower sections of the split with all the appropriate end fittings and tensioners. The synthetic split backstay is actually cheaper, coming to about $760. Im assuming I could then just run a copper wire up the synthetic backstay and not worry about insulators.

Is there anything wrong with using synthetic standing rigging only on the backstay, but 316 wire on the forestay and shrouds?

Ongoing costs would probably be higher with the synthetic since it has a 5-8 year replacement interval, while wire seems to be 8-10+. The raw synthetic rope section to be replaced currently costs $350 while the wire replacement cost is $140 (assuming the sta-lock fittings can be reused and the insulators dont need to be replaced).

Do you think the lower upfront cost and benefits of a synthetic split backstay are worth the higher replacement costs and any potential drawbacks synthetic might have when compared to an insulated wire split backstay?
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Old 21-02-2016, 18:10   #2
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Re: Need an insulated split backstay - synthetic rigging vs. wire insulators

Are you planning a long passage far from shore such that you need SSB? If you are planning several week long passages maybe you can make do with a satellite phone.

Why do you need to replace the entire backstay rigging? Maybe you could just replace the upper single wire section with an insulated section. I'm not understanding why you have to replace the 3-way plate and lower wires. If they are already beyond replacement age then that doesn't really affect the decision to replace I guess. If you go with stainless wire, stand the high voltage wire off from the lower wire rope with UV resistant plastic pipe until it gets past the first insulator in the upper single section. But if the lower chain plates are insulated and not bonded to the rest of the boat you only need one insulator at the top and you can attach the tuner wire to either one of the lower wires.

If you go with synthetic I would recommend not running the wire inside the synthetic rope. That can degrade the strength of the rope. I would just gently run the high voltage wire parallel to the outside of the rope using some UV resistant clamps. I would not make the clamps really tight as this might cause undo stress in the synthetic.

You could also consider an antenna raised on a halyard only when you need to use it.
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Old 21-02-2016, 18:49   #3
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Re: Need an insulated split backstay - synthetic rigging vs. wire insulators

We're pretty set on using the HF radio and some sort of insulated backstay. We already have our HAM licenses and the equipment...just need to get it installed.

The standing rigging on our boat is of unknown age and origin. Based on owner history, location, and tidbits of information from the PO (who wasn't sure how old the rigging was - it was replaced by a previous-PO) I could guarantee its at least 10 years old. I wouldn't be surprised if it were 15-20 years old. Everything is swaged, some of which have vertical cracks in them. The clevis pins are undersized for the chainplates' pin holes, yet a larger pin won't fit in the turnbuckle (probably undersized) toggles. I'd feel alot better about it if we had a clean start with the rigging, and this was factored in at purchase anyways.

It seems to me that if there was ever a good candidate for sythetic rigging beyond just for performance racers who dont want the wire weight aloft...itd be for someone wanting an insulated split backstay. The multiple insulators and terminals needed for wire makes synthetic look like a very attractive option.

I'm definately a newbie though, so I want to make sure a synthetic backstay isn't a bad idea! Would the synthetic line stretch and differential thermal expansion between it and the mast make me hate my life with endless tuning, or is that not such a big deal?
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Old 21-02-2016, 23:00   #4
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Re: Need an insulated split backstay - synthetic rigging vs. wire insulators

Give Chicago Yacht Rigging a call and see if they have 'Alpha Ropes D Core XTM 78' in the right size. It's a very good substitute for Dux but at about 1/3 the price.
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Old 21-02-2016, 23:11   #5
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Re: Need an insulated split backstay - synthetic rigging vs. wire insulators

Sent you a PM as I have a backstay with Norseman insulator for sale...You may wish to do an entire professional inspection of all rigging and chainplates and maybe replace or at least polish and rebed....
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Old 22-02-2016, 02:44   #6
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Re: Need an insulated split backstay - synthetic rigging vs. wire insulators

I don't think the decision to use synthetic should be based on the SSB antenna. Decide the type of back stay you want first. There are ways to address the antenna no matter which back stay technology you choose. Talk to a rigger knowledgeable about synthetic or give Coligo a call and ask them about your particular situation.
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Old 22-02-2016, 07:47   #7
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Re: Need an insulated split backstay - synthetic rigging vs. wire insulators

Quote:
Originally Posted by transmitterdan View Post
I don't think the decision to use synthetic should be based on the SSB antenna. Decide the type of back stay you want first. There are ways to address the antenna no matter which back stay technology you choose. Talk to a rigger knowledgeable about synthetic or give Coligo a call and ask them about your particular situation.

Plus 1

There is no cost saving only weight aloft. On our HF setup I used a premade wire to rope halyard for our longwire with a length of Dynema spliced to the wire for the deck termination. Ideally you want a direct line from long wire to tuner to ground plane with the tuner to ground plane run as short as possible. Keeping it away from other rigging to reduce the possibility of coupling. Sounds like you need to spend a bit of time on the rig before you mess with the radio setup.
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Old 22-02-2016, 07:59   #8
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Re: Need an insulated split backstay - synthetic rigging vs. wire insulators

You really only need one insulator in the backstay (at the top) assuming your backstay isn't grounded. Some worrywarts will talk about RFI burns but split plastic covers will address that. I know someone who did multiple trips to Bermuda with SSB with no difficulty with this setup. If you happen to have 9/32
rigging I have an unused insulator I'll part with at small cost--Maine50
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Old 22-02-2016, 09:20   #9
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Re: Need an insulated split backstay - synthetic rigging vs. wire insulators

I second Maine50's input about the single top insulator for fiberglass vessels but I also recommend just running a separate long wire antenna and forgetting about firing up the back stay altogether. This way you can play around with different antenna lengths and feed points for instance if you want to try a center fed diapole etc. in the future. Insulators are costly and points of potential failure.

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Old 22-02-2016, 09:25   #10
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Re: Need an insulated split backstay - synthetic rigging vs. wire insulators

A turning BLOCK on the top of the mast and a rope halard to a lenght of life line with swage ends

The best antenna you can have and you can raise and lower at your will. Cheap and works like a champ.

Just clamp the GTO15 to the swage.

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Old 22-02-2016, 11:58   #11
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Re: Need an insulated split backstay - synthetic rigging vs. wire insulators

My solution is to hang a pulley at the masthead and run a line through it with a copper wire on the up side. The rope lead can either go to the mast foot or aft. Rig it to the quaters or stern arch to get clear of the back stay. You don't need to buy a commercial rope aerial just take a length of 14g wire and weave it in and out of the line using a fid, (I tried zip ties - worked but the UV destroys them in about 2 seasons) takes a while because of the length but easy to do. Then solder a standard radio plug on the end or solder directly to the insulated feed (minimizes connector noise, coupling noise can, I think be a problem for backstay aerials). It is best done with a braided line and actually cheaper line tends to be easier as the weave is not so tight. I have tried to thread a tubular line, which is how the commercial ones are done, but proved impossible, The gain is that you then have an aerial that is independent of the rigging and very easy to lower if you need to. Also means that if you do loose the mast you can rig the aerial across the deck for emergency transmission. Performance is at least as good as a back stay (copper is a more efficient conductor than S/S) but cost is minimal and you don't have to introduce insulators to the back stay.
I use a conventional underwater groundplane but I have heard of using the guard wire as the ground plane forming a 'L' dipole, not tried it but would be an interesting experiment. I have wondered if a rope backstay might improve reception by removing a conductor which is potentially paralleling the aerial although I think the difference would be marginal unless on a steel boat or one with a grounded rig (lightening path?) mine isn't as I have a wooden boat with internal chain plates. Anyway so far reception has only been limited by propagation condition so good enough for me and I am as clear on Tx as Rx.
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Old 22-02-2016, 12:29   #12
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Re: Need an insulated split backstay - synthetic rigging vs. wire insulators

Single insulator probably won't work because it's a split backstay with unknown electrical conductivity at the split. Could cause fits for the antenna tuner. If if it was a single backstay, that would be the way to go.

You can do a standoff wire insulated from the back stay with short pieces of PVC pipe and zip ties which would be the cheapest way to go. Cuts out the Norseman/StaLok wire insulators which are probably half or more of your backstay estimated cost. Got lucky on mine and picked up the insulators on Ebay cheap. On our last boat used ceramic insulators like the ones used by the power company on their power pole guy wires. Looped the wire around the insulator and secured with Nicopress sleeves. Worked fine for the 10 years we owned the boat.
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Old 22-02-2016, 18:17   #13
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Re: Need an insulated split backstay - synthetic rigging vs. wire insulators

Hi redpointartist,

I went through the process several years ago and couldn't justify the cost and the possibility of failure due to lightning strike (yes I have been hit before). I ended up simply attaching an insulated wire (looks like lifeline wire) with swaged loops both ends to the mast head and attaching at the stern convenient to the tuner. Cost about $50 all assembled. I bought it from a cruiser in Sint Maarten who was trying making a few $. Would be cheaper doing it yourself. There is a lot of bull#### about HF antennas, RF danger etc etc but do yourself a favour and research it yourself before you commit to the very considerable expense of insulators etc. I also bought a KISS groundplane see KISS-SSB TM to avoid installing a groundplate and hole in the hull (another lighting risk) . The whole system works very well.

regards

Andrew
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Old 23-02-2016, 06:16   #14
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Re: Need an insulated split backstay - synthetic rigging vs. wire insulators

Lightning is no more or less likely to break a backstay with or without an insulator. Stories of lightning breaking an insulator are an old wives tale I suspect.

Your lightning "theory" actually increases the chance of hull damage due to lightning. If there is no direct path to the water (e.g. keel or hrough hull) then lightning might take a path directly through the hull. Its a good idea to make it easy for lightning to get out of the boat.

You are right, there is a lot of nonsense circulating about HF radio theory.
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