Van der Valk 23M in build

[Imperial One]

Sorry Yoeri - I had you down as a Monday to Friday kind of guy!!!
How wrong was I?

 

[deuc02]

Yoeri. Do you recomend your clients put down sacrificial anodes in a marina. Reason i ask is deucy is a 26 year old aluminium yacht and galvanic corosion is a big worry. And have seen the damage a stray 2p coin can do

 

[MapisM]

Pushing the ship through the water (because that is wat happens with a displacement ship) makes the forces on the hull more intense.
At least in certain parts (most likely the bow part of the hull)

Sorry Yoeri, but I really must raise the notorious flag...

I could have accepted your point if you would have said that the forces on a hull which is designed to be pushed through the water are more CONSTANT than on a hull designed to plane on the water. But more INTENSE? No way, imho.

That aside, another curiosity on the matter of welding: have you ever considered cold welding?

 

[wakeup]

Also Yoeri, what measures do you take to check all of the 100s of welds once the casco is complete.?

I must admit, whilst helming a boat made this way, I would worry every time I hit a wave or every bump and thump that a weld was giving way. I am sure I would be obsessively checking the welds all the time. So what % of redundancy do you have in the number of welds?

This is something that doesn't worry me with a monocoque GRP hull.

 

[rafiki_]

Also Yoeri, what measures do you take to check all of the 100s of welds once the casco is complete.?

I must admit, whilst helming a boat made this way, I would worry every time I hit a wave or every bump and thump that a weld was giving way. I am sure I would be obsessively checking the welds all the time. So what % of redundancy do you have in the number of welds?

This is something that doesn't worry me with a monocoque GRP hull.

In many ways it is easier to check the integrity of the welds. There is a magic spray (sorry, can't remember the name, having a senior day) that is used to check welds. There is no equivalent for GRP, which is why some boats suffer delamination issues.

 

[wakeup]

In many ways it is easier to check the integrity of the welds. There is a magic spray (sorry, can't remember the name, having a senior day) that is used to check welds. There is no equivalent for GRP, which is why some boats suffer delamination issues.

I think you are referring to a non-destructive UV crack test. You have to use a flourescent penetrant dye and a UV light source (very specific 395nm light source) to highlight the cracks. Such cracks are usually hairline and not easy to spot versus a GRP crack.

But the problem is you need to be able to get access to the welds and see the welds in the first place. Not so easy once the superstructure is on and boat is fully kitted out for use.

 

[Yoeri]

@MapisM
I think I have expressed myself wrong in that sense.
I meant that in displacement "mode" (our semi-displacement and planing ship can also sail slowly ofcourse) there are more forces in the bow section. In planing "mode" there are more forces (forces of the machines not included) at the middle and rear part of the hull. Sorry for the confusion.


@deuc02
We use sacrifical anodes in all cases. Regardless of the age of the ship. But it depends whether you sail on salt or brackish water.

Salt water
Use zinc anodes (zinc anodes only work on salt water).

Brackish or fresh water
When you sail for 80% (or more) on brackish or fresh water you can better make use of aluminium anodes.


@wakeup
All our welders are certified and are able to recognize imperfections through observing the weld pool. We sometimes build under Lloyds or MCA approval, in these cases the welds are checked on the basis of photo review by the authority. Almost all parts are both on the inside and the outside welded, cracks in the weld are therefore extremely rare.


I will try to post a new set of pics today!

Yoeri

 

[Imperial One]

I could have accepted your point if you would have said that the forces on a hull which is designed to be pushed through the water are more CONSTANT than on a hull designed to plane on the water. But more INTENSE? No way, imho.

Good afternoon MapisM and other followers of the teachings of Guru Yoeri. I know its a Bank Holiday but given the c@*p weather,as ever we are here in the office for a while.
Over the years of working with the Dutch, I have found that just occasionally they do use a word which they think is accurate but to us is perhaps not a word we would use in their chosen context. I think this is a case in point, normally I would have spotted that and come to his rescue earlier and pointed this out but I went to Car Fest instead. Yoeri is a Dutchman who speaks very good English and his written English is also very good, it is certainly miles better than my Dutch but I will endeavour to be watching over his shoulder when I can.
One of my colleagues in Holland once told me that many of them learn English from watching constant reruns of Top Gear - I think it is one of the most popular TV programmes in Holland - I know that Yoeri has been taught English properly so I suggest we should all be thankful that he does not use some of JC's more basic terms of reference!!
Dank u zeer vor het lezen van mijn post en hebben een goode dag - how am I doing Yoeri?

 

[David of Essex]

Sorry Yoeri, but I really must raise the notorious flag...

I could have accepted your point if you would have said that the forces on a hull which is designed to be pushed through the water are more CONSTANT than on a hull designed to plane on the water. But more INTENSE? No way, imho.

That aside, another curiosity on the matter of welding: have you ever considered cold welding?

Love your flag, good sense of humour
David

 

[Yoeri]

Completely true Mike! You are also working on your Dutch? Not bad!

Today I have managed to make a set of new pics. As you can see, the ribs are currently being connected to the underside of the hull.

 

[Imperial One]

Glad to see that Holland is working on a Monday even if the Brits are not!

 

[MapisM]

@MapisM
I think I have expressed myself wrong in that sense.

Fairenuff, all understood now.
Still interested to hear if contact welding has ever been considered for these builds.

 

[Robg71]

I think you are referring to a non-destructive UV crack test. You have to use a flourescent penetrant dye and a UV light source (very specific 395nm light source) to highlight the cracks. Such cracks are usually hairline and not easy to spot versus a GRP crack.

But the problem is you need to be able to get access to the welds and see the welds in the first place. Not so easy once the superstructure is on and boat is fully kitted out for use.

MPI testing.... Magnetic particle inspection.
Its used through out construction and inspection industry.
Requires use of a strong magnetic field, either through permanent or electro magnets to allign the iron filings held in suspension in a florescene solution.
I use it at work inspecting oil and gas platforms for shell, BP, et al.
Works underwater just the same as it does topsides...

 

[Yoeri]

Dear MapisM,

Sorry, forgot to reply on this question!

With cold welding 2 pieces of metal need to be pressed against each other under high pressure. This is very difficult for a complex workpiece (with more than 4000 different parts).

Hence it is not an option for us.


Yoeri

 

[MapisM]

This is very difficult for a complex workpiece (with more than 4000 different parts).

Hence it is not an option for us.

Thanks Yoeri, I was actually guessing that.

In other terms, since more complexity means more costs, at the end of the day the reason why you (and any other steel/alu builder, afaik) stick to "traditional" welding is cost driven - or am I missing something?

I'm curious about that, because since the first time I heard of cold welding, I've always thought that it would suit the boatbuilding needs marvellously.

 

[Yoeri]

Dear MapisM,

That is one of the reasons, but not the most important one.
Moreover, the problem is that there are many difficult to reach locations, so the technique is not always easy to apply.

Yoeri

 

[MapisM]

Moreover, the problem is that there are many difficult to reach locations, so the technique is not always easy to apply.

Mmm... That's still in the higher complexity/cost ballpark, innit?

 

[Yoeri]

Dear MapisM,

Yes it is kind of, you are right!
But even in some situations it even is not possible because the space is simply not there.

Yoeri

 

[wakeup]

Hi Yoeri,

Interesting pictures and speed of progress.

For the benefit of the members here, can you tell us what role you perform at VdV? This will help us frame questions to you in the right way.

Thanks

Wakeup

 

[rafiki_]

Glad to see that Holland is working on a Monday even if the Brits are not!

Speak for yourself!