Radar connection, chocblock good enough?

I too had to dismast every year and that involved undoing a chocolate box hidden behind the headlining. Each year I was amazed that the radar worked first time as the wires became more and more shredded each year. Rewiring the radar became the job that I hated most about boat ownership! However, the chocolate box (which was inside a Raymarine connection box) never showed any signs of corrosion or decay.

Eventually, I purchased an Index waterproof deck plug at phenomenal expense and had the two sections soldered professionally (at even more phenomenal expense). That year our plans changed and we moved the boat to Brittany where we didn't need to drop the mast (even when I lost the main halyard it was re-reeved by a Frenchman on a crane).
Then we sold the boat! However, there was absolutely no sign of corrosion or water ingress in the new deck plug.

My recommendation is to go for a properly made up deck plug.
 
JayBee said:


OK. Here's the Index Marine description of the choc block I use:

"A range of high quality 12 way connector strips. Each strip has nickel plated brass screws and inserts plus stainless steel cable leaf protection for better connections."

http://www.indexmarine.co.uk/connector.html

What magic metal are busbars and their screws usually made from?
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Don;t care what it's made of., It's choc block. Therefore I hate it. Doesn't have to be logical or reasonable, I just do :)

To be serious, those do look rather better than the average choc block I will admit - the only niggling issue in my mind would be the thread size on the terminal screws. Bus bar would have bigger and therefore less likely to strip threads
 
I put my radar on a post, partly to avoid the hassel of diconnecting it every time I took the mast down. I could have left the cable intact but very unwisely I cut it to make it easier to remove the post.

I connected the fine data cables by soldering them into a computer type multipin connector. The power cables were too thick for that but a chock block was OK for those wires. The real problem is the very fine coax cable. I bought a small coax connector but the inner coax cable was just too fagile to take the strain of this connector. In the end I just used the inner parts of the connector and covered it in heat shrink cable then reformed the outer wire mesh and covered that in thicker heat shrink. It is more of a performance than just using a chock block for everthing but I had no confidence the fine cables would stand up to repeated clamping in a chock block.
 
Brigantia said:
Yes!

'Cos there is no such thing as "top quality choc block". There's cheap chocblock and expensive chocblock and they're all carp chocblock!

Even setting aside the perenial problems of rusted up screws, I've lost count of the number of times I've tried to undo choc block connections only to find that the screw has stripped the threads of the block or fallen out completely or otherwise ceased to make a good connection.

But to be fair, below decks inside a terminal box protected from damp it's likely to be adequate for the purpose - I'd personally spend a few pennies more on a proper bit of busbar but then I'm somewhat of a perfectionist when it comes to electricals (it's the way I was taught, only the best was just about good enough and even then only just)
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I don't understand the use of 'busbar' for connecting a multiple cables.....can you give me a link for the type you would recommend please? I'm sure that I've got the wrong terminology as i thought 'busbar' meant a strip with multiple connections all connected as one !
 
Quality tinned copper crimp terminals, crimped on with a proper ratchet crimper, with eyes going to a terminal strip with shake proof washers.
If space does not permit, bullets male and female, or cord ends into Index marine type choc block as already suggested.
Plain wires going into choc block should be avoided. The Index marine stuff has a leaf which is better.
Heatshrink and glue type butt connectors are good for a more permanent install and do not require a junction box as the above methods do.
 
samwise said:
What size connectors did you buy?
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I didn't buy them, I was given them by a Furuno technician. They were two different sizes, colour coded red and blue, so they may be the same size as those on the Cablecraft pdf, which I linked to earlier. I notice that Cablecraft sell them in packs of 500, but they are available elsewhere in smaller quantities - perhaps not in B&Q. :) They were a close fit to the very small data wires. I don't have them handy, so can't be more precise, sorry.

I own a ratchet crimper which I use for bigger terminals, but I find it too large and unwieldy for this purpose. I'm talking about a short length of multicore cable, working overhead in a confined space. Sound familiar? A ratchet crimper will preserve the "roundness" of the pin, but this seems not to be particularly desirable here. The hollow pins are soft and a small pair of pliers will flatten them. They then sit making excellent contact with the Index Marine choc block leaf spring (or screw, if no leaf spring), and the nickel plated brass inserts. A crimp made this way with a firm amount of force makes it next to impossible to pull the wires out. The pliers were also suggested by my Furuno radar installer friend. It works for me!
 
I have used choc blocs on two boats without trouble. I make sure they are in a dry place and the cables going into them are well supported. If you solder them they are liable to break and you have a problem when you want to get the mast down. Just dont use cheap ones, at least make sure they have the little clamping tongues!
 
samwise said:
We will have to de-rig this Autumn and that will involve separating the radar cabling that currently runs continuously from mast to instrument.
All the other stuff is on deck plugs, but I have found that deck plugs in multi pin format always seem to suffer badly from corrosion and consequent failure ( albeit temporary) of the unit. Therefore a connection inside the boat is desirable.
I can't really unthread the cabling back from the chart table because that will involve taking down at least half the headlining which, on a Westerly , is a PIA.

I have spoken to the professionals and they say they use simple chocblock connector strips -- which seems a bit Micky Mouse to me, but they say it works. Ideally some sort of waterproof male/female plug and socket arrangement that I can pull through the deck gland aperture would do the job, but I fear they are on the expensive side.

Any ideas/ suggestions welcomed
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use gel connectors used by BT, water tight, good connection, proffessional.
 
Choc blocks are available gold plated from maplins, designed for car hi-fi systems, along with crimps have been in use for my autopilot for 10 years, no corrosion and fine.
 
Split my cable when fitting the furuno radar 7 years ago and used choc block inside a die cast aluminium box. This was connected to the shield by an additional short wire. A very fiddly job but have had the mast down twice in that time.

I will certainly look for some of the small crimp on connectors, but currently for the very fine wire I double the wire back over the plastic coating so the wire is clamped in the choc block by the wire and sheath.

Still the worst part of taking the mast down though. As a note the one time it has not worked when needed was due to corrosion in the connector in the raydome.
 
Back in the late '70's I worked for Decca Radar (becoming Racal Decca Radar while I was there), these Choc Blocks or these More choc blocks were in use in just about every unit made - both small boat and large ship radars.
I know they are more expensive than the cheapies but do give good long term connections.
Opening an account with Farnell is about the only way I have fouind of getting them though.

Cheers

Piddy
 
samwise said:
We will have to de-rig this Autumn and that will involve separating the radar cabling that currently runs continuously from mast to instrument.
All the other stuff is on deck plugs, but I have found that deck plugs in multi pin format always seem to suffer badly from corrosion and consequent failure ( albeit temporary) of the unit. Therefore a connection inside the boat is desirable.
I can't really unthread the cabling back from the chart table because that will involve taking down at least half the headlining which, on a Westerly , is a PIA.

I have spoken to the professionals and they say they use simple chocblock connector strips -- which seems a bit Micky Mouse to me, but they say it works. Ideally some sort of waterproof male/female plug and socket arrangement that I can pull through the deck gland aperture would do the job, but I fear they are on the expensive side.

Any ideas/ suggestions welcomed
Click to expand...
They work Ok, my 2 boats have had them
Stu
 
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