How to replace anodes..

[Threesheets]

I'm a novice - never really done any diy stuff on a boat before. I'm now fixing up my pride and joy and am about to put on replacement anodes on the hull and the propshaft. The teardrop hull anode has a sponge backing strip which make the bolts coming through the hull too short to get a purchase on the nuts. Can I substitute the sponge with a thinner layer of pond liner (which I happen to have in my garage)?
Next I'm wondering how tight to do the propshaft anode. There was some brown gloop on the bolts when I took off the remnants of the old anode - would this be Loctite? Or maybe Sikaflex to stop them vibrating off?
I appreciate all of this is pretty straightforward stuff to you regulars but I'd welcome some guidance here - much obliged.

 

[Pasarell]

Changing Anodes

Welcome to the forum!

Surprised nobody has answered this so I'll give a partial answer that will bring it to the top of the list again.
The neoprene pad for your hull anode is to stop it from rattling against the hull and potentially causing damage. Also insulates it from the copper in your antifouling that will accelerate wastage. There is no reason why you can't use a thinner insulation like pond liner and some people don't use any insulation at all. If your bolts are that short though you might want to think about replacing the studs at some stage in the future.

I don't have a shaft anode so can only say what I've heard from others. Shaft anodes can drop off if the bolts come loose leaving your sterngear unprotected. I've also heard of them rattling when motoring so I expect the gloop you speak of is to stop the bolts from coming loose. Sikaflex I expect but hopefully someone else will come along with direct experience. Whatever you use be careful not to insulate the anode from the shaft with it!

 

[vyv_cox]

The chief reason why shaft anodes come undone is that they were never fully tightened when fitted. Put the new anode on the shaft and tighten the fixing screws. Then take a hammer in each hand, or some other weight, and knock the two halves of the anode together from each side. Retighten the fixing screws. Repeat until you cannot turn the screws any more. You will then not need to use any thread lock or other form of adhesive and the anode will remain in place.

 

[AIDY]

foam backing should compress to give you a similar thickness to a pont liner.... alternatively put some longer studs in.... always a good idea to use loktight or similar on the threads.

 

[VicS]

has Vyv says for bedding the shaft anode in position except that i would suggest a heavy weight in one hand eg a club hammer against one side and whack the other side with another decent sized hammer.

You might like to look at MGDuff's website for general info on cathodic protection with anodes and fitting instructions.

You might also take the opportunity check the bonding of the hull anode to whatever it is fitted to protect.

 

[lydiamight]

After losing a couple of shaft anodes I have found a fool-proof solution. A smear of Loctite on the threads of the bolts and a dab of Silkaflex or something similar over the top of the bolt heads---I actually use bathroom sealant.
When you want to change them them just pick out the sealant with a small screwdriver and give the allen key a sharp whack to release the bolts.
It may be overkill, but it works for me.

 

[Bodach na mara]

You should not need to touch the nuts on the inside of the hull. They stay in place. It is the nuts on the outside that are removed. If they are stuck and the stud rotates, you should be able to get a thin spanner on the square "Washer" that is welded to the stud and bears against the hull. If all else fails, consider fitting new studs but be forewarned that they are a ridiculous price. There was a thread about that a few weeks ago.

The gloop on the other anode studs may be lanolin or grease. I have found either of these to give some protection to the stud/nut assembly and make removal easier and use them on my main anode studs. It is "anhydrous" lanolin that is needed, not the soft stuff used as hand cream. I got mine years ago from Thomas Foulkes in Leytonstone (purveyors of "floating knives that float away rather than sinking. Ideal for nearby boats.") Sadly no longer there I think.

PS, the stud assembly is here http://www.mgduff.co.uk/mgduff-product-catalog/Ancillaries/

A good supplier is ASAP, but many chandlers will sell them as well.