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Old 05-05-2009, 14:16   #1
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Foam-Cored Hulls!

Have searched this forum, read Pascoe warnings and here is a quote:

offered in state-of-the-art vacuum bagged, hand laid construction. We know of no better way of building a light, strong boat. The gel coats we specify are isophthalic blends. The important skin coat is Vinylester.

Is this balsa core or is foam core different?


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Old 05-05-2009, 15:04   #2
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"just say no" to cored hulls of all types :>) Decks are bad enough. Just not worth the risk, unless you are just wanting to race it for a year..... then buy another!
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Old 05-05-2009, 16:23   #3
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EJC

The statement is about the gelcoat and is more about blistering I believe. Wouldn't matter whether the core is foam of balsa.

And my 21 year old boat hull is cored and doesn't have any problems. Don't any deck core problems either, but do have some leaking fittings that I need to rebed before a core problem develops. My biggest problem is with lexan windows!
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Old 05-05-2009, 16:56   #4
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Quote:
Originally Posted by Don Lucas View Post
EJC

The statement is about the gelcoat and is more about blistering I believe. Wouldn't matter whether the core is foam of balsa.

And my 21 year old boat hull is cored and doesn't have any problems. Don't any deck core problems either, but do have some leaking fittings that I need to rebed before a core problem develops. My biggest problem is with lexan windows!
My biggest problem is assimilating all this information to make a proper decision! This boat research is not for the faint of heart!

So many pros and cons and choices. Am narrowing down my search to two boats and am leaving for N Carolina this weekend to see two more boats.

Again thanks for the input.
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Old 05-05-2009, 17:17   #5
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Foam core construction done right is very, very good, but much more expensive and labor intensive than single skin construction.

Simply put, it is important that, in the construction process, every hull and deck penetration is anticipated and the core deleted in this area. You really don't even want any screws through the inner or outer skin. I've seen delamination caused by ties for wiring courses screwed to the inner skin along the bilge. If water can find a way, it will.

If the builder does not delete core, or if someone decides to move a deck fitting, unless you go to the hassle of gouging or reaming out the core and replacing it with thickened epoxy, any failure of bedding compound will allow water into the core.

I would have no qualms about a well made, well maintained foam core hull and deck.
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Old 05-05-2009, 17:23   #6
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A good cored hull is possible for sure, especially with todays techniques. It has to be a "for sure" thing that everything went according to plan though. Problems: 1) A fitting was put in (above or below the waterline) that was not in the plan at the layup schedule. ie:buyer added something after layup. 2) The layup at the core is too dry, the core doesnt bond to the hull skin either inside or outside, or both. This is pretty common on older boats too. It represents as a different sound when the surveyor "sounds" the hull. As a cored hull requires a bonded sandwich to create the rigid strength planned, this is considered a defect.
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Old 05-05-2009, 20:35   #7
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EJC,

You might find Bob Perry's consulting service helpful. I used him for advice on my last boat purchase - interestingly enough because I had a specific concern about buying a boat with a cored hull. His conclusion - he had high confidence in both the designer and the engineering firm that had specified and overseen the composite layup in the boat. Money well spent.

Robert H Perry Yachts Designers Inc. - CONSULTATION SERVICE

By the way, something often left out in core warnings is that a well built cored boat should be more seaworthy than an equally strong identical single laminate boat. That's because the considerable weight saved by using a core can be put low in the keel to make the boat stiffer and improve stability.

Carl
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Old 05-05-2009, 21:03   #8
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Quote:
he had high confidence in both the designer and the engineering firm that had specified and overseen the composite layup in the boat.
All core construction is complicated. Being good at something matters and the details do matter too. Well completed cored hulls are still running around solid after many years and they include balsa cores. There seems to be a general idea that some technologies are just plain bad without considering that many technologies can be screwed up when you get sloppy about it. All the complex materials in boat building have that element to them at almost every junction. High tech materials take extra effort. The extra weight in non cored hills does have evidence that the over built boats are not stronger. The momentum of the heavier boat requires more strength to support it's deceleration. This isn't just a simple debate about what method of construction is better or worse. Most all methods well executed have long track records.

Foam mitigates moisture the migration of issue of balsa at the expense of being a PITA to work with. It presumes that the easier balsa process is hard to to perform well when it probably isn't. It's only in the hand laid made to order premium boats that this even gets to be a possible debate to get the level of quality you you want. The QA and process required to assure such performance is not cheap if you expect the proof it was done right. So it comes down to proving it was done right.

The track records seems to show boats done right last a heck of a long time.
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Old 06-05-2009, 09:04   #9
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It's kinda like shooting the apple on someones head with a bow and arrow...... as long as you hit the apple everytime things are great! It's really all about engineering and then meticulous implementation. Buy a cored boat from a small company with limited resources? No way. Buy a cored boat built by someone like TPI? maybe.
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Old 06-05-2009, 09:13   #10
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Hulls from poorly designed boats or poorly constructed boat (or both) have delaminated in a couple of years. (re: Bumfuzzle) On the other hand as Paul has mentioned, well designed and constructed boats keep going and going. It truly is a crap shoot.

Is this a new build? How long will you keep the boat? Who's the manufacturer? Is this a Cat or a monohull?
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Old 06-05-2009, 09:14   #11
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From above:"...something often left out in core warnings is that a well built cored boat should be more seaworthy than an equally strong identical single laminate boat. That's because the considerable weight saved by using a core can...."
"Should be" is the key in that statement.The trouble with this theory is : How thin an outer layer is OK for your boat? Once you crack it your core is saturated. Most the uncored boats I've seen are 1/4 to 3/8" above the waterline.... depending on the size of the boat. How thin are you willing to go? 1/8"? The cored 44 footer I owned had core saturation and core separation, I eventually had it repaired and repainted (>$40K), fortunately the outer skin was pretty much the same as any uncored boat (5/16 to 3/8" thick).... This is the "Implentation" part that most builders cant control..... I'm glad they didnt control mine!
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Old 06-05-2009, 09:30   #12
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People used to look at me, with my wooden boat, and say, "boy, whata lotta work you got there." Then I saw my first plastic boat with a rotten deck. I just laughed. Best of both worlds? Rot on the top & blisters on the bottom!

I was once on the hard and looked across the yard at my boat - she's a beauty. She was sitting next to a steel boat and a fiberglass boat &, I swear this is true, I looked over and my wife was pounding cotton into our seams, the steel boat guy was grinding rust, and the FG guy was grinding blisters with a dremmel tool. Side by side. At the same moment. And there I was with no camera!

Moral of the story? Pick your poison. You're going to work on her no matter what she's made of.
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Old 06-05-2009, 11:29   #13
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Hulls from poorly designed boats or poorly constructed boat (or both) have delaminated in a couple of years. (re: Bumfuzzle) On the other hand as Paul has mentioned, well designed and constructed boats keep going and going. It truly is a crap shoot.

Is this a new build? How long will you keep the boat? Who's the manufacturer? Is this a Cat or a monohull?
The boat is a Nimble (Ted Brewer design) 30' made by Nimble Boat Works!

Seems to fit my needs. Will keep it as long as I am able. Plan on taking 1 or two week cruises up and down the ICW between Beaufort and Georgetown SC and docking in Charleston SC. No ocean travel!

I love to fish and camp out. Living aboard is a dream but not practical for me! This boat is trailerable, so when hurricanes arrive....away we go as I have done numerous times!

I cannot thank every one enough for your input!

So what do you think of this manufacturing company and their quality?
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Old 06-05-2009, 12:51   #14
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I don't know a thing about them, maybe someone else can offer an opinion. For what it's worth, I would think that a cored hull is a non issue in a trailer sailer.
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Old 06-05-2009, 20:05   #15
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So, a badly designed or badly built cored hull is no good. Gee, that's a surprise! Now, who's gonna be the first to write that a badly designed or badly built non-cored hull is good? Or is everyone gonna agree with me that those are no good either?

IMO, cored hulls got nothing to do with shooting apples on peoples heads; if they are build or designed bad, it's just that: bad, but if they are designed and build good, they are far superior to "solid glass" hulls. I agree that there are builders that don't have the knowledge to build good cored hulls. There are also builders that don't have the knowledge to build good hulls in any form or material so it's up to the buyer to check it out, ask others who own the same design about it etc.... regardless of material used or cored or not.

This whole issue is mostly watering hole talk and in the same category as fin vs full keel or balanced spade rudder vs skeg-hung rudder. There's no doubt that fin keels and balanced spade rudders are better performing... as long as they stay attached to the boat. Remember that the reason for full keels and attached rudders was that this was the only way they could build a strong enough boat. Wake up call, times have changed, we can now build hulls that can have fins and spade rudders and are ten times as strong as any full keeled boat like they used to build. What todays ocean racing crews put their boats through is just unbelievable and no wooden full keeler would survive that for even 10 minutes, let alone around the world in a couple of days. Sure some loose their keel/mast/rudder etc. but that's no proof that modern designs are not good... it's amazing even if some of them don't disintegrate while carving through 30 foot waves at 40 knots... just try to imagine being a hull and driven like a bat out of hell through that. Guess what... they are cored hulls!

Yep, Jedi is fully balsa cored and dry as a bone after 15 years. Build by TPI using the SCRIMP process. There are many other builders doing a great job. Sales talk like "we only build proven solid glass boats" just means that they can't afford innovation, modernization or don't have the skills for it.

cheers,
Nick.
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