Ladies / Gentlemen, I am writing to you because I read where you were a proponent of balsa cored laminate hull construction techniques and have employed balsa coring in the hull construction of some of your boats.
I am considering buying a used cruising sailboat to liveaboard. It is a Bruce Roberts designed 36, pilothouse / cutaway full keel ketch, constructed in 1981, and has a fiberglass hull cored with balsa.
It is not my first boat. I have previously owned a 34 foot skipjack ketch, and a 32 foot Al Mason designed steel sloop, which I lived aboard for two years.
I have searched around the Internet, fruitlessly, for articles or information about balsa cored hulls (except for the Baltek Corp. site–very informative about new technologies). Therefore, could you please direct me to sources for information on evaluating balsa core constructed hulls? Also, the boat is moored in the Ft. Pierce, Florida area. Could you recommend a competent marine surveyor in that area who could conduct a survey of the vessel for me? I am reluctant to just choose any accredited surveyor and not get someone who knows what to look for in evaluating balsa core composite hull construction.
I don’t want to buy a water logged boat. The Baltek site claims that end grain balsa has a closed cell structure and, therefore, very little permeability, even after being submerged for long periods, and covered by fiberglass gelcoat subject to seepage–based on a 14 year test they conducted.
I plan on having the boat hauled for inspection, as part of a pre purchase survey, but am reluctant to start drilling holes in someone else’s’ hull when I’m not even sure of what I would be looking for; spongy? A certain sound when banged against? Also, I am in Louisiana. Before going to the expense of going all the way to Florida, I’d like ask more informed questions of the owners, regarding construction details of the hull laminate process.
Any thoughts you might share with me on the subject would be appreciated. Thank you for your time and consideration. By the way, your boats, and the design logic underlying them, are brilliantly conceived. Sincerely, Ed
Hi Ed: We did our first boats with balsa core in the mid 60s–and have used it ever since, along with other materials when they were optimal for the job at hand. The major advantage of balsa is its resistance to damage. This comes from high core resistance to shear loads, and to excellent bonding properties.
However, like any building material, it has to be used correctly to be structurally sound. But if it is done right, it will last for a long time. Some of the early Deerfoot designs we built were cored–and all of these are still going strong 18 or more years later.
A good surveyor, is of course, a must. A lot can be learned by simply tapping on the hull and deck with a hammer. You will probably want to remove some through-hull fittings, deck fittings, and even possibly a chain plate or two to check for moisture (and the attendant rot).
It would not be unusual to find some areas where the core had separated from the skin, or there were soft/wet spots around fittings. This does not automatically disqualify the boat as in many cases these situations can be repaired. Of course you will want to negotiate who is going to pay for the repair!
As to suggesting a surveyor, we cannot help you there. We don’t know anyone in the business in your part of the world. However, any reputable surveyor will have a handle on the issues discussed above–they deal with it al the time. One word of caution on the choice of surveyor–often the broker involved will suggest a name. We feel this has an inherent conflict of interest. The broker usually wants the sale to go through, and the surveyor often wants more referrals from the broker. So, it is usually best to do some sleuthing and find an independent surveyor.
In our book, Offshore Cruising Encyclopedia you’ll find a large section on construction materials in general and balsa core in particular. Good Luck- Steve Dashew
Posted by Steve Dashew (November 30, 1999)
