Hull construction

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John

.
Jun 3, 2006
803
Catalina 36mkII Alameda CA
What do people think of the relative merits/disadvantages of fiber glass boats made with a solid hull vs. cored hull? (I understand that most fiber glass boats have cored decks; I'm talking about the hulls.) Thanks.
 

John

.
Jun 3, 2006
803
Catalina 36mkII Alameda CA
What do people think of the relative merits/disadvantages of fiber glass boats made with a solid hull vs. cored hull? (I understand that most fiber glass boats have cored decks; I'm talking about the hulls.) Thanks.
 
May 11, 2005
3,431
Seidelman S37 Slidell, La.
My Humble Opinion

While I guess there is something to be said for the stiffness of a cored deck, I would never want one, for a couple of reasons. First is the matter of thru hulls when you have a cored hull. It is my understanding that the proper way to do this is to make a solid glass area where the thru hull is installed. Don't know that this is actually done. The biggest factor for me is that if one were to hit something and knock a hole in it, the glass is much easier to repair. By this I mean easier to make a temporary repair until you can get to somewhere to make it right. If you do knock a small hole in a cored hull, apparently it doesn't take much moisture to cause the area to delaminate. I also believe that repairs to a cored hull would be much more expensive.
 
May 11, 2005
3,431
Seidelman S37 Slidell, La.
My Humble Opinion

While I guess there is something to be said for the stiffness of a cored deck, I would never want one, for a couple of reasons. First is the matter of thru hulls when you have a cored hull. It is my understanding that the proper way to do this is to make a solid glass area where the thru hull is installed. Don't know that this is actually done. The biggest factor for me is that if one were to hit something and knock a hole in it, the glass is much easier to repair. By this I mean easier to make a temporary repair until you can get to somewhere to make it right. If you do knock a small hole in a cored hull, apparently it doesn't take much moisture to cause the area to delaminate. I also believe that repairs to a cored hull would be much more expensive.
 
Oct 3, 2006
1,033
Hunter 29.5 Toms River
I'll disagree

That repairs on a cored hull are more expensive. You simply have to lay up the thin skin, stuff some foam/wood and resin on top, and then lay the outer skin. If it was more expensive, nobody would use it in the first place!!
 
Oct 3, 2006
1,033
Hunter 29.5 Toms River
I'll disagree

That repairs on a cored hull are more expensive. You simply have to lay up the thin skin, stuff some foam/wood and resin on top, and then lay the outer skin. If it was more expensive, nobody would use it in the first place!!
 
May 11, 2005
3,431
Seidelman S37 Slidell, La.
Brian, what about

Brian, there is a tremendous amount of difference between the manufacture of a cored hull and a solid glass hull, and the repair of each. Not being a fiberglass guy, nor an engineer, nor an expert in any boat manufacturing process, I could see it being less expensive to manufacture a cored hull than it is a solid one, being as resin is very expensive. Manufacturing cost was not the initial question. If you were to knock a small hole in a cored hull, how to you know how much moisture is between the laminate and the glass. Do you just ignore that possibility and slap some glass on, or do you start cutting it back till you are sure it is solid. Do you have to check with a moisture meter to find out. I have seen a foam cored deck that was damaged in a collision, and delaminated, not from moisture but from impact. It was not a pretty sight, and the damaged boat was sent back to the manufacturer to repair. And this was a deck. I'll stick to my origional statement that repair on a cored hull is more expensive, unless someone with some real expertise convinces me differently.
 
May 11, 2005
3,431
Seidelman S37 Slidell, La.
Brian, what about

Brian, there is a tremendous amount of difference between the manufacture of a cored hull and a solid glass hull, and the repair of each. Not being a fiberglass guy, nor an engineer, nor an expert in any boat manufacturing process, I could see it being less expensive to manufacture a cored hull than it is a solid one, being as resin is very expensive. Manufacturing cost was not the initial question. If you were to knock a small hole in a cored hull, how to you know how much moisture is between the laminate and the glass. Do you just ignore that possibility and slap some glass on, or do you start cutting it back till you are sure it is solid. Do you have to check with a moisture meter to find out. I have seen a foam cored deck that was damaged in a collision, and delaminated, not from moisture but from impact. It was not a pretty sight, and the damaged boat was sent back to the manufacturer to repair. And this was a deck. I'll stick to my origional statement that repair on a cored hull is more expensive, unless someone with some real expertise convinces me differently.
 
Oct 2, 2006
1,517
Jboat J24 commack
look at what the better boats do

A core will make a stronger hull at a given weight BUT it is all about how well it is done at the factory Doing it right puts the cost out of reach for any of the lower cost boats A J-24 hull is now in the 50000 dollar range Having seen many of them in race crashes The hull is so STIFF that it punches a nice small hole in a small local area that does NOT spread Tommays
 
Oct 2, 2006
1,517
Jboat J24 commack
look at what the better boats do

A core will make a stronger hull at a given weight BUT it is all about how well it is done at the factory Doing it right puts the cost out of reach for any of the lower cost boats A J-24 hull is now in the 50000 dollar range Having seen many of them in race crashes The hull is so STIFF that it punches a nice small hole in a small local area that does NOT spread Tommays
 

Ross

.
Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
First of all it depends upon the core material!!

There have been several books written on the merits of the core materials. Some are easily fractured and will delaminate from the fiberglass in a collision. Some are wonderful as long as they never get wet at which point they start to rot. (read that balsa) There are some core materials that bond well to the glass and are of such a tough nature that delamination is not a concern .( read about Corecell and Airex core) Very much like the windshield on a modern car. The glass is bonded to an elastic membrain that stretches on impact but doesn't disentigrate.
 

Ross

.
Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
First of all it depends upon the core material!!

There have been several books written on the merits of the core materials. Some are easily fractured and will delaminate from the fiberglass in a collision. Some are wonderful as long as they never get wet at which point they start to rot. (read that balsa) There are some core materials that bond well to the glass and are of such a tough nature that delamination is not a concern .( read about Corecell and Airex core) Very much like the windshield on a modern car. The glass is bonded to an elastic membrain that stretches on impact but doesn't disentigrate.
 
Feb 6, 1998
11,759
Canadian Sailcraft 36T Casco Bay, ME
Our story..

About 8 years ago my wife and I wanted a %&% 38 (brand left out so I don't start any wars) and and decided that was the boat we were going to buy. We located about a half dozen and began looking. We found one we really liked, in apparent bristol condition, made an offer, and proceeded with survey. On our first visit to the boat I had my own moisture meter with me but it was well below freezing and moisture meeters don't work, to detect moisture, when everything is frozen. So one warm day in late April we surveyed and started with the hull. The stbd side from the leading edge of the keel about six feet back was soaked! The area in question was no less than 18 sq feet of wet core! The port side was in similar shape and areas of about two feet in diameter around two of the many thru-hulls were also soaked. After convening with the surveyor we stopped the survey and I paid the guy for the time he spent. That boat was still on the market almost two years later... I spent the next three weeks looking at four more %&% 38's and each and every one needed serious, to the tune of up to five figures, below waterline repair/re-building! This brand was and is considered to be a very high quality boat by most all sailors but wood below the waterline can and will eventually get wet if not properly maintained or cared for. All it takes is for a soft or hard grounding to delaminate the skins. Once you have below waterline delam then internal condensation can occur even without an external water leak. Compound onto that winters below freezing and the fact that water expands as it freezes & and the problem grows and grows until you pull out the greenbacks and fix it.. That being said, I put my meeter to 4 Hinterholer Nonsuchs' about 18 months ago and only one had any serious core moisture. While one in four is not bad, it's still not good considering how expensive those fixes are. It just goes to show that even high quality cored boats can have problems. Vacuum bagging a cored hull is the best way to ensure a solid cored hull to limit delam, and it's my belief that they do hold up better, but they are EXPENSIVE to build!!! Most of the used boats on the market will be hand laid which can leave tiny pockets or voids where condensation can begin it's evil path.. After my own experiences with cored hulls I decided to stick with solid glass! If you're racing cored is lighter if you're cruising my vote is solid....
 
Feb 6, 1998
11,759
Canadian Sailcraft 36T Casco Bay, ME
Our story..

About 8 years ago my wife and I wanted a %&% 38 (brand left out so I don't start any wars) and and decided that was the boat we were going to buy. We located about a half dozen and began looking. We found one we really liked, in apparent bristol condition, made an offer, and proceeded with survey. On our first visit to the boat I had my own moisture meter with me but it was well below freezing and moisture meeters don't work, to detect moisture, when everything is frozen. So one warm day in late April we surveyed and started with the hull. The stbd side from the leading edge of the keel about six feet back was soaked! The area in question was no less than 18 sq feet of wet core! The port side was in similar shape and areas of about two feet in diameter around two of the many thru-hulls were also soaked. After convening with the surveyor we stopped the survey and I paid the guy for the time he spent. That boat was still on the market almost two years later... I spent the next three weeks looking at four more %&% 38's and each and every one needed serious, to the tune of up to five figures, below waterline repair/re-building! This brand was and is considered to be a very high quality boat by most all sailors but wood below the waterline can and will eventually get wet if not properly maintained or cared for. All it takes is for a soft or hard grounding to delaminate the skins. Once you have below waterline delam then internal condensation can occur even without an external water leak. Compound onto that winters below freezing and the fact that water expands as it freezes & and the problem grows and grows until you pull out the greenbacks and fix it.. That being said, I put my meeter to 4 Hinterholer Nonsuchs' about 18 months ago and only one had any serious core moisture. While one in four is not bad, it's still not good considering how expensive those fixes are. It just goes to show that even high quality cored boats can have problems. Vacuum bagging a cored hull is the best way to ensure a solid cored hull to limit delam, and it's my belief that they do hold up better, but they are EXPENSIVE to build!!! Most of the used boats on the market will be hand laid which can leave tiny pockets or voids where condensation can begin it's evil path.. After my own experiences with cored hulls I decided to stick with solid glass! If you're racing cored is lighter if you're cruising my vote is solid....
 

John

.
Jun 3, 2006
803
Catalina 36mkII Alameda CA
vacuum bag

A friend of mine is looking at a CS 40, built in 2001. I was under the impression that CS had gone under in the 1990s, but I guess not, or else they restarted again. In any case, it's a vacuum pack, cored hull. This is why I'm asking. Does anybody know anything further about this make of boat? Thanks.
 

John

.
Jun 3, 2006
803
Catalina 36mkII Alameda CA
vacuum bag

A friend of mine is looking at a CS 40, built in 2001. I was under the impression that CS had gone under in the 1990s, but I guess not, or else they restarted again. In any case, it's a vacuum pack, cored hull. This is why I'm asking. Does anybody know anything further about this make of boat? Thanks.
 

RobG

.
Jun 2, 2004
337
Ericson 28 Noank, Ct
Maine Sail

I sure would like to know what boat your referring to. How about a list of several you know of with cored hulls? I'm starting my 4 year plan to move up to a 30ish footer and want to avoid this. Thanks.
 

RobG

.
Jun 2, 2004
337
Ericson 28 Noank, Ct
Maine Sail

I sure would like to know what boat your referring to. How about a list of several you know of with cored hulls? I'm starting my 4 year plan to move up to a 30ish footer and want to avoid this. Thanks.
 
Sep 20, 2006
2,953
Hunter 33 Georgian Bay, Ontario, Canada
CS Yacht International

John, from the CS owners web site In 1999, CS Yachts International began production again on a limited basis. An e-mail in 2005 informed us that: "You should note that CS is in business and have delivered the first of the new CS Power Cat 42's and have orders for more. In addition Carlson & Wentzell Marine Inc. have started marketing the 363, 393 and the Custom 44 sailing yachts in addition to the Power Cat 42 in Atlantic Canada and Bermuda." Check the link above to their web site for current status. And the new web site http://www.csyachts.com/sail.htm
 
Sep 20, 2006
2,953
Hunter 33 Georgian Bay, Ontario, Canada
CS Yacht International

John, from the CS owners web site In 1999, CS Yachts International began production again on a limited basis. An e-mail in 2005 informed us that: "You should note that CS is in business and have delivered the first of the new CS Power Cat 42's and have orders for more. In addition Carlson & Wentzell Marine Inc. have started marketing the 363, 393 and the Custom 44 sailing yachts in addition to the Power Cat 42 in Atlantic Canada and Bermuda." Check the link above to their web site for current status. And the new web site http://www.csyachts.com/sail.htm
 
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