Aluminium Hulls- Yes, No, Maybe?

[Iron Dials]

Hi folks,

A general question for those who know more than I do on the subject, not limited to ribs.

What are the pitfalls, if any, in choosing an aluminium hull?

Are you limited in what anti-fouling you can use?
Damage easily?
Noise?
Lifespan?
Corrosion?
Repairs?

[Pikey Dave]

Great for beaching, more durable, potentially lighter weight. Harder ride, noisier.


Lions led by donkeys

[jwalker]

Also, you mustn't have copper in contact with the aluminium, this probably rules out copper alloys too; cables, coinage, brass or bronze fittings etc.

I don't know whether this is valid for aluminium alloys suitable for boat building but it is certainly the case for most common aluminium alloys, steel in contact with the aluminium and in salt water causes fairly vigorous corrosion.

[MatFromPoland]

Originally Posted by Pikey Dave

potentially lighter weight.

Harder ride, noisier.

I'm not sure about weight ... It depends on thickness of the ALU I think and construction. Mine had ALU solid mast and some back construction from thick ALU (built back). So with petrol 100 l and anchors the total weight of 5,4m ALU RIB is almost 900 kg.

Never have been thinking about "harder ride or noisier"

I think that you be limited to anti foul painting.
It depends on hull type. Mine is powder painting so anti foul is not recommended.

And if you decide to use it you can not use paint having copper (if I remember properly).

Generally GRP hulls usually can have more advanced shapes hard to obtain in ALU hulls (I suppose).

Not sure if you can find stepped ALU hull or air bubble hull like this one mentioned below (AirHull boats .: AirHull :. ??????? ????????? ?????? ??????? ???????? ??????????? ????????):


And in ALU boats usually consoles, jockeys are GRP
In XO boats only hull is ALU but anything else is GRP



I know personally peple taking care about ALU sailboats and commercial boats and they replace anodes and owners have not any problems since more than 20 years.

I wonder why I do not have any anodes in mine boat

[Poly]

Originally Posted by MatFromPoland

I'm not sure about weight ...

at the sub 4m boat size Al is usually significantly lighter - never looked at bigger sizes to do comparisons.

Not sure if you can find stepped ALU hull or air bubble hull like this one

you can make any shape you want, but it will certainly be cheaper to mass produce sophisticated shapes from a mould than welding plates together.

I wonder why I do not have any anodes in mine boat

Unless it is kept afloat then anodes won't really help anyway. The glavanic corrosion issue is presumably less of a worry for trailered Al boat owners who wash and dry strore the boat anyway?

Originally Posted by Pikey Dave

Harder ride

Why? Is it just an "ease" of hull shape (i.e. would a GRP mould of the same hull give the same ride?)

[Pikey Dave]

Originally Posted by Poly

Why? Is it just an "ease" of hull shape (i.e. would a GRP mould of the same hull give the same ride?)

Yup👍 "generally" the ally hulled boats I've been in are slappy. Due to the plated rather than moulded construction. I guess it depends on how much effort the manufacturer is prepared to put into the hull profile. Also it's not unknown for ally hulls to fail on the welds.


Lions led by donkeys

[Poly]

Originally Posted by Pikey Dave

Yup👍 "generally" the ally hulled boats I've been in are slappy. Due to the plated rather than moulded construction. I guess it depends on how much effort the manufacturer is prepared to put into the hull profile.

interesting. I wonder if that is "intentional" i.e. there are other aspects of the hull design they've been compromising on - say to get away with less power, with a particular market in mind.

Also it's not unknown for ally hulls to fail on the welds.

Badly made GRP boats fail too: https://www.gov.uk/maib-reports/hull...rnwall-england

[breezeblock]

if its highfield your thinking about there welding is shocking amongst the worst i have seen thats what sealed the deal with humber i think a fibreglass hull is more durable and easier to repair by mere mortals without a tig welder

[office888]

Originally Posted by breezeblock

if its highfield your thinking about there welding is shocking amongst the worst i have seen thats what sealed the deal with humber i think a fibreglass hull is more durable and easier to repair by mere mortals without a tig welder

Made in China....

AB aluminum welds aren't much better.

[Iron Dials]

Thanks for all the info.

[jyasaki]

Originally Posted by Pikey Dave

Great for beaching, more durable, potentially lighter weight. Harder ride, noisier.

The harder ride part is due to the weight reduction and hull form (form limited by the pressing of the plate into shapes. If a builder will do more welding, any shape is possible.) I (personally) don't think the noise is really a big factor (I can hear my buddy's glass hull bashing waves over the noise my aluminum hull makes.)

You do have to watch anodic protection pretty closely if in the water for extended periods. Don't use a copper based anti-foul without an undercoat. Don't be tempted to use the hull as an electrical return (or earth for you Brits.)

Upside is that dings and scratches don't matter. I bounce off rocks when maneuvering in to go abalone diving pretty often. No worries (well the leg and prop, maybe; not so much the hull.)

Downside is the price of most well-built aluminum hulls.

jky

[GuyC]

Damage Easily - Aluminium boats are more robust than GRP hulls as it is one homogenous material all the way through rather than several relatively fragile layers.

Lifespan - there are 20 year old fast ferries operating for several thousand hours a year still going strong so longevity isn't an issue but then again longevity isn't an issue for GRP.

Noise - aluminium isn't as good an insulator as GRP so it may seem noisier.

Insulation - being a poor insulator, it is possible for void spaces to suffer from condensation. This can lead to corrosion over time.

Corrosion - if designed, built and looked after properly, corrosion will be minimal but not as good as GRP. As others have said, anodes have to be fitted (and working) and you have to make sure you insulate the boat from stray electric current.

Repairs - you can re-weld once before you need to start replacing due to the aluminium going brittle and becoming prone to cracking. Alu is quite amenable to riveted aluminium patches.

Aesthetics - aluminium distorts during welding so the surface won't be fair. Minimising welding to minimise distortion can lead to cracking in welds due to the stresses.

One off builds are probably cheaper in aluminium and you aren't constrained by a mould shape if you want to make modifications during build.

If you are after a robust, one off boat - aluminium otherwise I'd say GRP wins.

[paulbrown22]

I don't have an aluminium RIB, but we do have an aluminium sailing yacht.

I love it as a boat building material, incredibly strong and robust if properly welded up. Our sailing yacht has serious ribs and stringers all across the hull and deck, making it rock solid. We've owned her 12 years now, she's been across the Atlantic and heavily used, and whilst the (original) paint is flaking off in places (it's very hard to make paint stick to aluminium, especially in salt water), she's still as solid as the day she was built. Antifoul (if you use it) needs to be non-copper based, and anodes regularly checked/replaced, but we haven't really done any more structural maintenance than that.

Aluminium is definitely noisier - down below we can hear waves slapping far more than an equivalent GRP yacht - but I guess on an open RIB not as much impact.

I'd absolutely have another aluminium yacht, and would love to find an aluminium RIB!

[MatFromPoland]

Originally Posted by office888

Made in China....

AB aluminum welds aren't much better.

Who else make ALU RIB boats.

I'm not asking for small ultralight like small RIBEYE ALU.

But RIB's greater than 5 m from ALU.
Having better welds than AB or Highfield

Just curious. My next RIB be ALU boat also but hope to have current one to the end of guarantee period which is 5y for hull and PVC tubes

[SixtyNorth]

Robust Boats – Robust Boats

Sea Rib® Aluminium

There must be more.

[MatFromPoland]

Any millpro is out of price range unfortunately.
Military - very good quality but really expensive too expensive for leisure/vacation/family purpose

Robust Boats looks interesting but can not find any info about RIB-s.
Dead rise (hull angle), set-up (for me perfect is current 2 single jockeys in front of big console, big rear bench, covered rear keeping big locker ...

Will keep in mind when change boat after few years.

>>>>>>>>>>>>>>>>>>

These on YT or pictures are more like work-boats.
But have sent email for more details

[GuyC]

Have one built!

Aluminum RIBS (Rigid Inflatable Boat) | Aluminum Boat Plans & Designs by Specmar

[sailrib]

Originally Posted by MatFromPoland

Who else make ALU RIB boats.

I'm not asking for small ultralight like small RIBEYE ALU.

But RIB's greater than 5 m from ALU.
Having better welds than AB or Highfield

Just curious. My next RIB be ALU boat also but hope to have current one to the end of guarantee period which is 5y for hull and PVC tubes

I would not be surprised if you could find a ALU hull manufacture in Gdansk or surrounding areas for a reasonable price. There is certainly a lot of boat building going on in Poland.

[MatFromPoland]

I know a few. One of it makes hulls for other shipyard in Poland who make these boats for Norway. Never looked at welds but in Norway a few of these boats failed. So for me nice or not welds are less important than solid hull. I use boat only during vacation and waiting for this period whole year.

And I could not find any ALU RIB in Poland. HONDA in Poland often has questions about such kind of RIB from water police and they could not find also.

Alimal == robustboats -> looks nice but there are not deep V hull boats.
I'm not expert but my personal preference is deep V hull for Greece and Croatia like 24-25 degree.

I'm not looking now for change. I do not feel such need. But I do like RIB boats and not idea why ALU RIB boats especially.

I do make many km trips to use my boat so weight is important for me. Current boat on trailer (GWV of the trailer is 1300 kg) is optimum for me.

[MatFromPoland]

I have received the offer for 6m robustboat RIB.

https://www.youtube.com/watch?v=4mDBrXH4L4M

It is not deep V type RIB (which I prefer). Of course this type of hull will go on plane easily and can go faster with smaller engine than deep V.

It is different design, material (mine is painted ALU).
When I search internet "ALU RIB" Ribcraft occurs also.

Did they make ALU RIB ?

Generally I do prefer to buy from international company.
I do travel with boat a lot.
Not idea if Highfields subsidiary in Greece, Croatia can help immediately (in any case). Probably will change mine boat before guarantee end and buy another new one.

Maybe super-solid one (but not military - leisure one) be another solution even without subsidiary in other countries. Maybe mine approach is better for cars not boats. But I do not have any Sea in range of 6 hrs of towing boat so mine needs are different than UK people (for example).

But would like to have again ALU RIB as next boat - can not explain why.