Boat Builders and the Credit Crunch

[jfm]

[ QUOTE ]
as for JFM point 1 was that more thickness gives more stiffness as you highly say, that is what I gave the 1 inch example, if you put 1 inche ogg boxes you migh have mote stiffness but not the desired strength a more time consuming all GRP moulding would do

[/ QUOTE ]

No, the strength given by a 1 inch solid GRP isn't desired. It is MUCH more than is desired.

Look, you need a certain strength and a certain stiffness in a hull panel. Strength and stiffness are different things. If you use solid GRP, you will get the desired strength MUCH SOONER than you get the desired stiffness. So, how do you get the stiffness? You can keep adding GRP till you get the stiffness, but that adds cost and weight, and strenght that yopu don't need. Or you can add an Airex core which is zero weight, zero extra strength, but an ORDER OF MAGNITUDE extra stiffness. It's easy. Coring is better, away from hull bottoms

Remember, as I said above, much of engineering design is about stiffness. Take a steel beam used to construct a syscraper or the floor in an office building. It could be say 100mm square and be strong enough. But it would bend like a piece of rubber. Take the exact same materal, and make it a "I" or "H" section (where the middle web acts like the Airex core in a boat hull) and you get the same strenght but an order of magnitude increase in stiffness.

Stiffness in panels is mostly about shape. Taking the same 20mm grp layup and changing its shape to two 10mm layups separated by a 20mm Airex core and you increase the stiffness, using exactly the same amount of material.

Oooh, gotta go, got a stiffy /forums/images/graemlins/grin.gif

 

[Whitelighter]

[ QUOTE ]
Cored boat hulls have a number of issues as outlined in David Pascoe's articles here

Persoanlly, I'm intending to stick to hulls that have a solid bottom!

[/ QUOTE ]

Be fair ade, those are all on boats 15 years old with Balsa cores - very nasty but also not what is being discussed. I would like Pascoe to look at a modern foam or Dyvinicell boat is the same detail.

Dont buy another boat, or not one thats less than 15 years old becuase it will have a foam core in the sides and deck.

 

[PowerYachtBlog]

to be exact he does not criticise coring wheter balsa or foam in the sides, he says that if you drill a hole in it or someone has as in second hand boats, you will have some problems unless the work is professionally done

he also says a good word about Airex, and also on coring he is realistic and say it can be good but it depends on the standard of the yard
I think a surveyor perspecitive is different from an engineer one, I prefare the former as he speaking about facts and what happened to boats after 5 and 10 years of usage, they all shine new but they are not all that good after 10 years

 

[AdeOlly]

I've no problem with the sides or coachroof - indeed my 305 has a balsa cored coachroof - but I'm not convinced about the longevity of a cored bottom, and given the amount of £££££ invested in a boat and the difficulty of fixing a damaged hull core, I'll take the hull with the solid bottom thanks.

 

[capsco]

Seems like a bit of thread drift here chaps.

 

[MapisM]

[ QUOTE ]
surveyors ... are ... not smart enough to be engineers

[/ QUOTE ]ROTFL, nice one!!!
We could push that concept even farther by saying that (on average) they are actually much smarter than the engineers, if you get my drift....

 

[Deleted User YDKXO]

Again guilty of not using words accurately. I meant hull bottom and, yes, if designed and produced properly, a laminated cored panel will be stiffer than an all grp one but, much of that stiffness comes from the bonding process. If that bonding process is inadequately carried out then that can lead to weakness and failure of the structure. I don't doubt that Fairline's quality supervision is first class but is it so at every other builder using this process? Also as poweryacht has already pointed out, if you make a hole in a cored panel, you then risk water ingress which also puts the structure at risk
I don't buy the idea that using divynlcell or whatever cores is an entirely engineering led idea. There has to be an element of cost saving for the builder otherwise they wouldn't use the technique so much

 

[Deleted User YDKXO]

I had a little chuckle about that too. I deal with a number of European manufacturers of construction equipment and often have meetings with their engineers and invariably, they're all highly educated, highly qualified and very diligent but common sense and experience is often in short supply
Basically if computer say yes, its OK and if computer say no, it's not

 

[jfm]

Yes, indeed, if the bonding is no good then you do not get the stiffness benefit. A core sandwich filling only works if it resists shear movement between the two slices of bread.

That said, it isn't hard to do. If a builder gets it wrong they're not very good.

The water ingress was a big deal with balsa, but isn't a big issue now with Airex and all these nice sikaflex etc sealers that have been developed in the last 10 years. Installing a fitting thru a cored laminate and letting water get in the Airex requires an incredibly bad fitter these days. And if it happens hardly any harm comes to the Airex. Pascoe goes on about hydraulic erosion but he is talking cobblers on that point - the water doesn't spread far enough to make that happen (it did with balsa, but that's different)

On the cost saving/engineering I think this is a happy case of no conflicts. Builder wants to achieve a certain stiffness without adding weight and cost. Airex just does that incredibly well, and adds very little cost. alterntively builder wants to strip out some cost - he can do that by using Airex to get stiffness in lieu of other more expensive methods. It's not a case of "we'll use Airex becuase it saves money even though it reduces quality", happily

 

[PowerYachtBlog]

lol I have twisted this post

but it got interesting hehe

 

[jfm]

Yeah, it got twisty, hehe, I'm guilty too We're all quite good at arguing even when we're basically saying the same thing ))

 

[EME]

Engineers Fall Out !

For YEARS I've been waiting for one of you to write that

[ QUOTE ]
engineers.... invariably, they're all highly educated, highly qualified and very diligent but common sense and experience is often in short supply

[/ QUOTE ] /forums/images/graemlins/wink.gif

.. only issue being that I've been falling the 'argument' diligently. I'm a lost cause! /forums/images/graemlins/shocked.gif

 

[RogerRat]

[ QUOTE ]
Hi i am very surprised indeed with the poll so far)&yes i do have a failine myself

[/ QUOTE ]

I also have a Fairline but I think they've got it wrong at the moment and that is why I think they're going to suffer. /forums/images/graemlins/frown.gif

Two of their best models, the T40 and the T48 have been terminated. The T52 is huge in comparison, the T44 is much bigger than the T40 but with no garage and the new all singing Squady 55 has a staircase missing upto the flybridge from within... all in pursuit of the main athwart ships owner's cabin.

They may have it right in the med but in the UK, I'm not so sure. /forums/images/graemlins/confused.gif

Squeakers' sell in a differnet maket mostly and the Princess lacks the level of finish comparison. (but excellent value)

I'm also of the opinion that Sealine are the weak link here. Their best boats were the S24 type upto the F43. In this sector, they took a lot of beating. There are loads of very satisfied Sealine owners on here with S28 to F37s' that are totally satisfied with the space, performance, finish and value.

I'm yet to be convinced about the new Sealine SC slab sided models. /forums/images/graemlins/confused.gif

 

[PowerYachtBlog]

I dont know cause I am far away

but some1 in here pointed out that the Solent is full of the new Sealine SC models or is it not?
Out here in the med, I think of the new ones I see mostly the new Sline T-50
it is still little compared to the Azimuts, Ferretti, Aicons, Carnevali, FL Squadrons or Sunseeker Manhattans but you see a few of them running

the SC outside is nice, may be too nice for a Sealine, and if IMO they fix a few practical issues would be among the top boat in the class but the brand identity is missing which is important for owners coming from the brand

as for the Failine to be honest I prefare the bathing platform then the garage on the Targa 40, LOL I think you can hardly put a push chair in there as if a tender
Targa 44 GT is a great looker, but it costs a hell about a more 100.000 EUROS to a V45,
according to Volvo press release IPS should have reduced the price from the builder due to the less time in fitting out or where they wrong....