Aluminium boats: pros & cons?

Koeketiene

Koeketiene

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While Yanita's up for sale, we are looking at replacements.

Come across a nice one - all the kit, nearly affordable (what boat is?), but aluminium....

I must admit/ I don't know the first thing about aluminium boats. So what are the pros & cons. First thing that comes to mind is elecrtolysis (spelling?), anything else?

TVM
 
Electrolysis
More expensive and less effective anti-fouling (zero copper content)
good strength to weight
difficulty in adding fittings
more expensive to repair damage to the hull
 
Without going to expensive exotic laminates using kevlar, carbon, etc aluminium is generally regarded as the prime construction material for small vessels (by small I mean anything between 0 and 300 foot and assuming not a heavy duty work boat such as a barge or tug). You will, for example, find virtually all high quality yachts beyond small size (say over 50 - 60 foot) are constructed of aluminium.

The vast majority of commercial vessels are now built of aluminium and the only reasons it is not so widely used for recreational vessels is cost of production for production type vessels (ie AWB's, etc) and is more expensive than timber/frp laminates or steel for one off custom builds especially if a high quality finish build (even a well finished steel boat will cost as much as a custom built boat of other materials because of all the extra lining requirments inside it - eg lockers are not self lined in way of the hull as, say, in a plastic hull - and aluminium will be more expensive again if well fitted in that way).

Most of the troubles you hear told about aluminium vessels (such as they dissolve, you have to hang alot of anodes off them, can't berth next to steel boats or piles, etc) are complete rubbish. Older aluminium boats can suffer from being built of inferior alloys resulting in general (not necessarily) corrosion problems.

Our own boat was a professional custom build in steel for us - if doing it again, now some years down the track with construction and material advances, I would go for either aluminium or exotic composites.

John
 
I would generally agree with the above.
If the vessel was built using the correct grade of aluminium in the first place, Was and is propely protected with the correct anodes etc, Has been antifouled with the correct protective layers and it is of sufficient thickness then there should be no real reason to deter you from a aluminuim boat.
Get her well surveyed though by someone that specialises in aluminium before buying.
Joe
 
My son had an aluminium boat for a few years.


Pros

Light compared to steel.

Tough compared to GRP. Aluminium can take a real battering before it breaks. It may dent, but that doesn't stop you getting home safely.

They are different and generate interest wherever you go, if you like that.

Scratches that go through to bare metal are self healing. No emergency paint required like on steel to stop rust weeps.

You will probably come off best if you collide with a plastic boat.

Insurance companies like them. They have very few claims from aluminium boaters.

If properly designed, made and looked after, they last forever. No rot, rust or osmosis.

Cons

Difficult to get paint to stick.

Most designs are multi chined. Round chined metal boats are difficult and expensive to make. Similarly the deck, cockpit and coach-roof all tend not to have too many curves, making them look boxy.

Needs a good insulating lining otherwise noise, temperature and condensation are problematic.

Only expensive and not very effective antifoul can be used.

May be difficult to sell.

Manufacture and repairs require high skills and are expensive.

Wiring and electrical installation must be done especially carefully to avoid electrolysis from stray currents or galvanic corrosion from stray bits of copper.

You need to look after your anodes.
 
Everything McDoom said (we'rrrrre doomed captain mannering, we'rrrre doomed! Sorry. /forums/images/graemlins/blush.gif )

Getting paint to stick to ally is a pain, and scratches arent self healing, they are self corroding. If you need convincing look at an Ovni. You will find that the junction between the paint and the bare ally has tape over it because you can be sure that corrosion and bubbling will start at the interface otherwise.

I was quite attracted to an Ovni until I thought about maintenance. I'm fussy I know, but ho do you deal with a dent in a bare panel for example? And where do you go for electrical kit to be fitted where you know they know what they are doing, stray current wise?

The great thing about GRP is that, bar fire, its almost infinitely repairable. And it can be made as strong as the boatbuilder wants it to be. After all, the structure of F1 cars is largely fibreglass, albeit exotic.
 
Here's a thought - And I second BIRDSEYE's point re paint bubbling and flaking on Alloy fittings (look at any dinghy,wind generator ,etc)...
If you do not paint the Alloy above the water line ,is the bare alloy continually ''greasy'' ,ie if you drag your behind ,or your sails across a bare alloy coachroof ,are you always going to get black streaky marks ?
I have always hankered after an OVNI ,its a series production boat and therefore the niggles and details have by now been worked out .
Incidentally OVNI use a lot of wood battens in the cockpit area ,attached to the bare alloy as an interface between crew and bare metal..
 
Hm - I've been thru the agonising over electrolytic corrosion, paint not sticking, extra anodes etc and like any boat you make compromises. I have an Ovni on order because despite the challenges of doing things with an aluminium boat, the advantages of strength and the sheer quality of construction and finish make them a much better bet than an AWB. Also, they can go anywhere. A donf.
 
Re: If your worried about longevity

don't be. I've sailed many a mile on "Maiden", a boat that is aluminium, has more than a few miles under it's belt, a boat that has suffered from a variable standard of maintenance over the years and while she's got her problems, I can't think of one that is caused by her construction.
 
Yes its a close run decision isnt it? The standard of construction of Ovni is very high and you get the feeling that it is built by cruising men who actually use the boats. The only boat I've sailed on that had a similar style of build was the British Steel Challenge fleet - built at Devonport dockyard..

I'd be a bit less sure about the "go anywhere" bit. An avs in the 115/120 region isnt good.

For all my doubts about the paint etc I might still go Ovni simply for the design and fit out. Plus the UK agent who's a really nice guy.
 
Try looking at www.sailinghols.com The hull being built there is a lot stronger than any plastic one, and cheaper than carbon. Repairs are easy now that many commercial boats are Ali, true you must be carefull with electrics etc. Paint or not to paint will have been deceided for you if you buy second hand anyway. It depends what you want it for. Plastic must be the lowest maintainence. But ali is very strong. Good luck choosing.
 
Re: Aluminium boats: pros & cons?

Thanks one and all for your replies - food for thought.

Guess everyone is a bit hesitant when it comes to things they don't know anything about. Will read up on the subject.

The boat we're looking at is not an Ovni, but a 1979 Huisman 41' (S&S design).
 
[ QUOTE ]
Everything McDoom said (we'rrrrre doomed captain mannering, we'rrrre doomed! Sorry. /forums/images/graemlins/blush.gif )

Getting paint to stick to ally is a pain, and scratches arent self healing, they are self corroding. If you need convincing look at an Ovni. You will find that the junction between the paint and the bare ally has tape over it because you can be sure that corrosion and bubbling will start at the interface otherwise.

I was quite attracted to an Ovni until I thought about maintenance. I'm fussy I know, but ho do you deal with a dent in a bare panel for example? And where do you go for electrical kit to be fitted where you know they know what they are doing, stray current wise?

The great thing about GRP is that, bar fire, its almost infinitely repairable. And it can be made as strong as the boatbuilder wants it to be. After all, the structure of F1 cars is largely fibreglass, albeit exotic.

[/ QUOTE ]

Sorry you are not right about corrosion......

Bare aluminium IS self protecting when exposed to oxygen in air or water. I know - I've had one.

Sure it can corrode due to electrolysis - or indeed a LACK of oxygen on bare surfaces - but otherwise it has greater longevity than GRP when submersed.

And whilst we're at it.....surely FI shells are not GRP but either kevlar or carbon composites?

JOHN
 
We have a 5 year old Ovni that has done the ARC, etc, so has been very well used, but not very well cared for by the previous owner. The paint on an Ovni is applied in many coats, so it takes quite a ding to chip right through to the aluminium. When this does happen, as it has on ours, a very small area of paint around the chip will bubble, where the aluminium oxidises and seals itself. No further action is necessary, although you can obviuosly touch up the paint if you wish. We have not done any repair work to the chips on our boat, as they cause no problem, except for the small bubble patch (which is normally less than 0.5cm around the chip).

The Ovni is very well constructed, using only the highest grade marine aluminium, so the aluminium horror stories you will hear really do not affect this boat. Everything is constructed in house so it all fits together well and is very solid.

This year we used International Trilux antifoul, which seemed no more expensive than other leading brands (obviously you can get cheaper makes), and has so far worked fine. One advantage of the Ovni is that you can easily beach it to scrub it off, no need for an expensive lift out every time. The photo below was taken at the owner's rally last weekend. "Olona", pictured, has not been anitfouled/scrubbed since new (spring 2004), so the owner just beached her to check what was happening.

IMG_4631.JPG



Hope this helps,

Paul
 
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[ QUOTE ]
Everything McDoom said (we'rrrrre doomed captain mannering, we'rrrre doomed! Sorry. /forums/images/graemlins/blush.gif )

Getting paint to stick to ally is a pain, and scratches arent self healing, they are self corroding. If you need convincing look at an Ovni. You will find that the junction between the paint and the bare ally has tape over it because you can be sure that corrosion and bubbling will start at the interface otherwise.

I was quite attracted to an Ovni until I thought about maintenance. I'm fussy I know, but ho do you deal with a dent in a bare panel for example? And where do you go for electrical kit to be fitted where you know they know what they are doing, stray current wise?

The great thing about GRP is that, bar fire, its almost infinitely repairable. And it can be made as strong as the boatbuilder wants it to be. After all, the structure of F1 cars is largely fibreglass, albeit exotic.

[/ QUOTE ]

Sorry you are not right about corrosion......

Bare aluminium IS self protecting when exposed to oxygen in air or water. I know - I've had one.

Sure it can corrode due to electrolysis - or indeed a LACK of oxygen on bare surfaces - but otherwise it has greater longevity than GRP when submersed.

And whilst we're at it.....surely FI shells are not GRP but either kevlar or carbon composites?

JOHN

[/ QUOTE ]

OK, my wording wasnt precise enough! Bare flat ally sheet might fare very well in saltwater, if alloyed with magnesium rather than copper. But painted ally is a different issue in my experience, and thats what I was trying to say. Despite very careful indoor preparation, etching etc, I found that any bubbling round a ding on painted ally rapidly spread underneath the paint. Such bubbling certainly wasnt self limiting.

The comments from the ovni owner were interesting - it would be good to get a bit more detail and maybe the odd photo, because it was the paint issue more than anything that put me off.

I think you would be hard put to prove a longer life for ally than grp, particularly if not carefully maintained. There seem to be very few if any grp hulls that have failed even due to osmosis, and decent modern resins like vinyl and epoxy can make that problem something from the past. But grp isnt subject to dissimilar metal problems, or problems of oxygen starvation which ally is.Nor to simple galvanic corrosion.

There are enthusiasts for every form of boat construction , even concrete. But I'm still convinced that a properly executed grp hull takes some beating.

and if "FI shells are not GRP but either kevlar or carbon composites? " then Benny hulls are not grp but are composites. Just as there are many aluminium alloys there are many forms of what loosely is termed grp or fibreglass. Maybe not very precise, but foam composites incorporating kevlar are often used in boat hulls and most people would still call them glass fibre.

But before this thread descends into semantics, can the Ovni man elabortae for all our benefits?
 
As far as getting paint to stick is concerned, paint sticks to aircraft for decades. You have to use zinc chromate primer which may cost a little more initially. I don't know why this method couldn't be applied to vessels.

It was also mentioned that installing fittings is problematic. A hole saw and a Skill saw are pretty much all you need to work with aluminium. Try installing a seacock or winch on a ferro cement boat!
 
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