Most boats have liners; which ones do it best?

[avb3]

Originally Posted by HappyMdRSailor

Did you guys see minaret's post on the failed survey thread???

Delam liner at the step...

Frightening...

And that was in a Catalina 42 with much better access to the grid than a beneteau. Still had to cut several very large holes in the liner to provide enough access to debonded areas of grid/liner. Anyone who can remove all interior cabinetry in way of repairs, tent the entire vessel interior for dust control, vessel protect soles, remove teak/holly insets on liner sole, cut out all liner under insets, grind and glass all areas of delam (almost impossible to reach), rebond liner skins, grind and glass all seams, fair out, prime & prep, color match gelcoat, gelcoat and finish interior to match, remove all masking and vessel protect, clean entire interior; all for $200, has a job waiting here in Seattle. This one was not too bad, passed at least two surveys like that before being spotted by diligent yard crew. Have yet to see a liner delam repair which didn't require a similar process. Definitely not a DIY repair. Wouldn't suggest anyone but an experienced pro tackle this sort of repair. And yes, materials costs alone far exceeded that amount.

(copyrighted material 11-1-15, minaret, yacht grunt and artist extraordinaire)

Yes, I actually did read that, and it triggered the thought for this thread. I was hoping Minaret would chime in; I may shoot him a PM asking him to. His input is always, always valuable.

[Boatyarddog]

Mariners generally use wood Bulkheads to maintain structure, with flanges attached to them that have liners incorporated to support settes and floor components.
The liners are "tabbed in" at points to add stabilization and stiffness to the hull.
The bulkheads support those areas that stress the most.


Sent from my iPad SV Cloud Duster

[HappyMdRSailor]

Originally Posted by avb3

Yes, I actually did read that, and it triggered the thought for this thread. I was hoping Minaret would chime in; I may shoot him a PM asking him to. His input is always, always valuable.

Don't go swellin' his head now!

(if I added up all of the time he's spent on detailed advice + time I saved heeding it + $$$ saved by not doing something wrong = incalculable)

(is there a way we can privacy screen or censor which threads or posts minaret can see???) ....

I say the "liner boat" with the proven performance and reliability is just as good, if not better than a stringer and sole boat...

[a64pilot]

See, I'm going to bet that a liner or grid type boat is fine, actually can be stronger, and stiffer with less weight, it's all good.
Until you need to fix something, then your going to wish it didn't have that liner or grid.

I'm separating liner from grid as I would think they can be different things, I'm thinking a liner isn't really all that structural, and a grids whole purpose is structure?

Yeah, we need someone who isn't guessing like I am to chime in and set us or me straight

[Geitz]

FWIW: My 1999 Jeanneau Sun Odyssey 36.2 does not have a hull or deck liner.

[Dockhead]

You said you didn't want to discuss the pros and cons of liners. But maybe you would like to hear about production boats without them?

Jeanneau starting using them only 10 or 12 years ago, AFAIK. Pre-liner Jeanneaus are really nicely built and good sailing boats, compared to other mass produced boats.

I would really avoid a linered boat if you possibly can. Here's my logic: If you're buying new, you're getting the benefit of the liner -- namely, a significant reduction of cost. You can sell the boat on before you start to have the kind of maintenance problems which liners create. In my opinion, that makes perfect sense. But buying a linered boat used -- on the cusp of those issues which are so complicated by liners -- that seems like a bad deal, if you have a choice of buying a boat without a liner.

I would even go for an older, higher end boat. As always -- the best deal is one which has just been extensively refit by someone else, who will not recover the cost he sunk into the refit.

[Dockhead]

Originally Posted by reed1v

This site use to be about "cruising" sailboats. If your going cruising long distances, you really need quick access to the hull for many reasons. Most sailboats built commercially since 2000 are for day sailing or club events; not long distance cruising. Liners make pretty boats inside but are not functional for those folks doing serious seafaring. . .

The OP didn't want to talk about it, but here we are.

I have just been through a collision in my boat. A fishing boat pranged me at anchor at night. The fisherman didn't have insurance.

If my boat had had a lightly built uncored hull, and had my boat had a liner, it would probably be totalled. Worse, the hull would probably have cracked, and the boat would have sunk, since you couldn't get to the inside of the hull with a linered boat.

As it was, I had instant access to the inside of the hull to check for a breach, and could have patched it if there had been one.

The damage can be repaired because it is immediately accessible. The stick built furniture (wet locker on one side of the bulkhead; washing machine cabinet on the other) can be popped right out to do the work. I just got the estimate -- 5,440 pounds, less than $10,000, from one of the best boatyards in the Solent. Most of that is teak work. To repair damage caused by a 50 ton fishing boat t-boning me. A linered boat would probably be at the bottom of the Solent right now.

You might never need the strength and repairability of a conventionally built, fully cored, unlinered hull. But when you need it -- boy, you REALLY need it.

[neilpride]

Huge diference is in the way they are build it , this days almost any boat builder is using some kind of liner structure or grid system, to me for offshore work a liner have no place....

[Azul]

Originally Posted by Dockhead

The OP didn't want to talk about it, but here we are.


If my boat had had a lightly built uncored hull, and had my boat had a liner, it would probably be totalled. Worse, the hull would probably have cracked, and the boat would have sunk, since you couldn't get to the inside of the hull with a linered boat.

You might never need the strength and repairability of a conventionally built, fully cored, unlinered hull. But when you need it -- boy, you REALLY need it.

I agree with your premise that a boat without a liner is safer if involved in a collision for the reasons you state, however I think your statements about cored hulls are controversial. For example, coring a hull doesn't make it "stronger," rather it makes it stiffer. An uncored hull will absorb the same impact as an uncored hull, but it will deflect more which can actually be an advantage the same way an impact absorbing bumper on a car avoids damage in low speed accidents. Many purists would make the case that having a cored hull below the waterline is a potential disaster, and I have read numerous accounts lately of high end boats with horrible delamination problems from having a cored hull.

From FIBERGLASS BOATBUILDING: Cored Laminates

Depending on how thick the core of the sandwich is, the outer skins can be quite thin indeed. On a boat, however, there are practical limits, as the skins must at least be thick enough to resist ordinary impacts. As a general rule, as the lightweight core gets thicker, the relatively heavy skins can get thinner, and the whole structure gets stiffer and lighter. The larger the structure, the greater the weight savings relative to a solid structure of similar size and strength. For boat hulls the practical minimum limit is about 30 feet. On any boat shorter than this, the skin thickness needed to resist impacts is so great relative to the core’s thickness that there is no appreciable weight savings.

Another great benefit of cored hull laminate is that it provides great insulation. If you have ever cruised in cooler climates aboard a solid glass boat in the early spring or late fall and have awoken to rivers of condensation pouring off the overhead, you will appreciate the importance of this. A cored hull is always drier than a solid hull and is less likely to become a mildew farm. It is also warmer when it’s cold outside, cooler when it’s warm outside, and quieter as well.

Cored laminates do have some disadvantages and are in certain ways more fragile than solid laminates. There is no way to create a chemical bond between a core and its skins; instead the bond must be primarily adhesive. The best methods are either to lay up the core between two resin-rich layers of chopped-strand mat or glue the core in place with a resin-based adhesive putty. But even when a cored laminate is laid down with scrupulous care, it is more likely to delaminate than a solid one, particularly after suffering impact damage, whether the outer skin is punctured or not. In such cases, though there may only be a small area where damage is visible, the core will likely have separated from its exterior skin over a much larger area. Furthermore, the extent of delamination, however it occurs, can be difficult to ascertain if the core remains in close contact with its skin, as is often the case.

Cored laminates are also more susceptible to water damage. Any underwater core will eventually be invaded by some small amount of moisture migrating through its exterior laminar skin. Any puncture in the outer skin, no matter how small, will also readily admit moisture. If the puncture is underwater, even the speediest repair cannot prevent some saturation from taking place. This is why some builders insist on building only solid hulls and others will core a hull above the waterline, but never below it. Many cruisers believe no serious cruising boat should ever have cored laminate below its waterline; others believe a lighter hull is worth the risk of having to make more expensive repairs after a collision.

[Azul]

Here is a good discussion of problems with cored hulls which is very educational:

Marine Surveying : Composits - High Tech Materials in Boat Building

[TeddyDiver]

Originally Posted by Azul

and I have read numerous accounts lately of high end boats with horrible delamination problems from having a cored hull.

That's a common problem with unskilled core layup within mould build boats. However with proper methods and materials it's not an issue anymore, or even better control of the layup is achieved with one-off construction where the skins are laminated over the core.

BR Teddy

[ColdEH]

I have no liners or grid on my boat , thankful for that . I can lift the floor board in the forward cabin look under and see under the entire floor , every thing is easily accessible, tanks, thru hulls, etc . One thing nobody has touched on , the boats without liners/grids smell better , there are no trapped unventilated ares under the cabin sole . If you get a spill of any thing you can just wipe it up . Also adding anything to the boat like watermakers is made much easer .

Regards

[Azul]

Originally Posted by TeddyDiver

That's a common problem with unskilled core layup within mould build boats. However with proper methods and materials it's not an issue anymore, or even better control of the layup is achieved with one-off construction where the skins are laminated over the core.

BR Teddy

Your citations? Did you read the articles?

[TeddyDiver]

Originally Posted by Azul

Your citations? Did you read the articles?

I'm a boat builder and a designer so it's a part of my knowledge. Yes I did read them thou I've found books and studies as a better source of information than most articles.

BR Teddy

[Azul]

Originally Posted by TeddyDiver

I'm a boat builder and a designer so it's a part of my knowledge. Yes I did read them thou I've found books and studies as a better source of information than most articles.

BR Teddy

And I am trained as a scientist, and therefore reluctant to form opinions based on other's anecdotal information especially without references or an explanation.

It's pretty easy to get into boat building, but pretty hard to do it well and actually make money at it. That is one reason there is a paucity of supervision over the less skilled laborers forming laminations.

So, in your personal experience, it is your opinion that cored hulls are no longer a problem, ie not controversial? Have you done any research into core materials? Have you done a large number of insurance surveys on damaged boats?

We can let other readers review the following credentials and make up their own minds whether "high tech" composite cored hulls are an advantage over solid hulls or not. As the author points out, probably a great deal for the original buyer that benefits from the light weight but is not around for the problems that occur years or decades later.

Biography
David Pascoe has performed over 5,000 marine surveys, both pleasure craft and commercial.

He was born in Cleveland, Ohio where he began training as a marine surveyor with his father's firm of Lovell, Pascoe & Botton at the age of sixteen. There, he trained in pleasurecraft and commercial marine, as well as general insurance adjusting in the years 1965 through 1972. He gained experience with yachts, cargo - including commodities, and bulk cargoes - as well as CGL and seaman's injury claims. In 1971 he was appointed as a Correspondent to the American Institute of Marine Underwriters and was certified by the National Association of Marine Surveyors in 1973.

The firm opened a Fort Lauderdale office where he was transferred in 1972 and developed a specialization in yachts. He spent several years as an Official Measurer for the North American Yacht Racing Union and then spent two years studying with the Westlawn School of Yacht Design. He crewed extensively on the ocean racing circuit, including the notable maxi-racers WINDWARD PASSAGE and SOUTHERN STAR.

Among his major construction projects were the supervision of the 106' Denison "ASTRA DEE," the 96' Broward "FELICITY" and 98' Custom yacht "BLACK SHEEP." In addition, he has been involved with refits on numerous smaller boats and yachts.

His work has led to extensive travels throughout the U.S. Bahamas, Caribbean, South America and to Japan and the Pacific Rim where he performed survey work for a major Japanese Company.

David Pascoe has been a guest lecturer at Florida International University on the subject of marine surveying in 1989 and 1990 and is the author of many magazine articles over the years. He traveled to Japan in 1993 at the invitation of Nippon Ocean Racing Committee (NORC), where he gave an address titled "Marine Surveying in the U.S."

He is a former South Atlantic Regional Vice President of the National Association of Marine Surveyors.

David Pascoe is the author and publisher of books: "Surveying Fiberglass Power Boats" (2001), "Buyers' Guide to Outboard Boats" (2002), "Mid Size Power Boats" (spring 2003) and "Marine Investigations" (Nov. 2004).

In September 2005, "Surveying Fiberglass Power Boats" 2nd Edition was published.

In 2012, David Pascoe has retired from marine surveying business at age 65.

Last updated March 25,2014.