Advantages of Fibreglass / concrete / steel / aluminium

[hartcjhart]

as an aside, what are the insurance differences

 

[michael_w]

Don't forget that ancient boat building material - wood!

A lot of the American game fishing boats are cold moulded. Cedar strip with composites is a very strong and relatively cheap way of building one-off hulls.

 

[rustybarge]

Lotus cars chassis' are constructed by bonding alumium, rather than riveting. it's used in aircraft construcion with ally honeycomb panels.

i'm building a hardtop for my Cat, and i've ordered these alumium sandwich panels, €38 for a 8' by 4' 3mm:

http://www.aalco.co.uk/_downloads/literature/aalco-panel.pdf

looks like they might make a fantastic material to construct a superstructure on a boat, light and rigid.
look at the stiffness chart for this material.....impressive or what!
i'm hoping to be able to walk on the roof.

Next question;
what do I use to bond the sheets together: Epoxy glue, or grip-tite type material?
should I pop- rivet the sheets to the frame, or will they leak after a while?
Do i need to seal the rivet mandrel holes?
do I need to use the outrageously expensive monel rivets, or will alloy ones do with duralec compound?

View attachment 36285

 

[alant]

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

I notice that your in Buryport.
Surely, they make all the boats in there, out of camel skin, due to the amount of sand in the harbour.

 

[alant]

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

I seem to remember something called 'hydrogen embrittlement', which caused Liberty ships to break apart, when in cold conditions. This was due to embrittlement either side of a weld.

How would a self build deal with that?

 

[RobWales]

I notice that your in Buryport.
Surely, they make all the boats in there, out of camel skin, due to the amount of sand in the harbour.

Hi Alan,
You're not far off the mark there!
The "Marina"/sand pit has been filling with silt since converted from a tidal harbour to an impounded by tidal flap gate Marina! 8/10 yrs ago...
Very poor design IMHO and everyones else's for that matter, and the company who proposed it's installation should be strung up!!!!
Council in fairness have tried various dredging method's but as that Canute bloke said back in the day, you can't stop it.....
Not sure what the next plan is?...but seeing sandbanks break the surface on maximum impound levels aint a good thing!

 

[alant]

Hi Alan,
You're not far off the mark there!
The "Marina"/sand pit has been filling with silt since converted from a tidal harbour to an impounded by tidal flap gate Marina! 8/10 yrs ago...
Very poor design IMHO and everyones else's for that matter, and the company who proposed it's installation should be strung up!!!!
Council in fairness have tried various dredging method's but as that Canute bloke said back in the day, you can't stop it.....
Not sure what the next plan is?...but seeing sandbanks break the surface on maximum impound levels aint a good thing!

I delivered a boat into Buryport just after the harbour had reopened as a 'new' marina (a steel Dutch ex Pilot Boat), from Neyland, where I had delivered it some years previously, from Le Havre (owner wanted location closer to Swansea). Then had to go back a couple of years later, to take it back across to the Seine, before it became stranded permanently.
I heard, that it was due to local 'jobs for the boyo's' situation & some greasy hands.

PS Didn't think much of the sparse nav buoys & marks in the Loughor Estuary either.

 

[Assassin]

Poor welding caused this, also using incompatible welding rods or wire can cause it, the weakest point of a weld is immediately either side of it, also incorrect welding power causes a lack of penetration which could also cause it.

Remember that any weld is laid in an expanded state (hot) and as it cools it contracts and creates stress just in the weld, normally with a correct weld it isn't a problem, but cool it too much and it becomes brettle just as steel can in extremes of cold.