What core?

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Whimsical
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What core?

Post by Whimsical » Sun Jun 28, 2009 9:48 pm

I did some research before going with the balsa and found a lot of info on the problems with foam. Schionning wanted about 10% more for the foam kit, not a lot so it wasn't the cost that put me off.

Treat foam the same as balsa in every way and don't think you can just cut holes to mount something or ever use a screw into anywhere. Everything must be finished to the same level as balsa, including the edge treatments for every hole.



Mike

judy
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What core?

Post by judy » Mon Jun 29, 2009 12:30 am

whingeingpom wrote:what might happen to balsa if (when?) water gets into the core.


I can point to an example of what happens when water gets into balsa. John and Nancy purchased and sailed back to Australia a second-hand Leopard 42 from the Caribbean. Recently they hauled it out for repairs in Mackay and inspected the leaky above-waterline through-hulls, to find they had been installed without first sealing the balsa core. This was a professional build, mind you - so wtf were the builders thinking?!



John has made the appropriate repairs. What gives me heaps of confidence in balsa, is the fact that despite the shoddy workmanship, the water only travelled and rotted the balsa to a depth of 1cm.



You can read about it on John's blog here: http://www.blognow.com.au/jenksie/13797 ... 00509.html

44c
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What core?

Post by 44c » Mon Jun 29, 2009 3:58 am

Exactly the kind of shoddy construction that gives a core material a bad reputation it doesn't deserve. And "professional" builders would be the worst offenders.

whingeingpom
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Location: Caribbean

What core?

Post by whingeingpom » Mon Jun 29, 2009 7:46 am

That's an interesting article at yachtsurvey dot com, 44C, thanks, although that particular guy obviously doesn't like any type of core very much and prefers good solid fibreglass which is fine for the power boats he mentioned. I found another interesting article about balsa (although not balsa cored Duflex). As a deckhand / newbie I'm not allowed to post hyperlinks but if you Google "balsa core compost" you'll find it.

44c
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What core?

Post by 44c » Mon Jun 29, 2009 5:58 pm

No doubt you can find hundreds of articles about rotten balsa cores.



There have been thousands of boats built with balsa cores, maybe tens of thousands. And as Judy pointed out, even the "professionals" didn't always do it properly. Some of those boats would be 30-40 years old now, and the majority of them are fine.



But nobody is denying that balsa can rot if you build wrongly. People DO say that foam won't take up water, and won't give any trouble if it gets wet, and that is false.



In balsa cored Duflex any water shouldn't spread far, there are solid epoxy barriers every 100mm or so. Which may actually be an advantage that foam cored Duflex doesn't have.

judy
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What core?

Post by judy » Tue Jun 30, 2009 1:03 am

whingeingpom wrote:As a deckhand / newbie I'm not allowed to post hyperlinks but if you Google "balsa core compost" you'll find it.
I think this is the article:
http://www.pcmarinesurveys.com/balsa%20 ... rveyor.htm

The last paragraph says it all:
So, can a quality boat be built with a balsa bottom ? Yes they can and are but it requires great care and attention to details like relieving all balsa in areas with deck fittings, throughulls or even just screws.
Boats are built with balsa because it can be cheaper (maybe not if you do it right) and lighter than achieving the same initial strength with solid FRP. Are you willing to bet that your builder wants to build cheap but then pays the extra attention required to do it right.


If you ask me two questions:



What hull material would you consider as an owner-builder?

What hull material would you consider if buying an existing boat?



...I would give two different answers.

gunnadoo
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What core?

Post by gunnadoo » Sun Jul 19, 2009 12:48 am

Just to add a bit of interest - I built a 3 metre tender using polycore about a year ago. I used polypipe from the local hardware in a few places. So far, very impressed. The poor little thing is not getting an easy life - Painted with single pack, treated with not a huge amount of TLC. In short, I am trying the material out. By the way, I have no vested interest in pushing the product, I am just another boaty looking for a better way. So far, the things I like are - light weight, low cost (about on par with ply), NO ROT PROBLEMS (yes, that is my pet hate), very easy to work (cut with a stanley knife) or fine angle grinder if glassed, bends easily, better with careful use of a hot air gun. Did I mention rot free? Floatation - each of the honeycombs is an air pocket. Dislikes - working edges - needs filling or an edge glued on, and lack of designs - there may be good reason for this. How does it compare to other foams or duflex? I simply dont know in many aspects, as I have not used them, but I do know that it does have some good points, so I think that the product is worthy of inclusion in this discussion.

whingeingpom
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What core?

Post by whingeingpom » Sun Jul 19, 2009 7:45 am

What is Polycore and Polypipe?

Finally
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What core?

Post by Finally » Sun Jul 19, 2009 10:09 am

First up - Hi to everyone - my first post.



Gunnadoo - interesting that you have been "testing" the polycore and that it has stood up pretty well. I have actually bitten the bullet and will be taking delivery of a Pacific 40 kit probably in September. The hull shoes (premade) are infused foam whilst the rest of the kit is mainly polycore laminate. A bit of a leap of faith from my point of view as the product is relatively unproven but I am looking forward to the challenge. Preparation of the edges with filling or glassing over would be required with any composite material (balsa, foam or polycore) whether or not polycore is easier that the other alternatives for this, I will soon find out.



Whingeingpom:

A couple of places you can check. Obviously from my point of view, search on Pacificmultihulls (I don't have enough posts to post the full url - no vested interest in the company other than they are supplying the kit). Also search Polycore-Australia who is the Australian Distributor (or so I believe) of polycore. I hope Gunnadoo corrects me if I'm wrong but in the wider sense the term polypipe can be just about any "plastic" pipe - electrical / plumbing / irrigation. However, the term is usually used to refer to black "plastic" irrigation piping.



Look forward to being a useful contributor to this board - it has already armed me with a wealth of information as I set off on this building exercise.



David

Jim
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What core?

Post by Jim » Sun Jul 19, 2009 8:10 pm

Hi David, welcome to the forum. I read about the P40 a while ago in Multihull World and it seemed like a good thing. I will have to come around and have a sticky beak when you start. That Polycore must be lighter than Carbon Fiber for a boat that size to weigh 3.8T dry, if that is so it will be a rocket with that sail area.

Good on you.

Jim.

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