Prop anode “ thread locker “?

Does anyone know what this white waxy paste is stuffed up the 60mm hex anode on the prop bolt ?
Presume due to anti-clockwise rotation ( the wheels spin outwards ) it’s placed to stop the stud unwinding?

You might see it better on this vid ?
https://www.youtube.com/shorts/6jN08Zg2R38


The yard deal in mostly super yachts with normally a 600T lift .The 30 Ton crane is for small fry .So have they or are they bringing something from SY experience?

Here - The yard .

The prop nuts are nibril or similar and the anode bolts going in S Steel .
When I used to DIY the annual lift in France we used a blue thread lock 242 .
Thread lock works , sets due to lack of oxygen in the tightening threads .It’s the lack of air that sets it .
I suspect water will find it way through from the mating surface the other end , where the hex fits the prop bolt .That obviously thins down as the anode wears away anyhow.

Transom anode .
Yes I have previously used ones with a screw in cap over the bolt hole space in Fr .
They actually could do 2 seasons as they wear slowly, but I prefer a fresh set annually considering what they protect the MAN s .
There’s not an issue undoing them as the zinc and SSteel bolt are touching the through the hull threaded bit anyhow so no corrosion, tightness to overcome .They obviously never loosen as not spinning .

Was hoping the white paste was sone sort of anti loosen stuff .

On the Itama owners FB page there is quite a few who loose the port prop anode .Recently a guy crossed Rome to Magdalena islands and his port anodes disappeared. A 46 with the exact same engines the V8 800 s as yours .
He took it easy for eco reasons his vid , shows 24/25 knots so it’s not as if he’s caned it at 34 knots full tanks etc and pushed what ever his recently yard used .
He’s claiming against the yard and indeed they are sending a new anode FWIW .

I have a hex socket and every few days ( when no white paste was placed ) just snorkel in and nip it up the bolt is long sat 40 or 50 mm anyhow so to loose it that’s a lot of unwind turns , but a 4/5 hr run maybe ?

I have just completed 300 + miles , the longest stint 70 at 27/28 knots and it’s still solid .
They have been on about 6 weeks .I guess as they thin down ……..?

Actually risking being of accused of over thinking this?
Wont the white stuff squirted in fill the internal hex of the bolt head , thus if the white stuff sets somewhat adheres to the hole inside the anode how can the bolt unscrew itself ?

Even spinning as relative to one and other the bolt , the white stuff and anode are spinning at the same rpm .The bolt is locked through its hex internal head if you see what I mean .


For the bolt to undo it’s gotta rotate anti-clockwise faster than the rest .The rest being it’s prop bolt shown above , but the white paste is gripping it to the anode .The anodes 6 flats , it’s hex lock onto the prop bolt so that never spins it can’t .Anode + bolt + props turn at the same rpm .


Anyhow 6 weeks in , so early days .
It’s just once the conventional thread lock the blue 242 or what ever looses it so to speak , which it seems to do regularly then without the white paste there’s nothing stopping the bolt spinning out .

Starting to make sense . Now the internal hex of the anode bolt is filled .
https://www.3m.com/3M/en_US/p/d/b40066996/

They will be doing the annual next time , so it’s there problem getting it out .

I did 5 DIY annuals and we used ( went through the range ) of locktight thread loc .Even went to the rouble to dry the inside of the prop bolt incase moisture contamination weakened the thread loc stuff .
I’ve lost it twice in the first years .
As said just resigned to a occasional snorkel nip up .
Until moving it Italy and the marina yard do not allow DIY ers , they do it all .
I didn’t ask for the white paste ( sika what ever 5200 ? ) or mention I had previously had trouble with the port / left one loosening …..they did it on there own .
The lads on a Friday lunchtime frequent the marina bar and refer to us a “Mr + Mrs Itama “ I get the impression they like the boat .

We do cruise around just under 30 knots and the boats a mid engined with the props shoved as far back as possible to get the lowest shaft angle for efficiency and speed purposes.The V12 MAN powered 90 s versions can get to 40 knots .

Maybe others , MapishM s point do loose them on the anti-clockwise wheel but it’s not recoded .I don’t think it’s only an Itama thingy unless it’s shaft angle , speed and open prop blade related .

If you think about it as the anode basically shrinks from all its surfaces as it wears it looses it tight fit of the hex sides and it’s internal face .
That face was tightening up flush when the anode was fitted .

If the shaft angle is say high ish Guess 12 degrees or greater .Say a rear engined boat not so performance orientated , then even though it’s loosened a bit by erosion it kinda jams in the water wake as it’s pushed back jamming the bolt stopping it rotating .

Where as if the shaft angle is below a certain inclination say 6 or 8 degrees the anode is slipstreamed so wobbles about as it shrinks the bolt gets vibrated and once it’s thread loc ( what ever number used I have used 3 ) is broken the bolt due to the anti-clockwise ness eventually spins it’s self out .

@MapishM it’s not yard incompetence and from me and my engineering graduates mates DIY ing the annual in France ….incompetency.

How ever in the absence of other boats loosing there anti-clockwise prop anode commonly, ie only Itama then that’s ( shaft angle ) the only difference .

Looks a pretty universal issue .
A lot of stuff here theses guys and myself have coincided , the bolt wobble .

http://www.tugnuts.com/viewtopic.php?f=2&t=14397&sid=413ea9aa1a3ee6c8c5b98fb58ab28b28

Also read somewhere a guy suggesting the SSteel bolt accelerates galvanic corrosion of the zinc around the bolt .So he recommended nylon bolts .
Any one heard of nylon anode bolts ?

I mean I am happy with the 5200 method stuffed up as said 300 miles and counting it’s still tight .

I post theses pic based on my experience with a 86 Testarossa back in the day .


Borriani single wheel nuts .
Exactly the same issue ……well could be in theory but Ferrari reverse threaded one side the left ,so in forward motion ALL four always tightened as you went forwards.

You don’t want to pull up to lights and find a wheel ( one of yours ) passing you !

So based on that why not reverse thread the port anti clockwise prop nut ? Only the anode retaining hole not the lock bolted main ( prop to shaft ) bit .

“Righty tightly , lefty loosely”

Idea with none stretch single bolted wheels is to sync the tightening rotation with wheel rotation.

So going Fwds in the single nut wheel on a car the left wheels are turning anti clock wise and the bolt is experiencing forces to start to undo it .As the pic shows they were chromed single castings with very little stretch .Aside unlike a zinc the mag alloys did not shrink .In fact the insert was made of steel .So by choosing a LHD thread on the L ie tightens up to the L , those LHS wheel bolts tightened in motion , or turned around lost the tendency to loosen .
By 88 Ferrari dropped the single bolt and went conventional 5. Stud with as said by CR stretch bolts , with friction shoulders all RHS threaded .

Having said this America was a huge market for the Testarossa ( Miami vice free marketing , Enzo gifted Don Johnson a personal one BtW ). They did start to incur wheel losses but mainly in the US .Even with LH threads etc .They put this down to the variable torque used with a lead mallet and massive spanner .You couldn’t quantify how tight you did them up .

With conventional studs you can use a torque wrench and quantify the bolt tightening so end of problem……which was openness to US lawsuits .

Back on to boats the Conventional “ righty tightly - lefty loosely “ works the same on anode bolts so it’s always the left wheel that turns anti-clockwise so does the bolt .
As we have figured out and others in the link I gave it’s unsolvable problem because the anodes shrink then wobble then render thread loc or a star washer ineffective then the bolt starts to gradually unwind with the anode rattling away .

Even what my yard have done stuff sika something in isn’t full proof because if you think about it , as the anode shrinks it will detach from the internal aspect of the hole .Stay glued to the anode hex Allen style head bolt .So the whole white thing may spin anti clockwise as the bolt comes out .

A lefty thread in the port anode thread is to me an obvious solution like Ferrari reversing the thread on one side so the gen Fwds motion tends not to loosen them .

Tbh I was surprised spring 2015 the first lift in my tenure both prop nut anodes were identical threaded .
It’s only from a loosing anode pov got to last to Oct then the boat hibernates .

I agree with your comments on shaft anodes , they shrink loose and slip down over the cut less bearing water inlets and I believe may contribute to vibrations .Aside a bit deeper and more diff to causally snorkel fix .

There’s no evidence to date of any adverse corrosion on the props or shafts .So even in reality as they shrink from Nov to the end of May in the marina and rattle around they still seem to protect the stern gear I guess the bolt loose as it is keeps the connection .I would be more concerned if they did NOT erode away with time .

I am coming round to the conclusion on my boat the left prop that turns anti-clockwise with a RH ( righty tightly - lefty loosely ) threaded anode bolt has to managed .
Its the inevitable rattle from a eroding anode that defeats the thread loc that seems the consensus.


As i said in opening post let’s not loose sight of the poor guy in the I 46 who’s port anode was lost within weeks after a 5/6 hr trip .
Can’t see yards not applying a thread loc compound .

Pleased you don’t appear to have the same problem with you left prop anode .