Rudder Failures

[smackdaddy]

Originally Posted by robert sailor

Glass tabbing and through bolts are seen in many better built boats, sort of a belt and suspenders approach.

Let's see 'em.

[sailorboy1]

Originally Posted by colemj

Keep in mind that they experienced 27-30kt winds with gusts to 40kt. These are not conditions a Hunter or Bene could survive because they are not a Perry-designed "blue water" boat.

Mark

Just a ridiculous statement. Maybe it was suppose to be a joke that failed in typing.

[smackdaddy]

Originally Posted by colemj

Keep in mind that they experienced 27-30kt winds with gusts to 40kt. These are not conditions a Hunter or Bene could survive because they are not a Perry-designed "blue water" boat.

Mark

Heh-heh.

Honestly, what I think that account shows more than anything is that you should not push your boat too hard....regardless of who builds it.

But, I also think it shows a potential mindset that can sink in with people who buy the "bluewater" hype. If you've got an older, "stouter" build - you should be able to easily endure conditions that would break a Hunter or Bene...goes the thinking.

And you can - right up until your "bluewater boat" breaks too.

My lesson from that story is that I need to seriously ease up in steep 15' seas - definitely not relentlessly beat into them if I have some room.

[smackdaddy]

Originally Posted by sailorboy1

Just a ridiculous statement. Maybe it was suppose to be a joke that failed in typing.

It was a joke.

[colemj]

Originally Posted by sailorboy1

Just a ridiculous statement. Maybe it was suppose to be a joke that failed in typing.

Jeez, and you always seemed to me to have a well-developed sense of irony and sarcastic dry humor. Is it getting cold up there?

Mark

[robert sailor]

Originally Posted by smackdaddy

Let's see 'em.

I don't carry water Smack, even for you. Its not that much effort for you to look up, they are there on the better built boats, take my word!

[sailorboy1]

Originally Posted by colemj

. Is it getting cold up there?

Mark

Of course it is cold! So cold already that my boat cracked in half and I will have to plexus it back together in the spring again.

[Dockhead]

Originally Posted by sailorboy1

Just a ridiculous statement. Maybe it was suppose to be a joke that failed in typing.

LOL. Mark circumnavigated in a Beneteau. Joke!!!

[Jim Cate]

Originally Posted by Dockhead

LOL. Mark circumnavigated in a Beneteau. Joke!!!

Uhhh... wrong Mark, Dockie!

Jim

[colemj]

Originally Posted by sailorboy1

Of course it is cold! So cold already that my boat cracked in half and I will have to plexus it back together in the spring again.

Are you serious???

Mark

[Coops]

Originally Posted by Jim Cate

Uhhh... wrong Mark, Dockie!

Jim

Is there a right Mark?

Coops.

[sailorboy1]

Originally Posted by colemj

Are you serious???

Mark

Why wouldn't I be as it sounds to be a common problem and happens regularly ....................... on internet forums

[smackdaddy]

Originally Posted by robert sailor

I don't carry water Smack, even for you. Its not that much effort for you to look up, they are there on the better built boats, take my word!

You're really not very good at this.

I'll just take your word for it.

[Polux]

Originally Posted by Dockhead

Well, the last quote confirms what I just said -- that balsa is preferable where strength is needed. And if you Google "Open 60 balsa" you will see that Open 60's are built the same way -- Nomex honeycomb and foam of various types in big panels -- this is lighter -- and balsa -- heavier but far stronger -- in high stress areas. I have seen them built. Honeycomb is not practical on cruising boats because of the voids, which would instantly fill up with water in case of any hull breach. And even Nomex honeycomb doesn't quite match balsa for strength.

I believe that was long ago. Now IMOCA boats and other carbon racers use a honeycomb, called nomex and sometimes the same thing made of kevlar. As you said I Google "Open60 core" and what I found was references to really old boats, 15 year old ones. If you look at new boats you will not find any reference to the use of balsa. Maybe you can post a single one referring a new boat, meaning 2007 and over using a balsa core?

"In the spring of 2005 construction started in Canada on the fourth Owen Clarke Open 60, the first pre-preg carbon Nomex yacht of its type to be built in North America."
IMOCA Open 60 : Owen Clarke Design - Yacht Design and Naval Architects

Launched 1997, at CNB France for Giovanni Soldini she went on to produce some fine results for this veteran Italian sailor and in so doing helping to establish his name amongst the heroes of the IMOCA 60 Class. Constructed of Nomex cored T700 Pre-preg carbon fibre for hull and deck
IMOCA Open 60 Eco Class - Ex 'Fila','Saga' : Owen Clarke Design - Yacht Design and Naval Architects

Like all the racing prototypes built by Multiplast, Brit Air will be made of a carbon sandwich using a honeycomb (Nomex ) core, and oven cured. The build process will imply female carbon moulds, in order to ensure perfect dilatation homogeneity during the curing phase.
Multiplast to build the new Brit Air Imoca Open 60’

As you know multiplast build most of the French big racing boats, have a look:
MULTIPLAST Boat Yard – Building of racing multihulls, conception, composite material fitting
MULTIPLAST boat yard – building of racing monohull
They all are built this way:Like all the racing prototypes built by Multiplast, ... made of a carbon sandwich using a honeycomb (Nomex ) core,[/COLOR][/B] and oven cured. The build process will imply female carbon moulds, in order to ensure perfect dilatation homogeneity during the curing phase.

As you know there are safety rules regarding the way a Imoca (Open60) can be built and there are authorized materials that are considered to be the ones that would give them the strength to survive the conditions they encounter. Balsa for core is not authorized. This are the 2014 rules and these are the authorized materials for the hull building:

B.10.1: Boats having a first measurement certificate issued after 1, May 2013:
The hull of the boat less associated deck hardware and all the corrector weights shall be built with respect for the following specifications:
- HR fibers are allowed and limited to the following fibers :
o Toray T800H
o Toray M30S
o Toray T700S
o Mitsubishi Rayon MR40
o Hexcel IM 7 (6k)
o Tornel T650/42
o And any fiber having been a prior acceptance of the Chief Measurer
- Nomex core maerial or foam
- Film adhesive 300g/m² minimum
- Non-adjuvanted resin (no nano-techs)
- Weight of the tissues150g/m² minimum

Originally Posted by Dockhead

Most high-end boats still use balsa, at least in high stress areas of the hull, and certainly in decks, where the strength and stiffness are especially important.

It is not true to say that balsa is "old school"; foam is "modern". An engineer would laugh at such an idea. They are different materials with different properties; not football teams. Balsa is supreme for compressive strength, but may be too heavy for very large panels which have been engineered to have enough strength without it. Balsa is also less elastic and absorbs less energy -- so where a design needs energy absorption, then foam is better for that. Balsa is more tedious to work with -- another reason to use foam if the strength of balsa is not needed. Engineers decide what tradeoffs to make in any given design.

Yes, balsa core can be used on small parts of the hull to make it more rigid but when we say that a hull is balsa core that means that all the hull is balsa cored and not some small portions. When we say that a hull is foam cored that means that almost all the hull is foam cored even if it has aluminium or balsa small inserts on areas subject to more stress.

I am curious about those "most high end yachts that use balsa core" can you name a few? I mean not ones that use only top sides (out of the water) cored like Oyster but ones that use a full cored hull?

Halberg Rassy use foam core, Swan use foam core, Solaris use Airex for core, Aeroyacht (wally) use foam core, wally monohulls that are carbon yachts use "The hull core is mainly of Nomex aramid honeycomb, though CoreCell styrene acrylonitrile (SAN) has been used for the high-stress slamming areas.", Brenta use foam core, Arcona use Divinycell, Xyachts use foam core, Advanced yachts use PVC core, Discovery yachts use Corecell M-Foam core, Waukiez use foam (used balsa years ago), Faurby use divinycel core, Grand soleil use PVC foam, Comar use Airex, Najad use Dyvinicell, Luffe use foam and so on

You can still find some builders that use balsa cored hulls, most for topsides where the risk of water abortion is smaller but they are invariably very conservative brands, the ones that took more time to pass from a modified fin keel to a fin keel and from a skeg rudder to a spade rudder. But with time they will change from Balsa to one of the polyesters. The risk of water intrusion is just too big, balsa absorbs water and as all wood it swells and that provokes delamination.

There would have no reason for all of those top boat builders not to be using top end balsa instead of foams since balsa is cheaper.

[Polux]

Originally Posted by Dockhead

LOL. Mark circumnavigated in a Beneteau. Joke!!!

That joke I don't understand. Why it is a joke Mark having circumnavigated on a Beneteau (39ft)? I believe he posts on this forum. This is his blog:
http://www.ourlifeatsea.com/