The term Dressing Wire refers to the process of bundling wire together in an orderly fashion, which in effect creates a wiring harness. The modern method of accomplishing this is with cable ties.
There are a wide variety of cable ties for almost every application imaginable. For the boater, it is important to buy cable ties that are UV rated if they are going to spend anytime out in the sun. Non-UV rated cable ties will eventually deterioate if left exposed to the sun.
Regardless of what type of cable tie you use, it is important to consider using a cable tie gun. A tie gun serves two purposes; it applies the proper amount of tension on the cable tie, and it cuts the end clean and flush. An incorrectly tensioned cable that is too tight can break during installation, or can over time cut into the wire's insulation. Cable ties that are not cut flush become a safety hazard. It is not uncomomon to receive a cut on your arm or hand by reaching into a confined area and receiving a scratch from a cable tie end.
Cable tie guns can be expensive, but a good source to purchase them cheaply is on-line auctions, such as eBay. I purchased this military grade cable tie gun for around $40 from an on-line auction.
While cable ties are the most common method of wire dressig, there is an alternate method that is tried-and-true, and has been used on aircraft, ships, and military equipment for over 60 years. This method is known as cable lacing, and while not a concept that may be familiar to pleasure boaters, I think you'll find that the method is easy to learn, looks more attractive, and is a superior method of bundling wires in your boat.
The chief advantage of using cable-ties is that they are easy to install, so they work well in prototyping (for instance, you may need to add wiring to a bundle several times during the life of the boat). However, there are several disadvantages as well:
Cable lacing on the other hand has the advantages of being quite inexpensive; you can purchase a 500 yard roll of the lacing cord for around $20. This is probably much more than enough to satisfy a lifetime of boating projects. The chief disadvantages are that it is more labor intensive, and cannot easily be modified to add more wires to a bundle.
For these reasons, I submit that a combination of both methods (lacing and cable-ties) would have an application to the boat project. While lacing may be somewhat of a lost art - its easy to learn, and you will be lacing your projects in no time.
The basic concept of lacing is to use a flat cord to tie the cable bundle together. The original cord was known as cat-gut, but for as long as I can remember, nylon has always been used.
Lacing cord looks a bit similar to dental floss, although it is typically wider. The main requirement is that he cord be flat, because otherwise, the lacing tends to cut into the wiring. Lacing cord is available in either waxed or unwaxed versions; I prefer waxed, because it tends to stay-put as you are lacing the cabling. You will want lacing cord that meets Military Specification MIL-T-43435B, which is available commercially at many on-line retailers. While you are not building the Space Shuttle, it is very common in the wire and cable industry to use Military Specification rated materials. As a side note, the common RG-58 Coax cable is actually a Military Specification, so its not really overkill to use this material in a boat.
Once you get a bundle of wires together, you will want to start the lacing near the end which is typically near one end. There are several different types of knots that can be used, but I prefer a "square-knot with two lock stiches" because it is the quickest and simplist method. Once you pull everything tight, you should end up with the end as shown.
Once the knot is made, you simply make a series of lock stiches along the length of the bundle in roughly equal intervals, again pulling tight as you go. Waxed cord helps here, because the knots tend to stay put as you lace the bundle.
Finally, when you are at the end of the run, simply make another square knot to secure the lacing. I also like to put a dab of glue on the knot, which ensures the lacing will not come undone.
Once you get the hang of it, you can try your skill at breaking out branches of the wiring harness along the lacing. This will take some time to be sure, but the results will be worth it.
An alternate method is to make descrete "ties" where a start type knot is made every 1/2 inch, and cut off so that each knot is independant. There is little advantage in this, other than there is no chance of the lacing unwraveling, but the disadvantage is that it is much more labor intensive.
There is really no wrong way to lace the cables. Try your hand at lacing - you can even use dental floss to practice.
A third method is to use wire Loom. Loom is a split tube or spiral wrap that is sometimes used to contain the wiring. It can be used in addition to cable ties or lacing, or used by itself. When used by itself, the advantage of the loom is that it is easy to add or remove wires. Loom also offers the most protection to the wires within. The chief disadvantage is that the loom material is expensive compared to the other two systems.
Wire loom is quite common in the automotive and home improvement industry, and is available in various diameters. It is commonly available at auto parts stores, electronics stores, and home centers. Wire Loom can be purchased that meets Military Specifications as well.
Dressing wire not only looks great, it orgainzes your wiring job, provides protection and support to wiring bundles, reduces trip hazards, as well as the likelyhood of snagging a wire. So take a bit of extra time on your next project and dress your wiring.