Balsa cored hulls - old boats

gstraub · #1 (**permalink**) 01-24-2003

I''ve been looking at boats of the ''79 to ''84 vintage. A couple that I am interested in have balsa cored hulls. I once had a boat with a balsa cored hull and no problems, but the boats I''m looking at are getting pretty old and I''m concerned about the longevity of the balsa/fiberglass bond, as well as the potential for a waterlogged or rotten core. Any thoughts on this issue, especially with regard to the age of the boats?

Gerhard

Jeff_H · #2 (**permalink**) 01-24-2003

There is no one single right answer here. In a boat that properly constructed, properly maintained, and has not had major trauma, there is nothing wrong with a balsa cored hull. Potentially they can have an equal or longer lifespan than a boat with a hull that does not have coring or adequate framing because fiberglass tends to fatigue if it is allowed to flex a lot.

BUT that means examining each boat on a boat for boat basis. The other problem has to do with the specific time frame that you are considering. This is the period that blister problems was at their worst. Blisters can greatly accelerate fatigue in non cored boats and delamination in cored boats by weakening the laminate and allowing moiture to migrate deeper. During this period I especially perfered boats that had substantial internal framing as it helps with both cored and non cored hulls. Internal framing reduces the stresses on and flexing within the skin and probably offers the most durable construction over the long haul.

(That is how my current boat which was built in 1983 is constructed and was one of the reasons that I bought the boat that I did).

Jeff

tsenator · #3 (**permalink**) 01-24-2003

Be vary wary.....20 year old boats have a long time for water ingress and on cored hulls the problems can be very damning. A solid hull is much less critical to water intrusion.

In any event I would get the *best* surveyor money could buy. One that has extensive experience with water intrusion into Hulls. Just any surveyor won''t do and it will be money well spent.

Jeff_H · #4 (**permalink**) 01-24-2003

"A solid hull is much less critical to water intrusion" but far more prone to fatigue problems.

Jeff

gstraub · #5 (**permalink**) 01-25-2003

Thanks for the detailed comments, Jeff and all. I was hoping you folks would make my decision easier!!

Gerhard

paulk · #6 (**permalink**) 01-26-2003

We are dealing with this issue right now, as a yard preps our 1981 boat for painting the topsides. They are claiming that high moisture content in the core, especially along the top edges, near the toerails, mostly midships, will affect the longevity (and appearance) of the awlgrip. We are having samples taken to determine how "wet" the core is in different places. Overall, the hull appears sound, though there are a few blisters under the waterline. The problem is that wet core often preceeds delamination and rot. It is sounding like we need to dry things out a bit -- difficult on a boat!

tsenator · #7 (**permalink**) 01-27-2003

Paul,

Where are you located? Do you haul your boat every winter or are you in warm water and just haul for maintenance? Have you owned this boat for the full 20 years?

sailingfool · #8 (**permalink**) 02-03-2003

I suggest you review the material about cored hulls on www.yachtsurvey.com. The author is pretty vociferous about this subject, but certainly backs his opinions with a lot of engineering data. Our decision was no cored hulls need apply.
Good luck.

Jeff_H · #9 (**permalink**) 02-03-2003

Actually, I find that there is a whole lot of hyperbole on that site that really is not borne out in the literature nor in my research with other experienced surveyors, yacht designers and marine engineers. Also much of the limited data that appears on that site seems to reflect practices really not used in sailboat construction.

Jeff

paulk · #10 (**permalink**) 02-03-2003

We bought our cored-hull knowing the potential for problems was there. The previous owners had raced her hard, moved fittings around without bedding them properly, hit things, had people hit them - the whole show. We fixed the cabintop, which had become a soggy mess of balsa, from the inside. Six seasons later, we still race her pretty hard (10knots with the chute up in 25 knots of breeze) and the yard has taken core samples that show one area of wet delamination that we think was caused because the previous owners screwed holes into the interior liner aft to secure wiring , and then added water by not packing the rudderpost stuffing box. The quarterberth plywood facings held the water over the screwholes, and voila! We expect to fix that this winter. Getting the deck to drain better in the way of the toerail should help dry out the topsides. With any luck (knock on wood!) we hope to have another 10 years with our 1981 baby.