how to run transducer wire through hull

[mlrman]

Hi,

the previous owner of my boat added a Humminbird Piranha fish finder, but ran the transducer wire through the combustion vent in order to get through the hull of the boat.

I don't like the way the wire looks running through the vent, but how do I run it through a hole I drill in the hull? One end of the wire is attached to the transducer, and the other end is attached to a plug, so the hole drilled through the hull would have to be at least half an inch wide.

Can I cut the wire in half, then fish one end through a 1/4" inch hole and re splice?

The original manual doesn't specify, and I searched here already.

Thanks for any ideas.

 

[Boatist]

Re: how to run transducer wire through hull

Drill the half inch hole and install then get one of the stainless steel Covers that cover the hole. Put some sealent around the wire and install the cover. Do not cut the wire.

Other choices is to go over the transom or thru an existing hole for wires, cabels or fule lines.

Last choice leave it the way it was.

 

[5150abf]

Re: how to run transducer wire through hull

I ran mine up and over the ransom then had it follow the control cables to the console, used some wire guides to secure the cable and it looks pretty clean.

DO NOT cut the wire, it is a sheathed wire, there is a wire mesh around the bundle of wires and you will never ever get it back together right and they aren't cheap.

 

[dingbat]

Re: how to run transducer wire through hull

DO NOT cut the wire, it is a sheathed wire, there is a wire mesh around the bundle of wires and you will never ever get it back together right and they aren't cheap.

Its not rocket science. If you can splice an extention cord back together, you can splice a transducer cable.

 

[etracer68]

Re: how to run transducer wire through hull

Drill the size hole needed to get the plug through, and put the right cover over it with sealent. That is the right way. Also it can be removed if you ever want to upgrade. I wouldnt buy a used unit if the transducer wires were cut, and spliced together.

 

[Fireman431]

Re: how to run transducer wire through hull

As was stated, drill the hole and cover the entry (after being sealed) with a clamshell cover.



If you look at any transducer installation manual, they specifically say DO NOT cut the cable. You will ruin it. Splicing the wire will screw up the impedence that is was designed to operate at.

 

[dingbat]

Re: how to run transducer wire through hull

If you look at any transducer installation manual, they specifically say DO NOT cut the cable. You will ruin it. Splicing the wire will screw up the impedence that is was designed to operate at.

There is absolutely no reason why you can't splice a transducer cable. Yes, the impedance of the cable will change, but on the same magnitude of peeing in the ocean in West Palm Beach and expecting the water level in New York City to change. It?s a nonissue. Airmar even makes a splice kit to facilitate the process.

The reason why they say to not cut the cable is probably two fold. First off, there is an electrical hazard. A transducer is a capacitance device. They will knock you on your butt if they are holding a charge when you cut the cable. The other is the skill required to make the splice in a marine environment. Something the average Harry Homeowner doesn?t possess.

http://www.airmartechnology.com/uploads/installguide/17-037-01-rev03-ps.pdf

 

[Fireman431]

Re: how to run transducer wire through hull

mlrman - maybe this will halp with your installation

From the installation manual:

Step Six - Route the Cable
There are several ways to route the transducer cable to the to the area where the
control head will be installed. The most common procedure routes the cable through the
transom into the boat.

Inside the boat there is often a channel or conduit used for other
wiring that the cable can be routed along. Do not cut or shorten
the transducer cable and try not to damage the cable insulation.
Route the cable as far as practical from the VHF radio antenna
cables or tachometer cable to reduce the possibility of
interference.

If the cable is too short, extension cables are available to extend
the transducer cable up to a total of 50' (15 m). Call Humminbird
Customer Support for more information.

Follow these steps to route the cable through the transom:

1. Drill a 5/8? (16mm) hole above the water line. Route the
cable through the hole.
2. Fill the hole with silicone sealant.
3. Place the escutcheon plate over the hole and attach with the two #8 x 5/8? (16mm)
screws.
4. Secure the cable by attaching the cable camp to the transom using a #8 x 5/8?
(16mm) screw.
Note: The transducer will pivot up to 90 degrees in the bracket. Allow enough
slack in the cable for this movement. It is best to route the cable to the side of the
transducer so the cable will not be damaged by the transducer during movement

 

[jonesg]

Re: how to run transducer wire through hull

1. Drill a 5/8? (16mm) hole above the water line. Route the
cable through the hole.
2. Fill the hole with silicone sealant.
3. Place the escutcheon plate over the hole and attach with the two #8 x 5/8? (16mm)
screws.
4. Secure the cable by attaching the cable camp to the transom using a #8 x 5/8?
(16mm) screw.
Note: The transducer will pivot up to 90 degrees in the bracket. Allow enough
slack in the cable for this movement. It is best to route the cable to the side of the
transducer so the cable will not be damaged by the transducer during movement

Wow really bad instructions with that sillycone.
No wonder 70% of the boats out there have wet transoms.

Drill the hole, seal with resin, multiple coats if needed.
Run cable through and install the sealing plate.
Bed all screws with 5200 marine sealant.

 

[Fireman431]

Re: how to run transducer wire through hull

That was from the installation manual!! Don't put that back on me! I just copied & pasted it. I would use either 4200 or 5200 as well. Or chewing gum. Bubblicious works great!

 

[ufm82]

Re: how to run transducer wire through hull

Buy a shoot-thru tansducer and epoxy it in the bilge. Issue solved and no holes in your transom. DONE!!!

 

[JimS123]

Re: how to run transducer wire through hull

Wow really bad instructions with that sillycone.
No wonder 70% of the boats out there have wet transoms.

When I bought my current boat brand new I re-installed the depth finder / transducer that I had previously taken off my old boat. Both were installed the way listed in the subject installation instructions, using a marinetex-type sillycone, intended for underwater service.

Last year I replaced that system with a brand new depthfder, and when I installed the new transducer I found that the hole in the transom was still sealed very tight, and there was absolutely no rot anywhere. In fact, it took a man and a boy to get the old wire out!

The original installation / sillycone application was done 26 years before. What did I do wrong?

 

[mlrman]

Re: how to run transducer wire through hull

Its not rocket science. If you can splice an extention cord back together, you can splice a transducer cable.

I mean, that's my thought exactly! I have spliced many "Radio Shack style" adapters together in my day. I can't imagine splicing the cable with proper shielding would cause any problems. The unit is out of warranty anyway, so that's not an issue. Thanks for the replies, everyone.

 

[mlrman]

Re: how to run transducer wire through hull

There is absolutely no reason why you can't splice a transducer cable. Yes, the impedance of the cable will change, but on the same magnitude of peeing in the ocean in West Palm Beach and expecting the water level in New York City to change. It?s a nonissue. Airmar even makes a splice kit to facilitate the process.

The reason why they say to not cut the cable is probably two fold. First off, there is an electrical hazard. The other is the skill required to make the splice in a marine environment.

http://www.airmartechnology.com/uploads/installguide/17-037-01-rev03-ps.pdf

my splice would be half way along the wire, where it's tucked up under the side panels and kept dry.

good link! thanks.

 

[mlrman]

Re: how to run transducer wire through hull

That was from the installation manual!! Don't put that back on me! I just copied & pasted it.

I have the manual, and that IS what it states. I hate to drill a freaking 5/8 hole through the hull though. And yes there is a channel to run wires through the engne compartment to the rest of the boat, but again, getting through the hull itself for the transducer is the issue.

Since the fish finder came with the boat and I can afford a new one, I think I am going to try the 1/4" hole and splicing idea. IF that gives me problems, I will buy a new unit and drill the "recommended" 5/8" hole and use resin to fill the hole, not silicone. I'd still use a termination cover, like used with my speedo's pick up tube, so it looks nice. I am particular that way.

Anyway, this forum rocks, and I appreciate all the replies!

I'll post my results so it may help someone in the future.

 

[Outsider]

Re: how to run transducer wire through hull

No wonder 70% of the boats out there have wet transoms.

70%, huh? And to think, I read on the internet it was only 17% of those that had transducers wired thru the transom. Ya just can't get accurate numbers anymore ... :facepalm:

 

[JimS123]

Re: how to run transducer wire through hull

If you have to drill a hole anyway, I don't see the difference between 1/4" and 5/8". You use a termination cover either way, so you can't see the hole in either case.

I can see removing the plug and re-soldering it back on, but cutting the cord in the middle and actually splicing it back together is risky. Those cords are designed very specifically for the instrument and any electrical interference will give you erronious results. Once I ran a cord in the wire conduit along with all the engine wires. It was an electric shift Evinrude. The depth finder worked like crap until I relocated the cable down the port side in an empty tube.

 

[Woodnaut]

Re: how to run transducer wire through hull

I built my boat. The transom is marine plywood covered in fiberglass. I drilled the requied hole size through the transom (5/8" or thereabouts) and then sanded, cleaned, and coated the inside of the hole with epoxy resin. The provided a very effective water seal for the newly exposed plywood. The following day I ran the cable through the transom, filled and closed the hole with silicon, and then capped the hole/cable on both sides of the transom with small clamshell covers. That was 10 years ago. I had to replace the cable earlier this year so I dug it out. (Which was not all that easy.) The cable and the transom were both in excellent condition. When I originally built the boat I had the option of drilling a small hole and splicing the cable, but I simply chose not to mess around with the equipment. (Would have voided warrantly.) Also note that running the transducer wire directly next to speaker wires can produce interference.