Balsa wood is a common construction material used in the manufacturing of fiberglass boats.  Used as a core material, balsa wood is placed between two layers of fiberglass to add strength and rigidity to structures that require it, usually the deck, many times the hull, and sometimes the other areas that require strength.

Using this wood in a marine environment where the boats are constantly exposed to water is dangerous because of the ability for the balsa wood to rot.  Once water enters the cored areas of boats using balsa wood, it is a complicated repair job.  The balsa wood is between two layers of fiberglass, and to remove and replace it requires removing a layer of fiberglass.  This usually involves grinding and sawing as seen here:


As you can see, there is a lot of dust created from removing the fiberglass to get to the rotten balsa. The balsa must then be replaced before the removed fiberglass layer is restored. Care must be taken to ensure that this is completed correctly in order to maintain structural integrity of the area that is being repaired.

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To prevent balsa rot in the first place, care must be taken when doing activities that have the potential to expose it to water. Adding fittings and features to structures that contain balsa wood require careful craftsmanship to prevent water infiltration.

Installing fixtures and fittings through balsa wood is possible, but careful work upfront will be very valuable in the long run. There are several ways to do this, one of them is here:


This method of making holes through your balsa wood-cored structure will provide a wall of epoxy resin around the hole and keep the balsa wood back away from any water that may pass through the hole. Good marine-grade sealants applied to the hardware will add another layer of protection.
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