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Messages - J_Sail

Pages: [1] 2 3 ... 10
1
Main Message Board / Re: Negative battery terminal HOT
« on: September 14, 2018, 11:11:04 AM »
You might have a wiring error, or you might have one or more batteries with shorted cells from old age.  Check the open-circuit voltage of each battery with it fully disconnected.  If one or more of them is significantly lower than the others, then that battery might have a shorted cell, which could produce your symptoms. A shorted cell will reduce the output voltage by 1.2v. 

(A discharged battery may also show a low voltage, but that would have been resolved after sitting on your charger, and with all the batteries in parallel on your previous charger, they should all be at the same state of charge absent things like shorted cells.)


Ideally also check each one with a modest load across it (a few amps), but finding a good device to load it can be challenging.  I own an inexpensive commercial 12v battery tester, which can apply loads of up to 100amp, but I also use a 6 ohm 50-watt resistor that I bought somewhere decades ago. That draws on the order of 2 amps, depending on actual battery voltage.

2
Main Message Board / Re: resistor?
« on: September 05, 2018, 09:42:03 PM »
Just to be clear; the resistor does NOT in any way affect the speed of the fan. Its purpose is to vary the speed of the compressor in the Danfoss BD35 models that support it.  With a variable speed compressor you can run it at the slowest speed that will cool your box.  The benefit is that the compressor is more efficient at slower speeds; running the compressor slowly for a longer period of time takes less total electricity than running it faster for a shorter time. 

Skipping the resistor won't hurt anything; the compressor may run for a shorter period each day without it, but since it draws proportionally more power than the increased cooling the speed provides, in the end you spend a bit more energy when it runs faster than optimal.

http://files.danfoss.com/TechnicalInfo/Dila/06/bd_compressors_04-2007_pk100c802.pdf
http://www.suremarineservice.com/LT201-UNIT-ACDC.html

3
Main Message Board / Re: Solar panel connections
« on: September 03, 2018, 10:18:11 PM »
At the charging currents you will get from a pair of 100w panels, the voltage drop is insignificant. You probably, though, want the connection to be such that the house bank gets charged regardless of the position of your master switch. I think that's why Jon is requesting a schematic.

4
Main Message Board / Re: Electric windlass circuit breaker button stuck
« on: August 07, 2018, 07:55:47 PM »
One of my prohibitions against the use of silicone is near electrical contacts that are subject to arcing. That means relays, switches and circuit breakers. The reason is that an arc can convert silicone to silicon-carbide, an extremely hard insulator. The process is slow, so it's mostly a risk on relay contacts that actuate frequently.  So, probably no significant harm using it on your windlass breaker, but ideally, you would be better off using a product that does not contain silicone.

jeremy

5
Main Message Board / Re: Water Heater Leak
« on: June 23, 2018, 11:02:09 AM »
I own both of these and both are good.  Bought first one in 2014 for $16 for engine and other uses, and it's still serving me well. Bought the second one for $26 a few months ago for HVAC and other stuff at our offices where I needed a narrower "cone" of sensitivity for reading things at a greater distance - also good. For engines, the first one is fine.

https://www.amazon.com/gp/product/B006V4WNYU
https://www.amazon.com/gp/product/B00K5QVBCU


6
Main Message Board / Re: Water Heater Leak
« on: June 23, 2018, 12:32:39 AM »
Total shot in the dark, and I may be way off base, but I recall an incident from decades back of an engine that overheated and produced insufficient power that ultimately turned out to be exhaust manifold obstruction. The exhaust gas back pressure both reduced the power and increased operating temperatures under load.

7
Main Message Board / Re: Catalina Electrical control panel
« on: June 21, 2018, 04:02:27 PM »
The Blue Sea panels are excellent. There are a lot of choices to make when custom configuring one. Jon has recent experience on designing one for his boat, and I previously helped another owner on this forum design his.

The folks at Blue Sea are very helpful with pre-sales questions and after-sales assistance. While the panels are not cheap, they are not as expensive as they first look, if you have a professional order it for you thru a place like WestMarine. Blue Sea gives them a very large discount, so even if your electrician takes a small markup, you may end up paying significantly less than full retail price.

Jeremy

8
Main Message Board / Re: shaft size
« on: June 11, 2018, 08:08:15 PM »
The short answer is that it for the purposes of preserving the zinc surface where it contacts the prop shaft and mounting bolts, Ox-Gard is probably no better or worse than any grease that adequately blocks water from contacting the zinc in the interface area. For reasons I may address in a longer post later, the small amount of powdered zinc and graphite contained in the grease is unlikely to make a difference.  So feel free to use it, just donít expect it to perform any better than a grease that is not metal-filled.

For other uses involving electrical contacts, the graphite and zinc are unlikely to improve connection quality. In some cases (high voltages or sensitive hi-impedance circuits), the graphite and zinc can actually be detrimental.  The net of it all, is that for most uses, non-metallic greases are best; for many of the applications where metal filling sounds inviting, it is actually useless or potentially even detrimental.

Like I said, I will try to write up something more thorough later.

Regarding using a plastic washer and PTFE tape to isolate the Stainless Steel bolts from the zinc - once there is any electrical contact at all (which there will be regardless of your measures), you have formed the electrical corrosion cell.  All you can do then is try to control how much of the S/S surface is exposed to the water and what surface of the zinc performs the protection. The PTFE tape may seal some area of the S/S from seawater and thereby reduce the electrical current flow from it thru the water (that's what consumes the zinc).  The washer will not do anything at all (other than potentially reduce the effectiveness of the lock washer). The only way an insulating washer helps is if it prevents ALL electrical contact between the two dissimilar metals, which isn't going to happen when the threads cut thru the tape and make intimate contact with the zinc elsewhere. So, maybe PTFE tape seals out water over a larger area of the S/S bolt for longer than grease, maybe not.  Only an experiment can tell us.

In the end, the zinc is there to sacrifice itself to protect the prop shaft. So long as there is any electrical connection left between the zinc and the shaft it will do its job. So, unless the zinc erodes so badly as to lose all electrical connection to the shaft (or wobble and become unbalanced), I can't see why it matters. 

Disclaimer - I am an electrical engineer (with special knowledge of contact lubes), but very limited experience with the deterioration pattern and rate of prop zincs, so I defer to folks such as MaineSail and others who have changed out zillions of them.

9
Main Message Board / Re: shaft size
« on: June 07, 2018, 10:47:49 PM »
Ken,
In one of your posts you referred to SuperLube as being the same as Tef-Gel. That suggests you were referring to Super Lube Multi-Purpose Synthetic Grease, which is not listed in the email from Kevin Wall. His email listed their Silicon Dielectric grease, which does not only doesn't contain PTFE, it has an entirely different base. For use in blocking galvanic corrosion between dissimilar materials (such as a stainless bolt thru a zinc or aluminum fitting), you want either Tef-Gel or Super Lube's Synthetic grease. Both the PTFE particles and the synthetic base help maintain the protective coating and help seal out moisture. Their silicone dielectric grease probably won't perform as well. I'm surprised they didn't list it in their email to you. Besides, silicone should be avoided where not needed, due to its tendency to creep long distances, contaminating other surfaces, and later interfere with epoxy, finish, and sealant adhesion.

****
BTW everyone - greases labelled as "dielectric" as still fine on electric connections; as Ken stated before, they get squeezed thin enough for the microscopic peaks of the metal to poke through the grease and make a fine connection. Dielectric refers to the fact that the grease in bulk form won't short out adjacent contacts or breach an insulator. Similarly, some greases labeled as "conductive" such as DeoxIT, are not really conductive at all; they just rely on the same phenomenon of being squeezed thin enough to allow the contacts to touch on a microscopic scale.

Jeremy

10
Main Message Board / Re: shaft size
« on: June 07, 2018, 03:57:06 PM »
Yes, you should get more than enough contact between a zinc and the shaft, even with Tef-Gel applied.

However, for some electrical connectors there is legitimate concern that the action of sliding the connector together, repeated enough times, can cause a microscopic smearing of the PTFE over a large enough area to cause a microscopic, but significant separation of the contacts, resulting in increased resistance.  That caused one manufacturer to reformulate their electrical contact lube to remove the PTFE particles.  I don't think that concern applies to most of your on-board uses.

I have a friend (we worked together as electronics engineers for years) in the contact lube business, so I tend to read the scientific papers from time to time. In most cases, for electrical contacts, a thin film of a very light viscosity anti-corrosion liquid is best, rather than a grease. The thin film protects fine and has less of a tendency to trap moisture or contaminants. That said, I have not seen any research on what works best below the water line, and hi-pressure/clamped connections are a different animal, anyway.  I suspect that Tef-Gel or most any marine-rated grease or anti-seize should be fine. 

Note that SuperLube makes a special anti-corrosion gel that does not use PTFE particles.  I don't know how well it protects underwater though. In turbulent conditions it might not stay in place around the attachment bolts as well. Anyone want to test it?

https://www.homedepot.com/p/Super-Lube-3-oz-Tube-Anti-Corrosion-Gel-82003/202932733


11
Main Message Board / Re: sikaflex 291 70ml tube
« on: May 01, 2018, 09:31:17 PM »
Not to throw a curve ball, but you may want to consider 3M 4000UV. It is a polyether-based sealant that has adhesion characteristics somewhere between 3M4200 and 3M5200 for most materials. It has a wider range of substrate compatibility than most polyurethanes (4200/5200) and is resistant to UV, making it suitable above the waterline, as well as below. It also is vastly less toxic,  and less likely to cause skin reactions if it gets on your hands.

At some point in the past, 3M did not rate it for below waterline use, but they do now.

Unfortunately, it tends to be slightly more expensive, so a 3oz tube may not save you anything versus a full 10 oz cartridge of Sikiflex 291.

https://www.amazon.com/3M-Hybrid-Adhesive-Sealant-Multiple/dp/B00VFIQNUC

12
Main Message Board / Re: Ice box gasketing
« on: April 26, 2018, 05:08:15 PM »
IF the icebox has an area that consistently sits below freezing (e.g. for making ice cubes) then there is an advantage to sealing  against air transfer, in that it helps reduce the buildup of frost. Another possible reason to add insulation would be to reduce power consumption for lengthy cruising.

Other than that, it sounds like a project without great ROI. Someone should make/sell a nice insulating slab with a cutting board on the top surface.

Jeremy

13
Main Message Board / Re: Pencil Zinc Question
« on: April 10, 2018, 04:47:43 PM »
You would think it would be a problem, but I did some informal testing on various threaded fittings and in each case the treads cut through the tape and made excellent contact. It's easy enough to test after threading it in, so you may want to run the test yourself to be certain. Just check for continuity between the head and the surrounding metal.

But, since you remove/replace the zinc relatively frequently (so seizing up after being in there for years is not a risk), it may be easier just to use a bit of pipe dope if you are worried and testing with a meter is too much trouble.

Jeremy

14
Main Message Board / Re: Seized Stainless Nuts - Nut Splitter?
« on: March 31, 2018, 09:25:47 AM »
Finally found the perfect nut splitter, one that MaineSail would be proud to own:

https://www.amazon.com/Splitter-Cutting-Head-110-115Mm-AGN-ENE-NSH110115/dp/B00C3IEN7I
 :clap :clap :clap

My only complaint, is that for $19,909.80, it should really come with free shipping. And it's only the cutting head, not the full tool.
 :cry4`

15
Main Message Board / Re: Microwave
« on: March 25, 2018, 08:21:26 PM »
I was holding off on suggesting repairing it yourself because units have become less repairable over the years, but I was successful fixing my own microwave. It turned out to be a badly crimped terminal connecting the power lead to the door switch. It had chronically run so hot that it had slowly eroded the connection between the faston (slip-on) contact and the door switch. It's was pretty obvious once you knew where to look, and someone had posted a tip on a forum about my particular model.

So, look up the exact model number and see if some searching yields any clues.

Best of luck,
Jeremy

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