Changing Annodes?

Whitelighter

Whitelighter

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I bought my boat new in February this year and have had her aon a swinging mooring since March 1st. I have booked in a lift and scrub for mid June at sparkes, and have been wondering about changing the annodes. I have purchased a new set (7 of them which suprised me) but I dont know how easy they are to change, or even if it will be neccessary.

My question is two fold: would you expect annodes to need changing in 12 weeks on a tidal mooring away from the marina and b) is it easy to tell when an annode needs changing?

The boat is a sterndrive with a Mercruiser Bravo 3 leg
 
If you are not on shore power and have no other boats within a few metres of you, you wont have to change your annodes for a long time if ever. If you ever did need to, they are easy to change, just undo the nuts, remove the old annode, clean and grease up the terminals to ensure a good connection, stick on the new one and bolt it up again. Much like changing a battery really, as it is important to ensure a good electrical connection.
 
Forget it. Leave boat in till late in the year. Might need a scrub then. Look at anodes, there either wearing away or not. If not wearing at all, check whether they are working? Should last at least a year. Depends very much on area.
 
Anodes are easy to check - they should be visibly eroded - if the they are 50% or more eroded then change them.

7 anodes sound right for a twin installation (not sure where the odd one goes though - Bowthruster mebe), but too many for single.

Also - mid June probably tad early for summer scrub - made same mistake last year.
 
Hmm - why to early? You reckon it will get furry again befor October? It is a single drive, but the mercruiser agent (and Essex Boatyards for that matter) said 7 was on account of it having Stainless Steel props??????
 
I have Volvo 290 leg with SS props (single) and have a Prop ring anode, 2 x small triangle anodes and a big bar anode - the ring anode disolves like sugar but the others would probably last all season.

I am on east coast - first year launched late feb, out mid June for summer scrub - very little fouling and the anodes (incl sugar ring) still had zinc left - by end August though top speed was reduced due to fouling - think most growth occurs June / July / August hence now do summer scrub mid July.
 
Jez,

I am surprised at 7 - my count gets 6 for the new BIII; horseshoe one at the front of the drive above cavitation plate, 2 discs on the underside of teh cavitation plate at rear, one on each ram and one on the propshaft.

The reason you have so many (and you have a Mercathode or 2 as well!) is because they do get used up quickly - the twin stainless props not helping at all.

It is important that you establish the rate at which each is being used up and keep a written log of them to enable you to optimise changes with other maintenance items. You can change them all in the water but finding a really calm spot always seems a problem!

As a quick check you should raise the leg (engine off of course) to the trail position and feel under the cavitation plate for the twin discs at the back. Should feel slightly rough and a bit pitted but not significantly erroded - they start life flush with the cav plate. Seperately reach down to the ones on the rams and compare them with the new units.

My guess would be that you will feel confident to leave the lift and scrub until late June /the begining of July and that you will only need to change the pair of ram anodes at that time. I have no experience of the relative rates of wear on the new prop shaft anode at all so can't comment on that.

I have an older drive and change 3 of mine (rams and 1 cav plate) every 4 months and the big horseshoe one every 6 months.

As the water warms up stick on a mask one day when in clear water and have a good look.

Duncan
 
Agree with you on that one it is 6 anodes on the later B3 drives.
I would recommend them looked or changed now. The ram ones are a pain because there is not much meat on the anode were the bolt goes through and regularly start to come loose as they start to erode.
Atleast you know you gonna have fresh protection for the summer. Iwouldnt be a million miles out to say 3-4 anode changes a year is about right well here on the south coast any way.
Part of the service if you are having one done is to check the mercathode output so best done before the boat comes out. Then get the engineers back to service drive.
 
Good point - no mention of the boat having been out yet and surely it will be approaching 50 hrs and an engine allignment check etc

Bit more than a lift and scrub - but good to do at the same time!
 
[ QUOTE ]
Iwouldnt be a million miles out to say 3-4 anode changes a year is about right well here on the south coast any way.
.

[/ QUOTE ] Is this just for mercruiser outdrives or are you talking volvos aswell?
 
People don't often know that the most wear on an anode is when the boat is at its mooring! almost no wear when the boat is being used! Marina moorings are the worst because of all the electricity about including 12v that could be eroding your anodes from the boat moored next to you!
If you are on a swinging mooring, I don't think that you will experience much wear at all! just raise your leg and look at the the anodes, if they are very pitted and do not resemble the shape of the new one which you have then change them! if it looks ok, then leave it. I only change mine once a year, and I keep my boat in a large marina with loads of electrolosis about!

Barry
 
I still think Barry is right. You only lose metal off your annodes when there's somewhere else for it to go, usually onto someone elses boat (That's why its called an annode, and the place it ends up is the cathode). They dont just dissolve in water. If you're on a swinging mooring, and not on shore power the annodes will not need replacing. Finally, if you've got stern drives, you wouldn't need the boat out of the water anyway, just lift the legs and sit in a dinghy.

If you anti fouled your boat correctly it wont need a scrub yet either. Best leave it till July, anchor on a nice calm sandy beach somewhere and put on a mask and flippers. There will only be a bit of slime and it will wipe off easily with a nylon scourer pad or similar. Barnacles on the stern gear and props can be more of a problem, and will really slow you down, but if you've got stern drives you can lift them to clean with a scraper.

The cost of a lift seems unneccesary to me.
 
Fully tilting a BIII is unlikely to get more than a bit of 1 prop out of the water, but I agree that 5 out of 6 of the anodes could be replaced reasonably easily with the boat in the water, the horseshoe can be a pain though.

I agree it needs something to head to, but it doesn't need an electrical current. Steel mooring chains, piles, etc as well as the drives own props will all do the job.

However, I find it somewhat bizzare that peps are arguing with what does happen in that location with that equipement.

Re costs no one is suggesting that the boat be lifted to replace the anodes without checking it's necessary. SOme are suggesting than on checking it may well be found that they do need replacing (although the latest additional anodes may have improved things a bit) others are suggesting that they will last a year. Let's see - no point in debating.

As importantly there will be 50 hr service requirements that require the boat lifted as well.
 
Again with you on this one Duncan we could go back to our mercruiser-volvo corrosion postings and start this all over again. The fact is here it is a Bravo 3 regardless of the length of time in the water or the location, wether it is hooked to shorepower or not there is an awarness of corrosion issues on this sterndrive product. Speak to any mercruiser dealer they may stumble but if you say you have heard a lot about this topic they will openly speak to you. My advice check/change the anodes!!!
 
I suspect your understanding of what anodes to is flawed. There does not have to be an electrical current running through the anodes (and cathodes) as in the sort of thing you may have done in school.

Anodes on boats are sacrificial, and are designed to cope with the differences in nobility between different underwater metal parts which could become corroded if not protected. An anode on a boat on a swinging mooring miles away from any electrical activity will still need replacing regularly. If anyone has anodes, and keep their boat in water, and the anodes don't need replacing, then they have a problem. How long it takes the anodes to corrode can vary, and some might get a year or more out of them, but they will still need replacing. Guaranteed
 
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