Underwater Loc Tite??

[Alan Wheeler]

Right, I get ya.
For me, we haul yearly. So if the zinc has almost gone, but till there, I am happy. If it has all gone, then either I have problem or I need to fit a bigger inc. This year we are booked for a haul in October I think. I have fitted a Galvanic isolator, so I am very keen to see if any change in erosion has taken place.
I am lucky in that we have a lot of fresh water flush through the Marina. So the saltwater is not strong, the water temp is cold and we get very little growth. A year will result in nothing more than slime on the hull.

[fstbttms]

Originally Posted by Alan Wheeler

I am lucky in that we have a lot of fresh water flush through the Marina. So the saltwater is not strong, the water temp is cold and we get very little growth. A year will result in nothing more than slime on the hull.

And I am lucky that our marinas are relatively warm, salty, moderate-to-high fouling environments. I can make a living at what I do.



Wait- did I say I was lucky?

[svcattales]

I bought two "chapstick" like tubes of Loctite to test the bonds before I used it to secure the zinc on my saildrive. I put some blue "248" on a 1/4" bolt and some red "268" on the same size bolt. I let the loctite air cure for several hours on both then submerged the nuts in a bucket of water and screwed in the bolts with locktite. I left the bolts w/nuts in the bucket over night and tested the next day. Next I put the nuts in a vice and unscrewed the bolts with a phillips screw driver. The blue locktite gave moderate resistance at first then released. The red loctite gave higher resistance but gave way before I applied enough force to strip the head. Based on my "amateur hour" lab results I used the red loctite on my zince (sure hope it comes loose next time!).

[hellosailor]

Red loctite is not forever, if there is any contamination (oil in the threads) or it has oxidized (old stock) etc. it can be spun off pretty easily. It sure beats nothing, most of the time, and any time you can't get it to release, you can hit it with a few passes of a torch or flame and it sure will release then.

[arjan]

svcattales
I have been reading your posts on the loctite stick used under water. I have a flex-o-fold prop that needs to come off twice a year because the zincs just keep melting away and I am torn between the red an the blue loctite stick to use on the fasteners. Especially on the prop nut. Have you had any problems getting the bolts out with the red stuff on the threads?

Thanks,
Arjan Bok
R O T K A T

[hellosailor]

Arjan, the folks at LocTite will respond to tech support emails usually the next business day. Personally I haven't used the "stick" materials but the red liquid can b easily broken out with a wrench. If the wrench isn't big enough or the person pushing it isn't strong enough, you hit it with some heat and it breaks down instantly.

Nothing is forever, including LocTite Red.[g]

[imagine2frolic]

I use the red on exhaust manifold studs when replacing them. I have found unless the manifold is extremely hot it always takes some heat to break them loose.

[fstbttms]

Originally Posted by arjan

I have a flex-o-fold prop that needs to come off twice a year because the zincs just keep melting away...

Why do you have to pull the prop to replace zincs? Saildrive?

[arjan]

Originally Posted by fstbttms

Why do you have to pull the prop to replace zincs? Saildrive?

Yes I do have Selva sail drives and the only way to install the zinc is to pull the prop off. Big pain in the a$$, and it is obviously not a real option to haul Rotkat twice a year to replace the zincs so it has to be done underwater. The flex-o-fold props have about 8 nuts and bolts that need loctite.

Arjan

[Zach]

Idea:

Drill out the anodes bolt holes a size larger, slide in sleeve of the same material as the fastener. Switch over to a hex head with a shoulder, or a machine screw with a shoulder so you can tighten it down.

Now if the zinc erodes away under the bolt head, you don't lose your torque on the fastener, and if you step the hole like the original, the zinc won't know the difference.

Also... are these threaded holes blind? How many threads of engagement do you have? Is it possible that the bolts are a few threads to short for good holding?

Zach

[fstbttms]

Originally Posted by arjan

Yes I do have Selva sail drives and the only way to install the zinc is to pull the prop off. Big pain in the a$$, and it is obviously not a real option to haul Rotkat twice a year to replace the zincs so it has to be done underwater.

There is an bolt-on adapter kit for Yanmar saildrives that allows you to use a 2-piece zinc (replacing the single-piece one) where the screws are accessible without pulling the prop. You might try calling Golden State Diesel Marine in Oakland (where I get them) to see if it would work on your saildrives. They'd pay for themselves with the first zinc change.

[arjan]

Originally Posted by Zach

Idea:

Drill out the anodes bolt holes a size larger, slide in sleeve of the same material as the fastener. Switch over to a hex head with a shoulder, or a machine screw with a shoulder so you can tighten it down.

Now if the zinc erodes away under the bolt head, you don't lose your torque on the fastener, and if you step the hole like the original, the zinc won't know the difference.

Also... are these threaded holes blind? How many threads of engagement do you have? Is it possible that the bolts are a few threads to short for good holding?

Zach

Thanks Zack, the problem is not that the zinc gets loose, the whole zinc is gone after about 6 months because the marina where I keep Rotkat must be pretty hot. I didn't have these issues in the previous marina.
Changing the zincs out is no big deal I have dive gear and I'm not afraid to use it ;-)
The reason for the discussion for me was to find the best Loctite solution for the prop nuts and bolts since loosing a prop or even parts of it is not where i want to go.

Arjan

[Davey1000]

Why not buy some Nyloc screws? (the US trademark is "Nylok")

These are screws that have had a slot milled into them that has been filled with some kind of plastic. The plastic deforms as the screw is screwed in and it makes the screw resist vibration. Another type has a "plastic patch" bonded onto the screw.

The main snag is that most shops will look at you as if you are the man from Mars or an escapee from a lunatic asylum when you ask for such items (they have never heard of them!) The same goes for French curves and chimney nuts. Either get the parts by mail order or print out a photograph of the items that you need. Without the photograph they will think you are a lunatic as you just cannot get the right staff anymore.

Good luck!

[Jsol]

Another solution is a product called Vibra-Tite. I have a propnut zinc and this comes on the threads of the screw. I found out what product they used and bought some. I also use this for my set screws in my cutless bearing. Works great. I used VC-3.
http://www.vibra-tite.com/

Hope this helps...

[hellosailor]

"The main snag is that most shops ...have never heard of [nylok]"

Well, five long years ago the OP posted the original question from Florida. Where every hardware store, including the chains, has Nyloks on the shelf next to the other threaded hardware.

Maybe you're out in the boonies, way out in the boonies, or there's a translation problem, but Nylok is commonly used in machinery that goes around the globe. Perhaps, like Perspex, it is simply unheard of by the original brand name outside of the original location.

If someone in the hardware store gave me a crooked stare when I said "Nylok?" I'd ask him how come he left McDonalds. And whether they were holding his old job open for him.