Balsa VS foam core

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groper
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Re: Balsa VS foam core

Post by groper » Thu Mar 07, 2013 6:42 pm

Sure, any shrewd person would have the engineering checked as you originally said. All im saying is, for the most part the laminates will be the same in either foam or balsa on a typical cruising cat. Its the laminates that are dictating the panel strength in the general application of what we are discussing, not the core. The thousands of foam cored catamarans on the water are testament to this fact.

At the end of the day, the weight difference is bugger all also. As most foam cored designs will have a heavier laminate shedule to account for the localized load problems i spoke of earlier. This wipes out most of the weight advantage the foam has over the balsa.

Like i said before, the cost function vs acheivable panel strength is what is driving the duflex balsa cored kit boat market. Foam with a heavier laminate, is a more expensive way of achieving the same end result as the balsa core / lighter laminate. The only penalty i can see, is the potential for water ingress - which is totally dependent on the builders skill level and attention to detail.

44c
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Location: Hervey Bay, Qld

Re: Balsa VS foam core

Post by 44c » Fri Mar 08, 2013 7:38 am

sea_bee wrote:I would assume that any 10 year old cored hull weighs more than it did when it was launched.

Back in the 1970's, ferro-cement was the wonder material for boat building. I can see the day coming when cored hulls (of any kind) will have a reputation similar to that of ferro-cement today.
I don't think so. In fact you really can't build a good performing multihull without using some kind of core - either balsa, foam, plywood or timber (cedar etc)

Ferrocement was seen as a cheap, easy and fast construction alternative.

Cored construction using multi-axial unidirectional glass laminates isn't cheap compared to spraying chopped strand glass. But it does produce very strong and light structures.

Most insurance companies won't touch a ferro boat. I can't see that happening with cored construction boats, there are simply too many of them.

Redreuben
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Location: Fremantle W.A.

Re: Balsa VS foam core

Post by Redreuben » Tue Dec 17, 2013 1:22 pm

groper wrote:Sure, any shrewd person would have the engineering checked as you originally said. All im saying is, for the most part the laminates will be the same in either foam or balsa on a typical cruising cat. Its the laminates that are dictating the panel strength in the general application of what we are discussing, not the core. The thousands of foam cored catamarans on the water are testament to this fact.

At the end of the day, the weight difference is bugger all also. As most foam cored designs will have a heavier laminate shedule to account for the localized load problems i spoke of earlier. This wipes out most of the weight advantage the foam has over the balsa.

Like i said before, the cost function vs acheivable panel strength is what is driving the duflex balsa cored kit boat market. Foam with a heavier laminate, is a more expensive way of achieving the same end result as the balsa core / lighter laminate. The only penalty i can see, is the potential for water ingress - which is totally dependent on the builders skill level and attention to detail.
It's more than dependent on the builder, also the sailor who grounds it, or the next owner who removes things, drills holes and moves things around.
Foam is more tolerant of neglect in that it is more resistant to ingress, don't believe the closed cell thing though, it will take up water if left long enough but balsa is a sponge and a sponge which rots. Not a fan. Have repaired too many.

mahnamahna
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Location: Gosford NSW

Re: Balsa VS foam core

Post by mahnamahna » Tue Dec 17, 2013 6:26 pm

Isnt this balsa vs foam debate getting a little tired now?

All the leading Australian kit suppliers offer balsa and foam options of most designs and balsa outsells foam by a factor of about 10:1 probably greater, that was a guess based on the blogs I follow.

It may well be that there are more repairs of balsa cored boats simply by dint of the fact there are more of them around. Maybe not, a lot of the production manufacturers use foam in molds because it infuses easier than balsa (grids cut in foam), but then they also use ester rather than epoxy......are you equally considering using vinylester or polyester because there are more of them around?

I know this posts sounds terribly argumentative by design, what is the value of this argument, it is akin to ford vs holden. There is no right or wrong.

So in the end who cares, make your choice, the choice is yours and is fair enough which ever way you go, both have their advantages and disadvantages and care should be taken whatever choice you make, whether you are the builder or 10th owner.

If repairing a balsa boat (and the repair of balsa or foam is equally difficult or easy depending on the situation and your skill, bothers you, choose foam. If repairing a boat bothers you regardless of material, dont build a boat, just sayin.

I am happy with my balsa build, and am sure I will be equally happy with it when I part with her. I am sick to death of over drilling and de-coring and back filling, but I would have to do that with foam, so dont see the difference.

groper
Posts: 239
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Location: cairns

Re: Balsa VS foam core

Post by groper » Tue Dec 17, 2013 9:45 pm

I think we are all in unanimous agreement here, for the most part...

At some point in the boats life, it will end up with a leak somewhere, somehow, someplace...every boat does.

Simple fact you can't argue with is that foam can't rot, balsa can...

I'm happy to enter into another discussion regarding costs and building boats which was an extension of my earlier post.

We build our own boats because we don't want to spend that much on simply buying a new one. Second hand market may not offer what we are looking for either. So cost of building is way up on the list for anyone I've ever met who is building they're own boat, if it wasn't we would just go and buy it and skip the 5000hrs of hard labour, and enjoy sailing right now... This is why balsa kits outsell foam 10:1 as you say, No other reason I can possibly think of. Designers also know the economics of the market they sell into, obviously.

When I priced up duflex from ATL for my build, std panels were $350 in balsa. The equivalent in foam were $500ea. So I chose to make my own panels as I thought the foam panels from duflex, were a bit too expensive to justify. Balsa panels were affordable, but I couldn't stomach the idea of a boat made from it back then. I've since changed my standing of this somewhat, next time I would use balsa duflex for a lot more of the boat, but still use home made foam panels aswell anywhere thee is a chance of moisture entering.

Redreuben
Posts: 27
Joined: Sun Dec 18, 2011 11:19 am
Location: Fremantle W.A.

Re: Balsa VS foam core

Post by Redreuben » Wed Dec 18, 2013 10:20 am

Exactly groper, I agree, the main reason is cost and I think that is a mistake on the part of new builders, furniture and everything else can be retrofitted later, hulls, decks and structural bulkheads cannot be.
And for that portion of the boat as a percentage of the total cost of the finished vessel it is a false economy, just my opinion.
If I was building today it would be foam hulls with a polycore fit out, Basalt fabric skins and eglass everywhere else, minimum vinyl ester resin but probably epoxy.

That being said If you have built in balsa and done it correctly, have total confidence in your boat. But don't take shortcuts when installing fittings and when using it repair damage that exposes the core pronto !

For those querying my bonafides I was an industrial laminator for about 15yrs, polyester mostly but helped pioneer vinyl ester use in spas and pools, built fibreglass boats and tooling, yachts mostly for a decade (employee) in polyester, vinyl ester and epoxy, and also spent about 7yrs in the repair/refit scene, power, yacht and commercial craft.

Whimsical
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Location: Fremantle W.A.

Re: Balsa VS foam core

Post by Whimsical » Wed Dec 18, 2013 12:12 pm

foam seems to be held in high regard because it won't rot but the other factors seem to always be ignored. Statements like water ingress are not a problem, from things i have read water ingress in foam can be a huge problem but not from rot but from delam. I have tried pulling skins off several types of foam and it is a whole lot easier than pulling it off balsa so i can see how the reports of hydraulic delamination in underwater areas are quite feasible.
One site from a surveyor showed huge delam and black water from a foam hul. The black was presumably the foam being broken down in some way.

I realy think that in the long term both will be rendered useless unless water is kept out. That is why i like the sheets of Duflex as each small block of balsa is isolated from the next preventing water from spreading. If hydraulic delam can strip the skin then the entire hull becomes a repair, the better adhesion to the dry balsa would in my opinion prevent the small area of wet balsa spreading.

We pays our money we take our chances, only time will tell

Jim
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Location: Cairns

Re: Balsa VS foam core

Post by Jim » Wed Dec 18, 2013 10:16 pm

I go with the Ford Holden bit of the debate. If you are going to lay awake at night worrying about water rotting your boat then perhaps we should all build in aluminium. If it's built properly then water won't get in.
Jim.

44c
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Location: Hervey Bay, Qld

Re: Balsa VS foam core

Post by 44c » Thu Dec 19, 2013 7:22 am

Then you lay awake worrying about electrolysis....

Trev
Posts: 160
Joined: Thu Jan 15, 2009 2:56 am
Location: Moruya NSW

Re: Balsa VS foam core

Post by Trev » Thu Dec 19, 2013 9:17 am


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