From time to time there are comments on CSR about coring. Many people consider cored hull boats to be evil and won’t even consider owning one. The truth of the matter is that cored construction is quite common and is used on many high line and expensive brands.

If you have read many threads on boat buying, you almost always see the recommendation to survey prospective boats and have that survey done by a competent marine surveyor. I was the Sea Ray dealer (where we also happen to keep our boat) the last couple of weeks, and saw the first cored hull problem this dealer has had to deal with. I thought some of you might like to see the problem and how the dealer and Sea Ray handled it.

The boat involved is a 2000 460DA. The owner noticed the boat listing in the slip. At first, several months ago, it was a little bit, barely noticeable from the stern. Then it got worse. Eventually the generator exhaust was almost submerged which on this boat means she was listing about 3” to the port side. The dealer found the port side hull vent had been leaking. The vent hole is sawed into the cored side, so any leak can let water get into the cored area between the inner skin and the outer gelcoated skin. This particular boat had been leaking a while, and the hull side coring was found to be wet from the stern to about 5’ forward of the hull vent…….a total of about 10’ worth of wet hull/coring. The fiberglass guy at the marina identified the wet area by sounding the hull and with a moisture meter.

This is a photo of the water draining out of the core:

The hull vents were removed from the hull and about 3/16” holes were drilled in the bottom of the cored area to allow it to drain naturally. The bow was raised slightly until no more water would gravity drain out of the lowest, aft-most hole.

Next, shop vacs were taped to the hull and any remaining water was vacuumed out of the cored side.

Even though a large area of the core got wet, the extent of the damage in this case was some rotten coring between the inner and outer skins around the hole sawed in the hull for the vent. The damaged area needing repair was limited to the area on the bottom and aft end of the vent which was about 1” to1-1/4” into the core from the opening. The rotten area was dug out and removed, as shown here:

The repair was done by digging out the rotten balsa and filling the area between the skins with West Systems Epoxy thickened with #403 Microfibers. The holes drilled in the hull were filled and sanded smooth. Since the repaired area at the vent was covered by the vent panel itself and the holes drilled in the hull were below the waterline and in an area covered with bottom paint, gelcoat repairs were not necessary.

While the usual feeling here on CSR is that wet coring is the kiss of death, this is a case where a bad situation was caught and properly repaired with no long term negative impact on the boat or its value. Since the rotten balsa was limited to a relatively small area, and the wet area was easily drained and dried out, the boat was only out of service about 10 days and the cost of the repair was very low. In fact, the owner wanted the boot stripe replaced while the boat was out of the water and it took longer to get the stripe from Sea Ray than it did to fix the wet coring.

If you have read much of what I post about establishing and maintaining positive dealer relationships, here is a good example of why: This boat is kept at the dealer’s marina, it is well maintained and most of the maintenance is done by the dealership, so the dealer knows the boat’s history. The Service Manager was able to get Sea Ray to handle the repairs for the owner and an accommodation even though the hull is a 2000 model…….4 years out of the hull warranty.

Summary:
—> A wet core isn’t a good thing, but does not necessarily mean the boat is DOA.
—> A wet core can be repaired reasonable quickly and easily without breaking the bank. This example was less than $2000.
—> A core with significant wood rot is a different story since the rotten core must be removed and replaced.
—> Any part or item mounted in a sawn in hole in a cored structure is a potential source of water intrusion into the coring. Consider having any such items like hull side vents, windlass foot switches, spotlights, etc. removed and the coring sealed with epoxy or resin then re-bed and remount the removed part.
—> The cause of the problem pictured here was not the fact that the manufacturer chose to use cored construction; the coring was properly done and without defect. In this case, there was a bad seal around the side vent.
—> Were this a boat being purchased without a survey or the wet area not found by a surveyor, the entire cored side could have rotted which would have made the term “major repair” an understatement.
—> A wet core doesn’t usually just happen with no notice. An observant owner who knows his boat will usually see signs that something isn’t right… Look for listing, unexplained sluggishness or bad performance, staining, mold/mildew, drips, leaks, water/moisture where there should not be any.