Alluminum boats and corrosion

[James448]

Hi I am new to the forum and I’m currently doing research about what sort of boat to go blue water crusing with. I am a welder by trade so I’m leaning towards steel or alluminum as supposed to grp. I’m very interested in a Van de Stadt designs preferably alluminum boat but I worry about corrosion Issues as my price range means I’m looking at boats that are 15+ years old. Any advice would be greatly appreciated

 

[vyv_cox]

Owners of aluminium boats need to be very careful of galvanic corrosion. Almost any other metal (except zinc) will be more noble than aluminium, with the result that if the couple is wet there will be corrosion of the hull. The good news is that it will be visible in the vast majority of cases, around the fitting or whatever has caused it. A detailed inspection will usually tell you of any problems.
Stainless bolts and fittings are usually isolated from the aluminium with plastic washers and sleeves.
Many owners hang zinc anodes overboard on stainless steel wires whenever the yacht is berthed.
I believe the Ovni owners website has a very useful forum about corrosion but you need to register to see it.

 

[PhilipH]

I have an OVNI 395 built in 2006 and owned from new. Sailed 60,000nm and corrosion is a minor irritant provided you take care. As Vyv Cox says, fit a galvanic isolator and hang extra anodes (We have two connected by large crocodile clips to s/s bolts tapped into spots at the bow and in a cockpit cave). The plastic washers for bolts such locker lid fastenings do not work very well but zinc chromate paste does and even better is Tef-gel. After that live with some bubbling of paint or preferably minimise the painted surfaces. It is just something to add to the maintenance list and if you have the benefit of unpainted top sides then that saves all that time on polishing ....

 

[James448]

So I understand that galvanic corrosion is the enemy. If you are able to isolate the different materials then this should be reduced. In areas such as chain plates of shrouds or where cleats are mounted then this must be a problem. Hanging extra zinc annodes overboard Aswell as the usual that are fitted is this to reduce corrosion on the hull?
Are rudders usually fabricated out of alluminum this seems it could be a problem area especially with a stainless shaft on the rudder and also prop shaft ?
Does any one have a idea of up to date literature I could spend some time reading
Thanks James

 

[Tradewinds]

I think it might be helpful that you PM Noelex who is on his 2nd aluminium yacht and is a liveaboard.

I suspect what he doesn't know about aluminium boats and corrosion could be written on a postage stamp (or even a grain of rice!).

 

[PhilipH]

So I understand that galvanic corrosion is the enemy. If you are able to isolate the different materials then this should be reduced. In areas such as chain plates of shrouds or where cleats are mounted then this must be a problem. Hanging extra zinc annodes overboard Aswell as the usual that are fitted is this to reduce corrosion on the hull?
Are rudders usually fabricated out of alluminum this seems it could be a problem area especially with a stainless shaft on the rudder and also prop shaft ?
Does any one have a idea of up to date literature I could spend some time reading
Thanks James

Actually no to first two comments. On most alu boats the shrouds are attached to welded fittings rather than traditional bolted chain plates. Cleats are also welded so there may be a bit of paint flake but that is all - and you can hang the boat from the Cleats (Well, a bit). The extra hanging anodes actually help the fixed anodes and reduce their degradation. Rudder is not a problem - the bearings are acetol/delrin. We have a maxprop with the cone anode at the end of the shaft and this works hard but the hanging anodes make a contribution. Sorry no literature but the manufacturers and agents usually will answer questions. Hope this helps. I would not have anything other than aluminium and I have had grp boats.

 

[npf1]

If you're interest in aluminum boats, may I suggest you join https://www.morganscloud.com - it's a very useful website with many, many articles on alu boat ownership..

 

[Chris_F]

If the aluminum becomes exposed it will develop a white powder on the surface of the metal, this is the corrosion. It can lift paint off in the same way rust does it. I used a heavy corrosion inhibitor https://www.boatid.com/crc/marine-corrosion-inhibitor-mpn-06026.html on exposed metal parts on my boat and for now it holds up pretty well.

Found this article about Protection against Corrosion of Aluminum Alloy in Marine Environment. You guys may want to read it: https://www.hindawi.com/journals/ijc/2016/4891803/

 

[TQA]

Here is a cautionary tale on the risks associated with buying an old aluminium boat. A German girl bought a cheap aluminium boat in Panama and then discovered she had bought a colander. After many trials and tribulations she got it fixed and went sailing. Here is a link to the video no 30 when the welder arrives.

 

[doug748]

Any advice I have on the issue is not worth a bobbin. Though I have seen all manner of inexpensive metal boats made serviceable with the application of specialist time and effort.
I also was thinking about the whitespot video but rather as an example of how, with your skills, you might fettle a cheap boat for almost no money. Sounds ideal.

 

[James448]

Looks very interesting , I notice that there is a few to join the site. Do you think it is worth it ?

 

[James448]

That’s all good information thank you. Can I ask where abouts you are based ??

 

[James448]

Shame for the lady looks like a disaster ,, hopefully a good survey and careful examination of the boat will keep me well away from any issues like that.

 

[Kukri]

I think perhaps the oldest aluminium yacht - the 1948 Laurent Giles offshore racer "GULVAIN", snapped a few weeks ago at Suffolk Yacht Harbour:

 

[Tranona]

You don't say what your budget is likely to be or whether you are in the market now, but it might be instructive to look at an Italian built Giles design 60' aluminium hull ketch for sale in Poole. Looks a bit tired but from what I could see the hull is excellent.

Details on www.preciousmarine.co.uk This seems to be a listing agency rather than a conventional broker but there is a detailed description and photos. Boat is very accessible in the water at Cobbs Quay.

Unusual to see a boat of this style and quality in the UK so probably well worth a look.

 

[James448]

I am currently trying to investigate the problems that a alluminum boat may have with corrosion. I will be in the market over them next year or so. I think a budget of 80,000 plus or minus. Looking at boats around 13m.

 

[Kukri]

I am currently trying to investigate the problems that a alluminum boat may have with corrosion. I will be in the market over them next year or so. I think a budget of 80,000 plus or minus. Looking at boats around 13m.

Here's a nice one in your price range. I can recommend the design.

http://www.dbyboatsales.com.au/listing/camper-and-nicholson-55

 

[Tranona]

I am currently trying to investigate the problems that a alluminum boat may have with corrosion. I will be in the market over them next year or so. I think a budget of 80,000 plus or minus. Looking at boats around 13m.

You will find your choice extremely limited if not non existent in that price range as so few boats are actually built in the material and particularly in the smaller sizes (sub 13m). You will find older Ovnis, usually in France, but not 13m.

If your budget is for a ready to go boat then realistically you need to be looking at max £60k for purchase of the boat. Inevitably whatever boat you find will be old but you will likely find more steel boats of that size in that price range simply because most will have significant long term maintenance issues. You can, however find good ferro boats from time to time.

For maximum choice (and arguably best long term value) GRP is still the best bet. There are many very good designs in the 11-13m size range that can be bought in your price range.

 

[Heckler]

Any advice I have on the issue is not worth a bobbin. Though I have seen all manner of inexpensive metal boats made serviceable with the application of specialist time and effort.
I also was thinking about the whitespot video but rather as an example of how, with your skills, you might fettle a cheap boat for almost no money. Sounds ideal.

Watched all her vids, impressed but! An aging pony tailed German wielding a stick welder? Hmm.

 

[noelex]

James, you are doing the right thing learning as much as you can about aluminium boats.

No boatbuilding material is perfect but aluminium has some great properties and is the best material other than the expense, but aluminium boats need to be well constructed and the owners need to know what they are doing. Wiring mistakes, or even the wrong antifouling can have serious consequences.

When buying an aluminium boat first check it made of a suitable grade (or grades) of aluminium. It is not unusual to see unsuitable grades used. There are significant differences.

Next it has to be correctly welded. You should be in a great position to identify the weld quality. Very few boatyards can weld aluminium well.

The yacht has to well designed by a designer familiar with aluminium.

Finally, the electrical installation has to well done and if any changes have been made by owners they have to be done correctly. Some electrical practices that normal on a fibreglass boat can rapidly cause problems on an aluminium boat. Even marine professionals can make mistakes if they are not familiar with the material.

If the boat has been well constructed and the owners know what they doing, aluminium is a wonderful boat building material and won’t give you any problems.

Good luck with your search.