My 2¢.....
It is important to note that the ABYC does NOT ban the use of solder on boats. It makes suggestions about how to more
safely use solder on a boat and that suggestion is a mechanical connection, then solder, and then properly strain relieved. In my 35+ years on and around and working on boats I can practically count on one hand the number of times I have come across "properly" soldered wire joints. Okay it's really more than that but the point is most solder joints I come across in the marine environment SUCK because they were IMPROPERLY executed....
Over the last 35+ years having worked in three different boat yards, on "mega-yachts", with a friend who is a marine surveyor and on my own boats and customers boats it has allowed me to see with a large, n=xxxxx, of solder failures. On your own boat, n=1, failures might be quite rare, but as the n=X grows, n=500, n=3000, n= 5000. n=10,000 etc. so does the rate of failure/success between solder and crimps on boats.
The failure rates I have seen for soldered connections is significantly higher than that of crimped connections. Why? I suspect because most folks just don't know how to do it
properly.
When done correctly they are fine, and some folks DO know how, but unfortunately that happens very, very rarely, in my experience. The PO of my own boat was an EE and still made horrible and unsafe soldered joints. When it comes to solder it was a pathetic mess when I got it.
Keep these points in mind:
FACT: The ABYC does not prohibit the use of solder only prohibits it as the sole means of mechanical connection.
FACT: No means of wire twisting count as a mechanical connection under ABYC E-11. This was clarified through standards clarification review a number of years ago. WU or Lineman's splices are not intended for stranded wire and are specifically banned under a number of standards including the NASA standards and they also don't count under ABYC.
Here are some other interesting points from ABYC E-11:
"Conductors shall be at least 16 AWG. EXCEPTIONS: 1. 18 AWG conductors may be used if included with other conductors in a sheath and do not extend more than 30 inches (760mm) outside the sheath.” 11.16.1.1.2."
"Conductors used for panelboard or switchboard main feeders, bilge blowers, electronic equipment, navigation lights, and other circuits where voltage drop must be kept to a minimum, shall be sized for a voltage drop not to exceed three percent”.
"Conductors used for lighting, other than navigation lights, and other circuits where voltage drop is not critical, shall be sized for a voltage drop not to exceed 10 percent.”
"Solderless crimp on connectors shall be attached with the type of crimping tools designed for the connector used, and that will produce a connection meeting the requirements of E-11.16.3.3.” 11.16.3.8."
"Current-carrying conductors shall be routed as high as practicable above the bilge water level and other areas where water may accumulate. If conductors must be routed in the bilge or other areas where water may accumulate, the connections shall be watertight.”11.16.4.1.6."
"Terminal connectors shall be the ring or captive spade types.” 11.16.3.4."
"Twist on connectors, i.e., wire nuts, shall not be used.” 11.16.3.6."
"Ring and captive spade type terminal connectors shall be the same nominal size as the stud.” 11.16.4.1.12."
"Solder shall not be the sole means of mechanical connection in any circuit.”11.16.3.7."
Some other things to consider:
FACT: You as a private boater do NOT need to comply with the ABYC
CAUSE FOR CONSIDERATION: Your surveyor surveys to ABYC standards and your insurance company underwrites your boat based on the surveyors report.
These are just a bit of the "insurance/survey" items I have had to deal with over the last few years:
*Bond a keel stepped mast to external ballast (after a strike claim)
*Bond numerous boats for AC Grounding to DC Grounding
*Add over current protection where it did not exist (house banks for example)
*2 Boats for the AC inlet / breaker 10' rule
*1 Boat for an improper AC main breaker (not double pole)
*Multiple boats for GFCI outlets
*Multiple boats for lack of DC over-current protection
*Multiple boats for LPG system issues
*1 Boat for AC/DC isolation (cover for AC) behind AC/DC panel
*Multiple boats for fuel system issues (too many to list)
*1 Boat for a reverse polarity indicator
*Approx three boats for non compliant battery chargers
*2 Boats for ignition protection issues on gas boats.
*1 Boat for lack of a bilge blower
*Improper bonding of chargers and inverter/chargers
*1 Boat for a bilge pump alarm
*Multiple boats for deteriorated below waterline hoses
*Remove a non compliant on-demand water heater (Excel)
*Multiple battery system compliance issues including venting, acid containment, over current protection etc..
*Multiple unsafe termination issues (solder, wire nuts, improper lug stacking etc.)
*Steering system failures (meat hooks etc.)
There are probably more that I am just forgetting... Insurance companies and surveyors today are playing a CYA game. In todays day and age it does pay to use the available safety standards as a solid guideline for boat upgrades. The survey industry uses them so the closer your boat is to those guidelines (ABYC) the better chance you will have a skating through clean on an insurance survey. It is getting tougher and tougher to find a
lick & stick surveyor these days due to the litigious nature of our society. I am sure they are out there but NAMS and SAMS are getting very structured and precise in what they want to see...
Doing the best you can to ensure as close to the safety standards as you can get will ensure passing an insurance survey. Crimp then solder is FINE. Insurance companies are getting much more strict in what they want to see upgraded or fixed in order to maintain insurance coverage. There is no such thing as being "grandfathered" by an insurance company anymore.
I had one owner who pulled the "I'm grandfathered" card on the insurance company and they dropped him at renewal. He had an extremely trough time finding insurance for his forty year old boat. In the end it cost him $700.00+ more per year than the $120.00 in safety requirements the insurance company wanted to see. D'oh!!!!
NOTE: "Lick & stick" is a term for those of us in states that require State inspection stickers on cars. Anyone who's ever owned an old car knows what a "lick & stick" garage is..... A few extra dollars and the problems just go away and he licks the sticker and slaps it on... (wink)
Points to ponder over:
As one who lives in the North East, where nearly every home has a deep artesian well, with LONG wire runs and fairly high amp draws, we just don't see moisture failures with heat shrink butt connectors.. Yes boats are a
humid environment. How
humid are the wires sealed 200+ feet below the surface, that live underwater for their entire working life span and then last for 15, 20 years or more or until the well pump fails? Pretty impressive stuff for a heat shrink butt connector. If your boat is submerged for more than a few minutes you have a lot more to worry about.
Keep in mind that nearly every industry uses crimps reliably, without solder, including aerospace, space, automobile, medical, laboratory, truck industry, heavy equipment and have been for years and years and years. I was working on my neighbors John Deer tractor a few months ago and every single connection in that tractor is crimped.
The artesian well at our old house was 245 feet deep and was a true artesian. It over flowed/bubbled out the well cap almost all year. The crimped butt splices were about 240 feet below ground and totally submerged... These wires connecting the well pumps are crimped and adhesive heat shrunk with what are called Stakons (basically adhesive lined butt splices). These bare copper, non-tinned, wires have been under water now for approx 16 years only crimped and heat shrunk. I think that today that same well pump is still going strong..
Crimping solder tinned wire:
If anyone gets really bored NASA has some great wiring standards as does the US Military. It is exciting reading (NOT). My crimp tools all meet or exceed MIL-T- 7928G because it is the most stringent for crimp terminals. The ABYC standards for crimp tensile strength, by comparison, are PATHETIC....
Keep in mind that crimping solid copper wire or solder tinned wire can also damage the dies on the crimp tool and throw it out of calibration..
Here's what NASA's standards have to say:
"4.3.4 Crimping Stranded wire shall be used for crimping (Requirement). Crimping of solid wire is prohibited. Crimping of solder tinned wire is prohibited."
The way I tend to look at it is this way. When you and your boat are far off shore you might as well be in outer space because it is you, you and you who are there to deal with any issues..

Do what ever you do WELL......
Just because I am an ABYC member and ABYC certified does not mean I stop there. I push to exceed the ABYC standards and that is why I read and study other standards and incorporate them into my own
standard of work, especially when they can be beneficial and BETTER than ABYC...
Soldering after a crimp has been made is fine provided you:
*Know what you are doing, IME most don't. (in my line of work that amounts to about 98% of what I come across did not know what they were doing when it came to solder.).
*Use a
heat sink to prevent solder creep up the wire.
*Use the correct solder.
*Use the correct wire prep or rosin core solder. (Non-activated R or NC or a high quality RMA rosin core flux from a known and trusted manufacturer are about the only products that should be used in the marine environment. Be aware that there are many RMA fluxes out there that are not acid free. Get this acid into the fine strands and it can be impossible to clean out and will lead to corrosion.)
*Use proper strain relief or adhesive lined heat shrink.
*Use the proper crimp terminals for crimp/solder which are different than typical insulated terminals and rarely as robustly built as the insulated ones or heat shrink ones.
Crimp/solder terminals utilize a B or F type crimp also known as D-Sub etc.. They are extremely tough to find in a good tinned robust build AND they require a specific crimp tool..
Image Courtesy Innova
*Use the proper crimp tool for the solder/crimp terminals which most don't own or have on-hand if they have been using a crimper designed for insulated crimps.
In short doing crimp then solder requires different tools, proper training and more labor than just using a good quality crimp tool and high quality terminals..
There are billions & billions of crimps in use world wide, maybe even trillions. Yes solder makes a great electrical connection, no one would ever dispute that, but apparently it is very tough to do
correctly & from what I see on boats...
People botch crimps too, lets not kid ourselves. You can't get caviar results with a dime store tool and dime store terminals, but people try all the time.
Nigel Calder from Boat Owners Mechanical & Electrical Manual Pg. 122 said:
Soldering is a controversial subject. A properly soldered connection creates the best electrical connection, but all too often the soldering is not done properly. In any case, ABYC regulations require that every joint have a mechanical means of connection other than solder. The reason for this is that if the joint gets hot (through excessive resistance or a high current flow) the solder may melt and the joint fall apart. So solder often becomes just an adjunct to a crimped connection, but in this case the solder wicking up the cable creates a hard spot, which is then liable to fail from vibration. The consensus among professionals is that a properly made crimp, done with the proper tools, is frequently a more reliable termination than soldering.