i can't get to my boat for a few days - where the transmission shafts a standard size of 1 inch? i'm 1986 hull 99 and i looked in the manual and can't find a diameter for it. i want to get an magnesium anode for it, before i launch.
thanks
becki kain
Prop shaft = 1"
becki : ........ and if it original it's bronze.
A thought
its not. the original, which was bent, is in my dock box
thanks!
Ha! Ballast? A persuader? Dock box theft deterrent? Nunchuck? :donno:
-k
well, i am in detroit....
do i need to use specifically "Tef-Gel electrical isolation compound" or is there a home depot replacement? I'm not certain I can get it in time, to launch, to get it.
Becki,
If the Tef Gel is related to fitting your zinc, I've never applied anything to my zincs or shaft before i put them on. I simply clean up the shaft with a scotchbrite pad or emery cloth where the zinc will be mounted to ensure a good electrical contact. I use magnesium "zincs" in the fresh water of Georgian Bay. If you've already bought a zinc "zinc", it will be fine for the year. Magnesium is better is fresh water, zinc is better in salt.
Good luck with your launch!
Quote from: anaisdog on June 06, 2018, 06:07:14 AM
do i need to use specifically "Tef-Gel electrical isolation compound" or is there a home depot replacement? I'm not certain I can get it in time, to launch, to get it.
An anode MUST have great (not "good") electrical contact to be most effective. We're talking millivolts difference in electrical potential between different metals that causes galvanic corrosion.
So, JTSO IIWMB, IW (others' mileage may vary)
1) Clean both surfaces well, w/ a wire brush on a drill for the concave of the anode (to bright metal), wet sand the spot on the shaft w/ say 800 grit.
2) Use SuperLube gel between them (more available than T-Gel).*** Or, possibly copper-based never seize between them, but SuperLube is a USCG mandated carry-aboard lubricant/protectant (found in any good hardware store) so everyone has that in their repertoire anyway.
Understand that, if the shaft isn't electrically connected to anything else the anode doesn't protect against galvanic corrosion due to dockside and boat electrical leakage (i.e., it must have electrical continuity to your 12v negative buss.) It also doesn't protect the strut (due to the rubber cutlass bearing.) So if you want to protect it, add an anode there -- there's recent posts (in last year) about doing that.
The shaft anode should be *close to* the strut, about 6", not in the middle of the span.
*** Just to clarify you aren't trying to "electrically isolate" the metals as T-Gel implies, you are preventing future corrosion between them. The two surfaces cut thru the thin film of gel laid down and make electrical contact, and leave any open space with gel to protect the surfaces.
-k
Ken-Perhaps I am not reading you clearly, but I personally, wouldn't put SurperLube, Tifgel or anything between the zinc collar and the shaft itself, preferring unimpeded metal-to-metal contact. I can see where you could/would put it on the bolts/nuts that attached the collar and hold it tight to the shaft (and in the case of a prop, the bolts that attach anode to the end of the prop) but not to the mating surfaces between the metal that is to be protected and the sacrificial anode. Attached is a MaineSail discussion on this subject.
https://forums.sailboatowners.com/index.php?threads/anode-installation-best-practices.175835/
Question Noah
What's the difference in this application vs using T-gel on an electrical installation? e.g., a terminal on a post? What's your reasoning to use it there but not here?
-k
Added: check out the Tef-Gel product instructions and uses on the website, might be surprised.
Note that SuperLube is also the same, ptfe suspension, but I can't attest to the precise vehicle used in each product, just the HUGE cost difference.
I have never advocated "using it on a terminal nor a post", so I am not going to debate that one. I believe it is pretty standard best practices to leave the anode contact to protecting metal mating surface, free of any coatings. I do use Tifgel to isolate fasteners into dissimilar metals, such as stainless steel bolts into an aluminum spar.
Then read the usage instructions on Tef-Gel, they speak to exactly this situation of "mating surfaces".
Many have advocated using it on electrical connections and it's absolutely proper.
Interesting that Mainesail, when describing "best practice " for fitting a shaft or prop zinc, mentions using Tef gel on the bolts/fasterners, but doesn't say use it on the mating surfaces, such as on the shaft or prop themselves...
I agree. So did you see the instructions? tef-gel.com
I use the common sense test, step back and look at what is going on.
1. The electrical connection is what's important.
2. The connection made thru the two faces is still an electrical connection like as made with a terminal on a post or on a terminal strip. J and others have no issue using TG on an electrical connection. The fact is, the Teflon gets squeezed out of the "connection" but protects everything adjacent and fills any microvoids that occur and prevents future corrosion. Same thing with the anode connection.
3. RC is slathering the bolts, and the TG remains there because there's space between the bolt thread and hole -- it isn't a pressure fit. You could use anything. Petroleum jelly, fill with epoxy and drill it out, bubble gum, whatever -- just so long as it isolates the two surfaces.
4. with the contact surfaces, that's different -- you want the TG to squish out and leave fresh metal-to-metal contact.
5. 6 or 7 square inches of contact area on the shaft is unnecessary to make the electrical connection. Not when the electrical connection to the negative buss is the area of a ring terminal. My point being, even if there is a micro area (or even HALF of) where the faces meet that doesn't make contact due to TG, there's STILL WAY MORE than necessary. And the remaining TG will fill microvoids and be a barrier to prevent weeping of corrosion into the interior faces of the shaft/anode and prevent deterioration of the electrical contact. Same as it does on a circuit terminal strip or buss.
-k
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
J
Here's an exchange with SLube about that. I agree that, given all other equal, the ptfe isn't needed in this application (no lubrication necessary) if one carried both types. A prior email said that they are basically the same, minus the ptfe.
Ken,
Our part number 91003 is our super Lube® Silicone Dielectric Grease and part number 82003 is our Anti-Corrosion Gel. I have listed some differences.
The grease is much thicker than the gel.
The grease uses silicone oil as its base oil, whereas the gel uses a blend of mineral oil and PAO oil.
There is a higher concentration of anti-corrosion additives in the gel.
The gel has been tested and approved by Thermo-King for their electrical connectors on refrigerated trailers to reduce road salt corrosion and fretting. (see attached link)
http://www.super-lube.com/files/pdfs/Connector_Gel.pdf
http://www.super-lube.com/files/pdfs/Technical_Data_Sheet_Engine_Treatment_w_PTFE.pdf
Use our Super Lube® Engine Treatment, 20320 at a ratio of 4 to 1.
For a standard engine oil and filter change which requires 5 quarts of oil, use 4 quarts of the recommended motor oil and 1 quart of Super Lube® Engine Treatment.
I have attached a few links for your review.
http://www.super-lube.com/files/pdfs/Technical_Data_Sheet_Silicone_Dielectric_Grease.pdf
http://www.super-lube.com/files/pdfs/Technical_Data_Sheet_Anti-Corrosion_&_Connector_Gel.pdf
http://www.super-lube.com/files/pdfs/Technical_Data_Sheet_Silicone_Lubricating_Grease.pd
http://www.super-lube.com/files/pdfs/engine_treatment_technical_bulletin.pdf
Regards,
Kevin Wall
Operations Manager
I wonder whether the grease is better lasting underwater? Although, as I tried to explain (probably not well) I think it may be moot because the anti-corrosiveness really resides in the minute voids and neither should get "washed away" out of there. The grease might work better on the "bolt application" as RC describes. dunno. :donno: :donno:
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
Jeremy
I had discussed the multi-purpose synthetic in an earlier email w/ them.
However, the datasheet omission was my fault.
His datasheet links were dead, so I copied over the new URLs. But I mixed up the silicone with the synthetic . MEA CULPA.
http://www.super-lube.com/files/pdfs/Technical_Data_Sheet_Multi_Purpose_Grease.pdf
(http://www.super-lube.com/images/synthetic-grease-3oz-tube.jpg)
-ken
Jeremy:
from another sailor....
I use Ox-Gard anti-oxidant compound which is electrically conductive (formulated with zinc) on both anode and shaft contact surfaces. To isolate the stainless screws as much as possible from the anode, I place a plastic washer between the spring washer (under the head of the screw) and the anode, and put a few wraps of PTFE plumbing tape over the length of the screw before inserting the screws and tightening. (Both Ox-Gard and PTFE tape are available at Home Depot, and the plastic washers usually come with the anode)[/i]
I have never used GB Ox-Guard, have you?
Any thoughts?
-ken
(http://www.gardnerbender.com/~/media/inriver/355274-37344.jpg)
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 don't 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.
Thanks Jeremy.
I understand all you are saying -- the point of current flow if the whole thing is submerged is key.
What I don't really understand (not a metallurgical engineer) what's the interaction between the anode and s/s bolts/nuts?
I would **think** it would be similar to having good contact between the s/s shaft and the anode? How are the bolts different than the shaft? i.e., what's the galvanic transfer going on (if they are not completely isolated from the anode.) And, I guess. what's the difference anyway? -- if the anode gets that bad -- screw the bolts -- I'm gonna cut them in half w/ an angle grinder.)
-k