Opinions about Cored Hulls ...

[DerekKelsall]

The rotting foam core you have seen cannot have been the RIGHT STUFF. In 1969 I built a concrete slipway in Sandwich in Kent and used foam off cuts between the runs of concrete. Six years ago (i have the photo) the foam was still standing proud of the concrete showing square cut edges. My daughter has a garden chair which started life in 1965 as a trail around the frames for the outriggers for Toria (Round Britain winner 66). The bulkhead is the seat. all edges are cut, exposed foam and fiberglass. After 47 years exposure the foam is still good as is the painted outside. the unpainted fiberglass has the resin leached out.

Buying a cored boat, always ensure it is PVC foam of 70-80 kg/cu.m. or Corecell. All quality boats are now cored this way. A few US/ Canadian major builders did not make good decisions when choosing and using core sandwich.

A number of US surveyors condemn all core below wl. This view is not supported by what happens in practice. Classification Societies do not request solid below wl.

Happy boating,

Derek.

[s/v Jedi]

Originally Posted by DerekKelsall

The rotting foam core you have seen cannot have been the RIGHT STUFF.

Indeed, not the right stuff, just like the rotten hulls with balsa are not the right stuff. Hulls from quality builders like TPI (USA), Contest (EU) etc. do not have these problems.

p.s. there are a lot of rudders that are wrinkled with "melted" foam core inside. On this forum there were several cases discussed in the past.

[joemac4sail]

Originally Posted by Don Lucas

Just how does one tell by "looking around" whether a hull is cored?

Well Don
that's what I do, I look at boats. , I have sailed,rowed,dived and worked on them for the last 35 years and I am still learning. By the way,there is only one HR in the water at my local marina. Most of the sail boats here are nearly all from the major European builders, Benateau, Bavaria and janneau That is why any visit to a marina is not complete without a walk around looking.
Regards Joe
PS some comments on another forum YBW, about a 2008HR with core problems.

[Carlisle Spirit]

Originally Posted by noelex 77

If you want number of hulls produced look at manufacturers like Beneteau.
If you want top quality, which only happens with smaller numbers look for manufacturers like Amel ( if you don't want an Oyster or a Rustler )

You could add Tayana onto that list - although they are not physically locted in Europe, all their boats have been designed by European designers and are super solid , but still sail very nicely

Carlisle Spirit

[minaret]

Originally Posted by s/v Jedi

Defrek, are you saying that foam cores do not rot? I have seen rotting foam cores...

And how about the melting foam core in rudders?

Seen lots of wet or even delaminated foam core, but never rotten. Pretty sure only UV degradation could do that to closed cell PVC foam. Quality foam core definitely does not rot. The foam in problem rudders is pour foam, totally different animal.

[noelex 77]

Rot problems are confined to balsa cores, but delamination seems much more common in foam cores.

[Tortuga's Lie]

Not having any direct experience with foam cores makes me bow out of this part of the discussion but as far as FRP resin, I would think it would have a hard time adhering to the PVC with out some sort of "teeth" to grip and even then, how tough is this bond? I guess maybe there's a binder??? I know epoxy and resin "pop" right off of my plastic palates.

[sailorboy1]

Originally Posted by joemac4sail

Well Don
that's what I do, I look at boats. , .

Well that sure didn't answer the question of how you can tell a boat is cored by walking the docks, which is why you don't seen to think the boats in your marina have cored hulls!

[joemac4sail]

Sorry Don I stand corrected. There are a few more cored hull boats here in Dun Laoire notably about 6 or so newish 109 that seem to have be the begining of a replacement fleet for the older Sigma fleet, they were bought before the recession hit. But as regards Cruising boats with the exception some notable boats like the HR, an Etap and a 30 ft Freedom Ketch there are not an awful lot of cored hull boats. The 3 big builders on this side of the pond have come to dominate the market for new affordable boats. So, when anything unusual like an custom FRP, a steel or aluminium boat shows up, I'm interested. We're unfortunate here, in that many of the small boat builders lost out to competition. recessions, and European Regulation. The cost of importing a boat from the US in tax and then getting it CE compliant, has prevented alot of US and other internationaly built boats, from being imported for sale in Europe.
Regards Joe

[Dockhead]

Originally Posted by joemac4sail

But as regards Cruising boats with the exception some notable boats like the HR, an Etap and a 30 ft Freedom Ketch there are not an awful lot of cored hull boats.

Ah, you may not recognize them, but once you have eliminated cheaper mass produced boats like Bav, Jen, and Ben, everything will be fully cored, almost everything. A few exceptions like Oyster, Amel, and Nauticat, are not fully cored. But I'm sure in Ireland you have your Swans and so forth. They're all cored.

[motu42]

We have a Kelsall cat, 15 yrs old now, built entirely in PVC foam core and polyester glass outers. Its light, strong, and durable. A recent full strip and paint proved no core problems at all.

Kelsall pioneered this method of construction, and he is adamant the key is the right sort of cores and QA in construction. His boats last very well, 40 years plus for race hulls is pretty good.

There are a lot of core materials, and they behave differently. So all "foam core" gets a bad wrap when some-one uses polyurethane or other unsuitable core (PU sadly disintegatrates to dust with vibration). Likewise some-one will use end-grain balsa, and not take due care to seal out water - it will rot, like all wood.

There are certainly plenty of rusty steel hulls out there - should we write off steel as a hull material? Or is it a matter of suitable paint/anode protection?

All materials have limitations - wooden boats rot, glass gets osmosis, steel rusts, etc. The real question is whether its properly built, using suitable materials, and properly maintained.

Personally I have had glass, glass/ply and PVC foam boats. On balance I will always go for PVC/foam next time.

[Cheechako]

In about 1999 I was looking at new boats. Focused on the Hallberg Rassy and Wauquiez. At that time Wauquiez was touting a new hull concept that was a cored hull with about a 1" thick rigid foam core. the foam (actually it was too dense to be called foam really) was more like a lightweight epoxy, very hard and dense and foamy looking but hard as a rock. Anyone know anything about this? The sales office had a a hull portion there that showed the concept. It looked like the best cored concept I'd ever seen.... I dont know how they did it, but must have made 2 hulls, an inner and outer, and then injected it between....

[ntolst]

When I was looking for a boat I considered one Niagara 35' in MD which had a cored hull. The boat looked very nice but survey revealed major hull delamination caused by water penetration.
NT.

[motu42]

From boatus.com:
"Both the hull and deck of the Niagara 35 are constructed of a composite of fiberglass cloth, resin and balsa wood core."

Obviously water got in, and as we know balsa and water are not good friends...

PVC foam core boats like our Kelsall dont even have core edges sealed! The PVC foam is closed cell so it doesnt soak up water, (although water can travel very slowly through it via internal voids). It doesnt go soggy/rotten/delaminated when wet.

Derek Kelsall's nailed it when he says 'the RIGHT materials'
Rob

[s/v Jedi]

Originally Posted by motu42

From boatus.com:
"Both the hull and deck of the Niagara 35 are constructed of a composite of fiberglass cloth, resin and balsa wood core."

Obviously water got in, and as we know balsa and water are not good friends...

PVC foam core boats like our Kelsall dont even have core edges sealed! The PVC foam is closed cell so it doesnt soak up water, (although water can travel very slowly through it via internal voids). It doesnt go soggy/rotten/delaminated when wet.

Derek Kelsall's nailed it when he says 'the RIGHT materials'
Rob

Sorry, but that does not sound like anything to brag about imo... whenever water ingress can occur, problems follow. Put a little piece of PVC closed cell foam in a jar of seawater for a week. Next drain the seawater out the jar and close the lid with the foam inside for another week... you will find that things are rotting in there and many chemical substances have entered with the water or are the result of the organic decomposition, some of which will deteriorate the PVC foam.