Balsa core vs. foam core

[buckknekkid]

[quote=FAST FRED] Same as with Tiawan Tubs when the GRP paint is puncured and not resealed. WOOD ROTS. we are waist deep into the cockpit refit right now, trust me it ROTS!

[Alan M.]

No denying that wood, as an organic material will rot in cases of neglect. I would suggest that as a core material it would take more than just scratching the paint off it to allow water to enter though. Also, most end-grain balsa used for coring has a coating of epoxy on it, and is made of relatively small "cells" glued together, which dramatically restrict the movement of water, which being across the grain, is very slow to start with. As for having to routinely remove and re-seal deck fittings, it's a better practise to remove the core from the deck and replace it with solid glass/epoxy, where ever you attach deck hardware, regardless of what the core material is.

[buckknekkid]

I believe the reference was directed to Taiwanese boats, of which some I have painted were nothing but foam and paint.

[Julian Carrick]

Lantor Coremat is better than Sphericore and Upica as it is made using short fibres and therefore breaks down quicker and releases the air better. If you are doing compound curves XM is even better as it drapes in all directions without creasing, takes 10% less resin and has good pick up strength when wet out on the bench.XM is also getting a good reputation as a print through blocker if you have a lot of heavy wovens in the hull

[buckknekkid]

hope this works

[Alan M.]

Yep, it works. Shows end grain Balsa to be an excellent core material too, doesnt it?

[zerogara]

I believe that where balsa suffers most in comparison is where a localized impact is severe enough to cause damage to the core and delamination. All types of foam will stay in tact in the surrounding areas where balsa will delaminate in a much wider area.
Thanks to buckknekkid for the chart, one with some equal layers of frp would be a good comparison as well.
Spheretex sphere.core SBC has a comparative analysis of 4 composites where they show how they are on par with balsa but have better bonding qualities than balsa as the problem with bonding dissimilar materials is their advantage.

http://www.spheretex.com/pdf/Sphere.coreSBC.en.pdf

[Raggi_Thor]

I just received a free package of samples from spheretex and will compare with divinycell. Have you did some testing?

[waikikin]

I had A 10 metre sail cat that used 6mm coremat in the round bilge sections of the hull & topside panels[she had a spray deflecting chine & 1 other clinker style chine in the topsides- these seemed to help stringer the topsides & formed landings for bench & bunk heights], the decks were foam cored.During seven years of ownership, 2 of which in daily use, dingy knocks ,wharves etc left nothing but light gelcoat scratching.Also sailed well, at 2.7 tonne not outrageously heavy for a 10m cat with bridgdeck cabin. She was molded by Endeavour Yachts for Beach Marine[both gone] & appeared to have been designed for this style of construction & IMO a terriffic advert for success of it.Jeff.