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Author Topic:   Underwater Splices
swist posted 10-21-2014 02:12 PM ET (US)   Profile for swist  
I am replacing the bilge pump and float switch in my Montauk 170. The factory installed units were connected to the boat's wiring with barrel-style crimp connnectors, surrounded with some sort of clear plastic either heat-shrunk or sealed in some other way. These are connectors that will get submerged in saltwater regularly.

What is the preferred technique for making these connections?

fno posted 10-21-2014 06:25 PM ET (US)     Profile for fno  Send Email to fno     
Solder is better than a butt splice crimp connector in any environment. That and the shrink tube both required bench work to be done right. Use good quality shrink tubing that has glue on the inside to cover the individual conductors that have been soldered. Then put a larger diameter piece of shrink tube over them. Last but not least buy some liquid electrical tape( a black, sticky, goop in a can) and coat the ends of the shrink tubing.
jimh posted 10-22-2014 08:07 AM ET (US)     Profile for jimh  Send Email to jimh     
The preferred method to make a splice on a small boat: do not make splices.

Typically there is no conductor on a small boat that is so long that it must be made from two shorter conductors and connected with a splice. Consider replacing any conductors which are made with two or more conductors spliced together with a single new conductor of sufficient length.

For electrical devices (like sump pump or float switch) which are intended to be operated while submerged, and where the devices have integral wiring or conductors embedded to them, be certain to install the devices in a manner so that the connections between the devices' integral conductors and the rest of the boat wiring will occur well above the level where any water is ever expected to exist. The conductors integral to these devices can typically be ordered in different lengths, with longer conductors being an option. The longer conductors will permit installation of these devices in sumps or bilges that are very deep, but the long conductors will permit the electrical connections to be made safely far above the devices' operating level.

If a splice cannot be avoided when installing a new device, and if the conductors on the new device are not sufficiently long to be carried away run into an area that is always dry, then make the splice as carefully as possible and with great attention to preventing water intrusion. The use of irradiated tubing with heat shrinking properties, insulating grease, and glue can be helpful. But it is hard to image a sump so deep on a 17-foot boat that the electrical connections must be made at a point in the wiring that will be below water.

Hoosier posted 10-22-2014 09:12 AM ET (US)     Profile for Hoosier  Send Email to Hoosier     
Harbor Freight has marine heat shrink tubing that has a sealant inside. It melts when heated to form a watertight seal inside the tubing. Solder the wires first.
swist posted 10-22-2014 11:34 AM ET (US)     Profile for swist    
I was going to make the connections where Whaler made them - as high in the sump as possible. Certainly not going to bring the wiring up on deck.

In that location, assuming the pump is working properly, and further assuming the boat does not often take on enough water to submerge the entire sump, the connections would be best described as not continuously submerged, but maybe occasionally. And also subject to salt/fresh water splash.

DVollrath posted 10-22-2014 12:50 PM ET (US)     Profile for DVollrath  Send Email to DVollrath     
Hi Swist,
I soldered & sealed my splices in much the same manner as fno describes. The splices are higher in the rigging tunnel, but I'm sure they get regularly wet. It's been 2 years now without detected problems. I suspect (or maybe hope...) that the splices will last longer than the pump itself.


jimh posted 10-22-2014 07:18 PM ET (US)     Profile for jimh  Send Email to jimh     
I was going to make the connections where Whaler made them - as high in the sump as possible. Certainly not going to bring the wiring up on deck.

You should move the connections to a location where they are as far as possible above the bottom of the sump. I would move them to just below the top of the gunwales.

Hoosier posted 10-22-2014 08:01 PM ET (US)     Profile for Hoosier  Send Email to Hoosier     
My rule is: any wiring on a boat is going to get wet, maybe be submerged, so, make everything as watertight as possible.
kwik_wurk posted 10-22-2014 11:29 PM ET (US)     Profile for kwik_wurk  Send Email to kwik_wurk     
While no splice is ideal solid runs would be best, practicality prevents that.

Locating splice as high as possible is second best option. (While not a 170, on the Montauk I have the bilge wiring is actually a terminal strip mounted on the inboard side of the splash well. The boat would have to have ~12"-14" of water in it to reach this height. Granted I have an aft cover area the hides this terminal strip, but it beats splices going underwater. And the nice thing is if I want to check voltage to the pump, it is a quick flip of the cover and the leads are right there.)

As for water resistant splices, I do have a technique...

parts needed:
-butt splice with integral adhesive heat shrink
-heat shrink tube that is 2" longer than butt splice
-heat shrink that is 4" longer than butt splice (and one size larger in dia.)
-liquid tape
-heat gun

1) Butt splice with integral adhesive heat shrink is the first seal
2) Then seal the ends with liquid tape (takes a 1/2 day to cure)
3) Then coat the entire butt splice with liquid tape, and simultaneously put a 1st heat shrink tube over and shrink/seal. (And without catching fire!)
4) Repeat step 3 one more time.
5) Seal ends with liquid tape

The end result is a rather stiff section of wire, but I have gotten several years out of a few splices like this.

endus posted 10-23-2014 11:00 AM ET (US)     Profile for endus  Send Email to endus     
I have been redoing a lot of the electrical on my new-to-me 04 Montauk 170. I am soldering everything I possibly can. In fact, my nav unit was not working the last time I took the boat out and I couldn't find the problem. Finally I jiggled the (brand new) crimped ring connector at the fuse panel I installed and it came on. I'm going to replace all those crimps with soldered connections and heatshrink.

For my bilge pump I soldered the wires, put heatshrink over each wire, squeezed dielectric grease into the heatshrink, shrunk it, and then I believe I did a larger piece of heatshrink over both wires. Then tape....lots of tape.

The old connectors corroded where the wire entered the barrel connector, I figure what I did should be at least marginally better than those.

Liquid electrical tape is a fantastic idea. Can't believe I didn't think of that.

fno posted 10-23-2014 06:02 PM ET (US)     Profile for fno  Send Email to fno     
Another thought. Heat shrinkable and regular insulated butt splices, ring terminals, and spade connectors are all a compromise. A far better approach is an un-insulated ring or spade connector can easily be crimped and then soldered and a piece of heat shrink should be shrunk over the barrel where the wire is.

With regards to spade connectors, it is possible to solder them to the junction as well and this greatly improves the long term reliability of the connection. The only drawback is you need to unsolder it if it needs to be removed.

Last thought of the day. Always try to use Ancor wire products that are pre-tinned. Copper wire is great by itself but exposed in a marine environment will corrode to the point of failure. Much of this ordinary wire will be corroded up inside the insulation also, leaving one with a major rewire.

Disclaimer: I do not have any interests in any solder, soldering iron, or connector companies. Just to much electrical work the last 30 years. Further advice can be found in mil-spec shop practice journals. Especially the ones for submarines and jets.

fno posted 10-23-2014 06:12 PM ET (US)     Profile for fno  Send Email to fno     
Another plug for solders value. I have a 2005 210 Outrage. From the first year I had trouble with my port/starboard lights either not working or flickering at night. Each time I would remove the cover (Perko) and clean both the bullet bulb and the copper plated tabs that hold the bulb. In addition, silicone was used to ward off moisture. Works for about six months whether used or not. Sometimes less, so I purchased new light fixtures(Perko) and new bulbs with LED technology. I soldered the fixtures in, insulated them with shrink and liquid tape and installed the bulbs. Before installing the red and green covers, I soldered both ends of the bulbs to the tabs. That was four years ago and they always come on. In the future, as change out any other bulbs or lights on my boat they will surely be LED technology.
tedious posted 10-24-2014 07:50 AM ET (US)     Profile for tedious  Send Email to tedious     
Soldering is always a good thing. So is adhesive-lined heat shring tubing to follow the soldering, or adhesive-lined heat-shrink crimp connectors for where you can't solder.


fno posted 10-27-2014 11:00 AM ET (US)     Profile for fno  Send Email to fno     
Any of you old timers out there have any old fashioned solder with some actual lead in it? If so, sell me a roll or even a piece. The stuff they sell today is crap!!! Maybe I can import some from China.
jimh posted 10-28-2014 10:30 AM ET (US)     Profile for jimh  Send Email to jimh     
Frank's mention of a change in solder is quite acute. I have some old rolls of traditional 60-Sn/40-Pb tin/lead alloy solder, and it works very well. The newer solder formulations are much harder to use. In our electronics shop we called them "Communist-solder."

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