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  #21  
Old 06-13-2012
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Re: De-watering wet core

WDS,

No the fiberglass portion of the boat will weight significantly more was my point. I have no idea what the glass schedule and core of a Schock 35 is. And your ushers are assuming that everything besides the boat weigh nothing. Engines, electrical, mast, sailing gear, cabinetry, ect all add significantly to the weight of a boat. I just used nice round numbers to make the math easy.
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Old 06-13-2012
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Re: De-watering wet core

"quite a lot of wet core throughout" is really sad to hear. It would be a miracle to address a single small section, without ripping her open. Significant core damage is not going to be repaired without serious surgery. No way, no how. Worse, a proper repair could be a serious percentage if not the entire the value of your boat.

What caused the ingress? That needs to be fixed too.

Sorry to hear of this trouble.
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  #23  
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Re: De-watering wet core

Greg,


A cored hull ( which is the only item here in question ) will weigh more than a solid hull - however, as you point out the hull is only a small portion of the total displacement of a S/V.
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Old 06-13-2012
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Re: De-watering wet core

Quote:
Originally Posted by WDS123 View Post
Greg,


A cored hull ( which is the only item here in question ) will weigh more than a solid hull - however, as you point out the hull is only a small portion of the total displacement of a S/V.
No way, maybe in Schock boats but other properly designed hulls with a core will be stiffer and lighter then the same hull made in solid construction. look at any modern Racing sailboat and you will not find any solid hulls. This is why cored hulls were developed. the idea is to use less glass and the light weight core for stiffness resulting in a stiffer and lighter hull.
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Re: De-watering wet core

Sigh ;


A cored hull will be lighter than a solid hull - agreed

Stiffer - it depends on complete boat structure, not a black or white answer. Ie - How is sump built ? C&C back in the 1980s had some notoriously flexible sumps. A theoretical stiff hull layup is for naught if the keel is flopping back and forth.

Durable ? - This thread illuminates the 'core' question ( excuse the pun ) for most sailors. A solid hull will never have a wet core or a rotted core. The sacrifice of a few pounds in hull weight is far outweighed by the increase in duribility for 90% of boar owners.


Cheaper ? - a cored hull is almost always less expensive to build


Schock builds both cored and solid depending on the expected use of the of the boat.

for example, the Schock 40 has a foam core because it is a flat out racing machine where weight was the primary consideration - how many 7,500 lb 40ftrs are out there ? the owners of Schock 40s know they are operating a Formula One racer. there are very few owners who really need a flat out stripped racing machine.

On the other hand, our Daysailer owners want a boat that is performance oriented but also wants not to have to worry too much about maintenance. So, the boats are designed and built with low upkeep and durability as a primary consideration. Solid Hulls with Vinylester resin is a good solution for our Daysailer customers.

Last edited by WDS123; 06-13-2012 at 01:33 PM.
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Re: De-watering wet core

Boats Cored below the waterline are NOT going to make it into the old boat hall of fame



With about a 3 to 4 mm outer skin on a J24



And pretty much the same on a J160 the water just does NOT have to go very far to find core below the waterline

I pulled the J160 outer skin OUT of a PILE of jackstands that it fell ON



J80 that left the keel in LIS

Its freaking hard enough to keep a deck core dry that spends 99% of its time well DRY
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Old 06-14-2012
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Re: De-watering wet core

Balsa. Some smaller areas have de-laminated.
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Re: De-watering wet core

Do an Internet search. It's a fairly common practice even by some boatyards.
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Re: De-watering wet core

Here's a link to the 97 page fiberglass repair manual online by West Systems. Describes a lot of the methods posted on this thread. Thanks for recommendations.
http://westsystem.com/ss/assets/HowT...aintenance.pdf
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Old 06-14-2012
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Re: De-watering wet core

Quote:
Originally Posted by Stumble View Post
The problem with solid glass layup is that regardless (not completely, but close) of the material a structure needs to be a certain thickness in order to provide reasonable stiffness. And fiberglass is heavy, really heavy, tremendously heavy, while core materials are very light weight.

So let's say you need a one inch thickness to get the required stiffness, making that out of fiberglass Will require nominally 25 layers of 24oz glass, with a weight per square foot of .33lbs/sq foot per layer. So 8.25lbs/sq foot of deck.

A cored deck however at one inch thick Would likely use a .75" thick core, with .125 inch skins. The nominal weight then of the skins would be .925 lbs/sq foot plus the core at .5lbs/sq foot (for balsa). So our cored deck weighs in at roughly 2.35lbs/sq foot. Or a little over 1/4 the weight of the uncored deck.

The right answer is not to refuse to use cores, but to treat them properly to prevent core rot problems.
No-one makes a solid laminate deck for the reason you cite but solid hulls with stiffeners like hat sections, bonded in bulkheads & furniture etc. easily make a hull stiff enough when you factor in the compound shapes (the egg effect). I would venture to say that the vast majority of glass boats out there are single skin glass with a cored deck.
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