Foam Core Hull

[a64pilot]

Originally Posted by Cheechako

In these discussions there is no "best" really. I think what is often missed is tempering your choice with hierarchy of risk..... and what your personal comfort with risk is. Both trouble, $, and personal risk should be considered.
-When you choose a hull, if you choose an old boat with a bolt on keel, you have higher risk than a boat with a molded keel. Your risk is primarily $, that the keel will subsequently need to be removed and rebedded /rebolted....but brand new boats with bolt on keels have lost them also.
-Cored hulls have the risk that they will have delamination and or wet core issues. It's a real risk, many have had the problem. But sure, you may not.
-Spade rudders are more at risk than supported rudders. They bend, break off, break off leaving a big hole when they take part of the hull with them. A well built one may have lower odds of this problem and you may never experience the problem, but there is risk As a sailor I often used the risk factor to make decisions and lessen risks whenever I can; weather predictors lessen risk so I use them. Short cuts thru coral infested shallows, even with good charts and gps, are riskier, so I avoid them. Spade rudders, cored hulls, propane in normal lockers are risks, I avoid them. Etc etc.


Your decisions about risk are different than mine. Act accordingly.

You know this is it actually in a nutshell.

Completely different thing, but the same really, a turbocharged, common rail Diesel is "better" than an old fashioned mechanical injection Diesel, it makes more power with less weight and burns less fuel. By almost everything measurable it is "better". It is more expensive though.
I don't want one, I want an old fashioned chug, chug mechanical injected Diesel that I can fix with a minimum of spares and I will accept that it burns slightly more fuel, weighs more which robs boat performance, and takes up more room.
Same with the hull, God forbid I should damage her, but as long as she doesn't sink even with my limited experience, I can affect a repair if I can get her out of the water long enough.
I gave up performance for a full encapsulated keel, a well protected prop and rudder and a deck that cannot absorb water and a solid glass hull.

Depends on what is important to you, that is why there are so many boat designs, cause people prioritize different things

[barnakiel]

A solid hull is not better, nor is a cored one.

Well done hulls give no trouble. And if the boat is cored below waterline, you do not want to make a big hole in it.

But neither you want to make a big hole in the underwater portion of a solid hull ... OR DO YOU?

Cored hulls are 100% fine. If you have your reservations, simply buy a solid hull.

b.

[noelex 77]

Cored hulls in many regards are nicer than solid hulls. The are much stiffer, quieter, and have better insulation.

Problems with cored hulls are not common, but where they occur they can be devastating. The incidence of issues, particularly delamination, seems much higher in long distance cruising boats. Cats seem especially vulnerable.

These problems are not often discussed on forums. I suspect most owners recognise that they need professional help. Owners, and factories are keen to minimise publicity. Some brands have been mentioned in this thread as "never suffering core problems" hmmm.

If you are purchasing a long distance cruising boat a solid hull without a structural liner is the better choice in my view.

[smj]

Originally Posted by leftbrainstuff

I have designed, built, tested and certified composite structures for defence, aerospace, automotive and motorsport systems since the mid 80s.

But you are correct I have never held the title composites engineer and yes I have a solid hull with a cored deck and a cored hard dodger. The hull and deck are original. The dodger is my own fibreglass, kevlar and carbon design.

Why would you build a dodger out of carbon and Kevlar?

[Colin A]

Originally Posted by captainstubbie

Part of my concern is damage from a minor collision with something harder or sharper...are they as tough to ding and easy to repair?

Depends on how it's built for collision and damage resistance. Repairing is slightly more complicated then a regular single skin repair, but almost any good glass shop can handle it with ease.

[Colin A]

Originally Posted by smj

Cheaper to produce? You sure about that?

Yeah to do it well It's not really cheaper.

[robert sailor]

Originally Posted by noelex 77

Cored hulls in many regards are nicer than solid hulls. The are much stiffer, quieter, and have better insulation.

Problems with cored hulls are not common, but where they occur they can be devastating. The incidence of issues, particularly delamination, seems much higher in long distance cruising boats. Cats seem especially vulnerable.

These problems are not often discussed on forums. I suspect most owners recognise that they need professional help. Owners, and factories are keen to minimise publicity. Some brands have been mentioned in this thread as "never suffering core problems" hmmm.

If you are purchasing a long distance cruising boat a solid hull without a structural liner is the better choice in my view.

Solid hulls and stick built construction is my favorite as well. Long distance and years of cycling isn't overly friendly to some boats built with full liners but for 98% of the normal usage a sailboat gets they seem to be adequate.

[Colin A]

Originally Posted by double u

lets not degenerate this thread to a pissing contest please!
1. @interior liners/gridpans: there a many different kinds, some grids (a grid of carlings/stringers & floors) tabbed to the hull - the tabbing can, if difficult, in general be inspected, & the much more difficult to inspect completely closed type that is glued (bogged?) to the hull (gluelines inaccessible)
2.@cored structures: lets not lump a quick-&-dirty balsa/csm-sandwich together with a hightech sandwich made up from unidirectional carbonfibres & very expensive cores.
3.it would be conducive if the owners of cored boats here on the forum would NOT view any negative comments about cored boats as personal insults

I think #2 is the issue here, you can build a crappy boat either way. But it's easier in general to mess up a cored boat. I have little problem owning a cored hull from a good builder (both mine are non cored) but one from an average or low end builder not so much. Cored hulls have become common and despite the knowledge there are still screw ups. In general it's likely safer to buy a solid hull, for an older boat, but I wouldn't avoid all cored hulls out of hand.

[captainstubbie]

I called 3 surveyors and asked them about their experience examining cored hulls below the watetline... 1 had never done a survey on one. 2 said that he really liked them for strength and had no issues with that type of construction. 3 did not like them due to water intrusion & delay. Jury is still out... I am researching more on diy repairs...should the need arise.. Sure like the looks of the Southern Cross...

Sent from my SM-G935V using Cruisers Sailing Forum mobile app

[a64pilot]

Maybe it would be more fruitful to find out if the Southern Cross had any history of core failures?
I saw that as saying that maybe because Bayliners have a problem with something may not mean anything except that Bayliner did it poorly

[daysgoneby]

Cores and Structural Issues

Boat Hulls - Cores and Structural Issues: Online Articles by David Pascoe, Marine Surveyor

[double u]

"Virtually every high performance racing sail or powerboat is cored"
totally invalid argument! longevity, "surveyability" & ease of repair are of no interest in a true racer.
imho we ought to distinguish between new & used cored (or gridpan)-boats:
new: perfectly acceptable, as 1. owner I know what I put the boat through in the ways of groundings, collisions etc. & subsequent repairs & their quality
used: no such knowledge...and then the much more difficult "surveyability", serious structural defects resulting from minor damage or incompetent/slapdash repairs & subsequent repaircosts getting out of hand becomes an important factor for me as a possible buyer.

[daysgoneby]

The Ins and Outs of Cored Composite Construction | Steve D'Antonio Marine Consulting

https://www.proboat.com/2010/05/morris-core-repair/

Swan 45, Extensive Repairs & Updates

FIBERGLASS BOATBUILDING: Cored Laminates

http://www.bpspecialprojects.com/PDF...20PROBLEMS.PDF

Storm Damaged Boats Reveal the Limits of Fiberglass Hull Construction - Practical Sailor Print Edition Article

Do fibreglass and carbon fibre mix? | M.B. Marsh Marine Design

http://www.marinesurveyor.com/articles/hotvac.html

[Polux]

Originally Posted by double u

"Virtually every high performance racing sail or powerboat is cored"
totally invalid argument! longevity, "surveyability" & ease of repair are of no interest in a true racer.
imho we ought to distinguish between new & used cored (or gridpan)-boats:
new: perfectly acceptable, as 1. owner I know what I put the boat through in the ways of groundings, collisions etc. & subsequent repairs & their quality
used: no such knowledge...and then the much more difficult "surveyability", serious structural defects resulting from minor damage or incompetent/slapdash repairs & subsequent repaircosts getting out of hand becomes an important factor for me as a possible buyer.

I really don't understand the point of this discussion. On an old boat, for the ones that buy that type of boats special care is needed in what regards buying a cored boats and the boat has to be thoroughly inspected. If there is not water on the core and had been so on the last 20 years, than the chances are that it will not have problems on the next 10 or even more.

But we are talking about the best way to built yachts and that means new boats and regarding those all new expensive boats, the ones from whom the extra cost is not a problem, have cored hulls. Most of them fully cored some only cored above waterline.

The ones cored only above waterline are from the more traditional brands that make boats for the more conservative sailors, meaning the ones that are more slow in what regards accepting boat design evolution and better and new solutions and the reason why they are not fully cored has to do mainly with that, selling boats to that type of clients, the same reason that leads some of them to feature also "protected" rudders.

I don't know of any top production yacht (meaning not old designs that continue to be made in insignificant numbers for few and very conservative clients) from the last years that have a fully non cored hull. This should settle the question regarding what is the best way to built a GRP yacht when money is not a problem....but I have the notion that some will still find a way to argument that an all single skin hull is a better option

[Polux]

Originally Posted by daysgoneby

The Ins and Outs of Cored Composite Construction | Steve D'Antonio Marine Consulting

https://www.proboat.com/2010/05/morris-core-repair/

Swan 45, Extensive Repairs & Updates

FIBERGLASS BOATBUILDING: Cored Laminates

http://www.bpspecialprojects.com/PDF...20PROBLEMS.PDF

Storm Damaged Boats Reveal the Limits of Fiberglass Hull Construction - Practical Sailor Print Edition Article

Do fibreglass and carbon fibre mix? | M.B. Marsh Marine Design

Mustin Marine Surveys, Miami, Florida, USA - Hot Vac-A Real Cure for Osmosis?

The only interesting link is this one from a very young designer that says:

"If you're going to start mixing materials, though, you have to understand the load paths involved. Each material has to be used where its properties will do the most good, and the way loads will be shared between materials must be carefully analyzed; mixing them willy-nilly is likely to lead to unexpected failures like the one described above."
http://marine.marsh-design.com/conte...n-fibre-mix]Do fibreglass and carbon fibre mix? | M.B. Marsh Marine Design

That goes in the sense of what I had said before regarding boat building today not to be an activity for amateurs at least if top building is to be provided at rational costs.

It is for what is said above that today a shipyard that built top boats using all the resources materials and technologies that are available has on his team a dedicated engineer for calculating the distribution of forces and structural needs working closely with an engineer in composites that will tailor for each part of the boat the most indicated solution, using different types of fibers with different properties.

Even if interesting that quote regards the type of boats he designs and built with projects sold for amateur boat building, these ones:




http://marine.marsh-design.com/content/boat-designs