Advantages of Fibreglass / concrete / steel / aluminium

DAKA

DAKA

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Just thinking in general about the different types of boat hulls and wondered what the advantages were of each

Fibreglass- last for ? 100 years ?, cheap to mass produce, looks as new for years very light but not practical for one off

Concrete -really cheap for self build but only lasts ? 30 years ? so quick depreciation

Steel-easy self build , last for ? 40 years ? high maintenance

Aluminium - easy self build light but cost a lot lasts ? 60 ? years

Why do the Dutch prefer steel ? they mass produce , is it because they only occasionally see salt water compared with UK boats ? Atlantic are made from fibreglass but their hulls are made in England :confused:
 
DAKA said:
Just thinking in general about the different types of boat hulls and wondered what the advantages were of each

Fibreglass- last for ? 100 years ?, cheap to mass produce, looks as new for years very light but not practical for one off

Concrete -really cheap for self build but only lasts ? 30 years ? so quick depreciation

Steel-easy self build , last for ? 40 years ? high maintenance

Aluminium - easy self build light but cost a lot lasts ? 60 ? years

Why do the Dutch prefer steel ? they mass produce , is it because they only occasionally see salt water compared with UK boats ? Atlantic are made from fibreglass but their hulls are made in England :confused:
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Think you've answered your own Q's there Daka, except the Ali.....would strongly diagree on the easy self build! Well that is unless you are a highly qualified Ali welder with spotless working conditions, as it's bitch to work with in anything but perfect cleanliness and conditions....IMHO I'll add :)
 
DAKA said:
Just thinking in general about the different types of boat hulls and wondered what the advantages were of each

Fibreglass- last for ? 100 years ?, cheap to mass produce, looks as new for years very light but not practical for one off

Concrete -really cheap for self build but only lasts ? 30 years ? so quick depreciation

Steel-easy self build , last for ? 40 years ? high maintenance

Aluminium - easy self build light but cost a lot lasts ? 60 ? years

Why do the Dutch prefer steel ? they mass produce , is it because they only occasionally see salt water compared with UK boats ? Atlantic are made from fibreglass but their hulls are made in England :confused:
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Really for homebuild there's only one choice: steel.
Grp needs controlled conditions in a heated shed to cure.
Ferro concrete, how do you repair it if it's holed?
Alloy need professional welding....approx. twice the price for fabricated hull.


Plywood's a possibility. MTB's in the war were made from ply ?
 
At 80-90 pounds per cubic foot Fiberglass is not particularly light. Mahogany is about 35 pounds per cubic foot. Aluminum is around 168 and steel 490, ferro cement is roughly 160 (+/- depending on steel content). Cement will last a long time, there are WWII concrete ships still afloat (close to me in Powell River) with zero maintenance in the past 40-50 years. The reason for the low value of cement boats is the fact that it cannot be structurally surveyed without destruction. That and questionable workmanship in most.

Steel is not particularly high in maintenance if the job is done properly(ss on all wear surfaces) and meticulously, which makes it expensive. Aluminum does not need to be painted and so becomes less expensive. Also you don't need the heavy equipment needed to handle steel. It's a lot harder to do really excellent welds in aluminum than in steel, thus steel is better suited to home builders.
 
Steel easy to build with and rust is not a problem as most people suggest if you treat it properly from new, many rust convertors work well so apply one or a good etch primer then epoxy top coats.

Concrete is easily repaired with modern epoxies, particularly the cement based ones now on the market.

Aluminium is no problem for me, TIG weld it.

Fibreglass is not all its cracked up to be, sharp impact mooring can cause internal delamination and lead to other issues.

Basically it comes down to your skill levels.
 
Personnaly wouldnt recomend tig welding a hull. Too slow, too much heat in
and its associated distortion problems. Same goes with steel.
Mig welder, high current and fast work and weld speed.
 
If you can keep up with a mig i would be very surprised.
If you are just planning on keeping distortion down, then I'm glad I'm not paying for the privilege of it been tig welded for the sake of it.
Correct tool for the job and all that.... As much as i love tig welding, not in this scenario...
 
"Just thinking in general about the different types of boat hulls and wondered what the advantages were of each"



"Concrete -really cheap for self build but only lasts ? 30 years ?"

The Medway is littered with concrete lighters and coasters built in 1940s all in remarkably good condition even after lying neglected for the last 75 years.Most of them having had very hard life indeed.The concrete looking as good as when it was built. Many have had holes punched in the side to make the b""""""s sink.
 
Thanks for all the replies :)
I helped make a cement boat a couple of years ago, very interesting and I'm pleased to hear the life expectancy is much longer than I thought.

I started the thread as I was interested why the Dutch dont know how to build in GRP and wondered if UK / USA specialised in GRP due to most boats being submerged in salt water.

I expected the steel in cement boats to rust rapidly but obviously not.
 
The steel is chemically protected by the cement.
Check out some of the older platforms in the north sea, concrete, and over 30 years old. The Brents are one...(except Brent A, which is a steel jacket, if memory's working)
 
Robg71 said:
The steel is chemically protected by the cement.
Check out some of the older platforms in the north sea, concrete, and over 30 years old. The Brents are one...(except Brent A, which is a steel jacket, if memory's working)
Click to expand...

Some old steel reinforced buildings suffer from rust in the steel which causes the concrete to crack and fall off exposing the steel rods.
Do i presume the stronger ?(2:1)? boat / oil rig cement mix acts differently top protect the steel in building concrete .
 
There must be reasons why:-

Charter/Cruiser/Racers go for GRP or even carbon reinforced plastic.

Steel is a very Dutch thing - maybe they have lots of barge makers.

Aluminium is very specialised and hates other metals.

Ferro is largely out of fashion.

Wood is barely used any more, except for -

Ply (stitch and glue), is home made.

Maybe they speak for themselves?
 
RAI said:
There must be reasons why:-

Charter/Cruiser/Racers go for GRP or even carbon reinforced plastic.

Steel is a very Dutch thing - maybe they have lots of barge makers.

Aluminium is very specialised and hates other metals.

Ferro is largely out of fashion.

Wood is barely used any more, except for -

Ply (stitch and glue), is home made.

Maybe they speak for themselves?
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Speaking from my own experience of steel, there's a lot more work than you would imagine constructing a hull.
I used a stick welder, but even with a mig there's still hundreds of feet of weld in a boat.
Fabricating a large hull is a job for a crew of welders, purely from the sheer amount man-hours needed.

In retrospect, If I wanted to build another boat, I'd definitely buy a GRP hull moulding and fit it out myself.
On a smaller scale i got a quote for a Mitchell 22' hull and superstructure for £12k, including prop tube.

Wild guess: 40-50' hull moulding about £1k per foot, amazing value when you think of all the thousands of hours it would take a home builder to complete just the hull and superstructure.

i imagine there's lot's of the traditional british designs would be available for home finishing, especially with the recession.
 
Concrete and the Passive Layer

Although steel’s natural tendency is to undergo corrosion reactions, the alkaline environment of concrete (pH of 12 to 13) provides steel with corrosion protection. At the high pH, a thin oxide layer forms on the steel and prevents metal atoms from dissolving. This passive film does not actually stop corrosion; it reduces the corrosion rate to an insignificant level. For steel in concrete, the passive corrosion rate is typically 0.1 µm per year. Without the passive film, the steel would corrode at rates at least 1,000 times higher (ACI222 2001).


Borrowed from a website... Its explanation is far better put than mine....
 
Robg71 said:
Concrete and the Passive Layer

Although steel’s natural tendency is to undergo corrosion reactions, the alkaline environment of concrete (pH of 12 to 13) provides steel with corrosion protection. At the high pH, a thin oxide layer forms on the steel and prevents metal atoms from dissolving. This passive film does not actually stop corrosion; it reduces the corrosion rate to an insignificant level. For steel in concrete, the passive corrosion rate is typically 0.1 µm per year. Without the passive film, the steel would corrode at rates at least 1,000 times higher (ACI222 2001).


Borrowed from a website... Its explanation is far better put than mine....
Click to expand...

i've seen concrete building beside the seaside that have suffered from concrete cancer, where the re-bar has rusted and expanded, cracking the concrete.

maybe a dodgy cement mix?
 
Plus bad workmanship etc etc.
The rebar has to be in... To be protected, and will corrode if there are avenues for moisture etc to track down.
Then you get the spalling and cracking as the corrosion expands.
 
Robg71 said:
Plus bad workmanship etc etc.
The rebar has to be in... To be protected, and will corrode if there are avenues for moisture etc to track down.
Then you get the spalling and cracking as the corrosion expands.
Click to expand...

i think that's what's happened on the westend flyover into London, all the steel reinforcement has rusted through, because of the salt from the winter ice gritting has percolated down through the concrete.
 
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