Hull Thickness

[arf77]

Hi,

I'm hoping to buy a dutch steel cruiser from Holland. I've been told that 5mm is advised for hull thickness however, this boat only is only 4mm thick - does anyone have any advice on this? Is this too thin? Will it affect sale value etc?

Any information would be very gratefully received.

Anna

 

[chrisc]

4mm seems common,I looked at one at the weekend which varied from 4.2 mm to 2.7mm .in this case I would definitely have had more steel added on the thin area.Has 'your' boat got measures all over the hull area ?when were these measurements made?

 

[Norman_E]

It depends to some extent on the size of the boat. For weight reasons small steel boats are often built with 4mm plate, with thicker steel at some key points. It is important that the hull is reinforced with ribs and stringers to give rigidity. A surveyor who specialises in steel boats should be able to advise whether the construction is adequate, and look for any wasteing, leading to thin areas.
Heavier plate is normally is used on large steel yachts.

 

[KellysEye]

4mm is normal, our Dutch built boat is just that.

 

[boatmike]

This is all too generalised. The structural strength of any hull is a function of overall design. You don't say how big it is, what sort of boat it is, how old it is or it's intended usage. We need to know all these things and also if possible who built it, who designed it, what sort of construction (hard chine or round bilge form) etc. The fact that it is built out of 4mm plate is not a problem in itself, I have seen 60metre warships built with only 6-8 mm plate...... I have also seen some pretty horrible yachts built with very heavy plate. If possible ask for the designers scantling drawings. If you get a blank stare start to worry. If they are confidently produced and it is a known designer and builder you can feel more confident. Either way you should be commissioning a survey by a reputable surveyor. You will need one to ensure it anyway.

 

[Whitelighter]

[ QUOTE ]
You will need one to ensure it anyway.

[/ QUOTE ]

or even Insure it.

 

[arf77]

Thanks very much for the replies, I'm going to get the boat surveyed anyway but just wanted to check first that 4mm wasn't unreasonable. The boat isn't a yaught (sorry, this seems to be the best forum and I wasn't sure who else to ask!) but is a steel dutch cruiser, Length 16 m. breadth 3.50 m., it was built in about 1912 and has a riveted hull. I'm hoping to live on it on the Thames (i.e. tidal).

Thanks again for your help,

Anna

 

[richardandtracy]

The limiting factor on plate thickness is the size of the rectangle between frames and stringers. Take the minimum of the two dimensions on the rectangle. From custom & practice this distance shouldn't be much more than 600mm for a 4mm plate. If 450mm or less, then you've got a battleship.

BTW many of the older Bruce Roberts 'Spray' type vessels are from 3mm plate and are built like tanks.

The use of hot rivets is the thing that would make me a little more wary than the plate thickness. Have a good look for inter-hole cracking. Rivet holes are a good place for cracks to develop. However, no more than one plate at a time should fail..

Regards

Richard.

 

[Alastairdent]

Must be over 4mm to get insurance in the UK.