TOPIC: Sandwich construction in small boats ?

I was recalling a boat a friend owned back in the 1960s. It was a Vega brand, about 21 or 22 feet long. The hull was a sandwich construction, with balsa wood squares between two layers of fiberglass, and it resulted in a very rigid hull. This particular boat was powered by an early Volvo outdrive, with a Volvo 4 cyl. engine. I know quite a few boats in the 23 feet and longer class have used sandwich construction of one type or another. Were there any boats in the 14 to 20 foot class that used such a construction ?

My Winner Scorpian has something inside the fiberglass hull. I think its wood. It seems very ridgid. It's a 15 footer.

That type of construction is called a "cored hull" They made cored hull boats in all sorts of sizes & shapes. They tend to rot, because water gets down in the core & there is no way to get it out.

I suppose rot might eventually become a problem for wood cores, although I'm pleased to hear that Winner is still sound. I know there have been other materials used to make cored hulls besides wood, including resin impregnated honeycomb paper and foams. I saw an article a couple of years ago , written, as I recall, by a marine architect or surveyor, about the damage done to some larger fiberglass boats ( 30 feet and up) by a storm. Some of the damaged boats had rather strange cores, such as crumbling plaster-like materials. The message of the author's rather terse comments was that the quality of many larger modern fiberglass boats had taken a nosedive, in order to save money. The result was excessive damage under conditions that a well constructed boat would have survived.

The 14' alumacraft alpex im restoring used the balsa core sandwich contruction. Im in the process of putting the new balsa core back in. I only got half of it in and im really suprised how rigid the hull is getting. Should be really strong

I had a sail boat the had a balsa core deck. If you ever drilled it you had to make sure that mo water got in what so ever.

After a friend had the deck on his come apart and what he had to pay to get fixed I sold mine and bought an older boat "1980 Newport 30"...Later I sold it to Ike, for it was kept in Galveston

Will never own a boat that will not fit on a trailer again

Allan

My 59 and 60 Crestliner Arabians are both origonally balsa core. The 59 core was water logged and the 60 is still water tight.

I removed all, including transom and used 1/4 ply sandwitched between glass and epoxy, 2 layers on the bottom. I had to shape the ply and curve it to fit the hull. It's very strong as was the origonal.

Key is to keep water out.

Switzer, post bankruptcy (about 1960 or 61) Shell Lake and Lund glass boats made in Shell Lake. Later Lunds maybe, I don't know.

Saw this stuff on a promo from Jamestown Distributors. ANybody used it yet? www.jamestowndistributors.com/userportal/document.do?docId=218&title=Core+Damage+Repair+-+Smith+%26+Co.+CPES

Balsa core was fairly common,made a very light,stiff hull with a minimum of stringers/frames needed particularly on smaller boats. It is very problematic on older boats as it is almost certainly had water intrusion with ensuing rot, that process has had 50 years or so to proceed since built. I have done core replacements, it's not bad EXCEPT removal can be difficult. The more rotted the easier!!! I just did a 74 Hydrostream Vector with jsut the bottom most rotted but removed it all anyways to insure integrity, the non rotted part was a bear. I did figure out an easy way by cutting scribes about half way in to he core with a circular saw in a 2 inch by 2 inch square pattern and then side cutting thses squares off with a long Sawzall blade on edge running along the bottom layer of glass. I then ground out the remaing random balsa remains with a disk grinder. Wear Tyvek jump suit, goggles and a good OSHA breather mask, gloves hat. Lots of dust, I got it all done in two days to minimize having ot put on the outfit.
Workmanship is almost always the big failure mechanism for water infiltration and wicking into the core on the older boats. They jsut were not built to stand up to the test of time.

Hello:
Did you use 1/4" ply on the deck too?
Thanks,

Juan E.