Balsa and Corecell，what is the difference？

Here in Canada Corecell 12mm is $50 m2 balsa 12mm is $40

 

By the look of where he is its Xiamen , China and chinese love balsa .

i was given a copy and paste schedual from the designer for the big boat we are doing !!,That had quoted 19 mm Balsa for the topsides , my reckoning was almost twice that thickness of foam and a few more layers of glass . So we came to a compremise of 25 mm .
Using 19 mm is ridiculas for a 90 foot boat and a sprinkling of glass each side !!
Oh sure has stiffeners along the side but even they are questionable how they are made .
Have already shifted there location to parts that will give more and much better support !!,when its all combined with other structual frames etc etc get fitted in place .
Its a prefect example of not standing back and looking at the over all construction details of where things fall and utilising overlaps of materials and its extra stiffness and strength gained to there fullest advantage .

 

I got balsa & Klegecel, already paid for. I chose balsa for hulls because it takes the small everyday bumps without bruising-obviously performing differently with a "bigger" collision, & foam for decks 'cos "one day" some dh is gunna install stuff without the proper close outs & annulus & I don't want the consequences to balsa with that- with hulls there's few "holes" to deal with. With the design study & testing there was a slight weight penalty to balsa but only a couple of cases overall as foam would be about 20-25% thicker & would have required a thicker/heavier glass laminate. The cost saving was significant, probably not so much as a percentage of a finished boat but for myself means I can eventually get what I wouldn't otherwise be able to afford sooner. Just for interest on a 12.4m cat, balsa to hulls is 19mm & 25mm for Fwd 1/3, underwing & deckhouse roof is 40mm foam, there is extensive use of 20mm & 15mm plain & contour foam in bulkheads, furniture & champer panels to tunnel.
So there is more to it than price alone but it is still an important part of the equation. All the best from Jeff.

 

Everything comes down on price. It is just a matter of looking at the price of materials alone, or the price of the whole structure, possibly even after X years of service.

An example is composite bridges. More expensive than steel bridges, looking at the bridge alone.
However as the composite bridge is much lighter, the foundations can be lighter and more simple (cost saving at 0 years of service).
Maintenance is limited to cleaning every now and then, no paintwork needed. and the structure is without nooks and crannies, so easy to clean. Only after 50 years a new layer of gelcoat needs to be applied, after which the bridge can be used for another 50 years. Huge savings after 50 and 100 years.

Whether to go for balsa, pvc or san foam is a matter of calculation, taking into account the availability, habits of the yard, and of course technical demands.

Larger boats are all calculated for strength and stiffness, sometimes according to classification rules (Lloyds, DNV, ABS, GL) and builders and/or material suppliers should be joining the project early to ensure that materials are specified which are obtainable within budget and time schedule, and that not only strength requirements are met but also that the structure can be built easily and within budget, and that cosmetically the thing looks OK. (which might need some extra material every now and then)

Just jumping in and specify thicker or thinner laminates based on experience does not always work, and should always be communicated in the complete project team.

 

no perfect materials only perfect for you

where are you buying your core cell?...only place i know is Noahs in T.O.

core cell is (using north american dimensions) an 18mm 4 x 8 sheet or about 1214 mm x 2438mm is 188.00 at noahs IF you buy more than 15 sheets. reg- 214.00 cdn a single sheet- 32 sq ft.

I personally like core cell much better since you can use polyester resin - balsa costs almost as much but you cannot use polyester---(if your cheap like me)

trade-offs

core cell- more expensive
more easily holed
lighter
less resin consumption
can use less expensive poly resins
will not rot or is not friable
easily formed to compound curves
light weight to work with
balsa- less expensive but price difference is marginal.
- very strong and stiff-
-hard to puncture
(i tried to puncture some 18 mm in my now infamous hammer tests- it only dented the wood even without a skin-where plywood would have easily been holed...very very tough stuff!)
-heavier
-must use epoxy
-cannot form to compound curvature easily, or if at all.
-has been known to withstand hurricane bashings where other cores failed.

the bottom line is preference-in the end most hulls-whether steel -cored -wooden-ferro-or other types all end up being pretty darn close in costs, each has advantages and disdvantages-each has trade-offs- there is no "perfect material" or we would all build out of one perfect one...
there are only - "preferential" materials--the choice is yours...​

 

yes noas,only place i no of.wish there was somewhere cheaper.i guess i could order 15 sheets but how do you hide that from the wife?

 

what ????????

balsa costs almost as much but you cannot use polyester ????? what ??????

If you are from a differant planet
You can use polyester !! you can use Vinylester with Balsa . Its been going on since before you were born !!! Its been going on before foams were even thought of !!
So the 90 foot boat we are part way through is all polyester and balsa top sides its wrong ?? what about the boat build in 1972 that are still in use to this very day all polyester and balsa and never had any kind of problems .
I think you better re read what ever book you got that information from just to make sure !!

 

True - Polyester is the norm for Balsa, even the netting holding it together is engineered for dissolving in Polyester, and needs to be pulled off for Epoxy.

The bond on core materials is not huge, and doesn't need to be, as core is only a compression member.

 

sure you can use poly-- but then again you can use poly on ply too--its also the norm--or was till every poly boat ive seen rots or delaminates...with wood--id never use any poly resin...but hey-whatever floats your boat!

 

the core has to withstand a lot more forces than just compression--i.e. shear-impact-torsional-and tensile forces just to name a few...poly sucks for wood-- wont stick...

i do admit --i personally-have never built in balsa core-but ive built in ply and poly and would never do that again... i like core cell for poly though and i DO have experience working with it--its amazing stuff...

 

Polyester not sticking well to timber is not the same as end-grain balsa, if it wasn't end-grain might be a different story.

 

i guess then a formal "recant" of my "must use" epoxy statment might be in order--I stand corrected..thanks gents!

 

im talking polyester !!

End grained Balsa soaks resin quiet quickly and a 30 minute gel time you could exspect it to penetrate a good 3 to 5 mm down into the grain !! .
its best to seal the balsa before you glass for the very reason that it will suck the resin out of the laminate you lay over the top . .
Years ago we used a special semi flexable resin to seal the balsa , the same resin we used to make fillers and never had it crack at all !! combined with micro fibres was vertually indistructable .
Just like i said back aways i never seen a laminate ever come off balsa it bonds so good , seen the glass tear to shreads but never part at the interface between the two !!.
And the scrim is glass these days and dosent dissolve no mater what resin you use so dont need to peel it off !!.

I did a little testing of my own last week with a big hand full of 25mm balsa blocks .
Water will go completely through in 20 to 30 seconds .
i used uncatalysed resin and in 10 hours the resin has started to appear on the top surface of the blocks!! 25 mm !!.
The manufactures here in china are more selective and the hardeness is much more consistant than it ever was before . The older balsa was crazy with really hard grains and really soft grain and everything in between all mixed up and against each other . trying to cut with a knife was hard work, band saw is much easyer and makes a far better job . We pre make all the semi rounded bevelled edging and lay it all at the same time !saves time looks great and easy to do vertually no filling any where if you take your time and think a little also vertually no waste as just about everything can be used up !!!.

 

Airex has a nice movie on a CET scan of balsa, impregnated with resin. They have a rotating view, where the balsa is removed from the view, so you can see the penetration, and even can calculate the resin volume. Pretty impressive.

This was shown to me at JEC 2012, where Airex introduced their "limited resin system" on their PET cores (modified surface to limit the amount of resin needed) and balsa (surface impregnated also to limit the amount of resin used). The results were pretty impressive. They might have it on their website now.

 

Just spent 30 minutes searching and not a thing anywhere that i could find !! !!!