All 355/356 Owners Must Read - Rear Deck Core Failures
Posted: June 27th, 2023, 7:56 pm
Hello All,
Three seasons ago I purchased a 2001 356 aft cabin which I absolutely love. I got an incredible deal on this gorgeous boat because of a soft spot in the rear swim deck which is not a quick and easy problem to rectify. I learned that this was a VERY COMMON problem with this model of boat and was told the failure was caused by the installation of a grab handle installed in the rear deck on most of these boats to compensate for the AWFUL factory swim ladder which makes in nearly impossible to get back onboard from the water without it.
I tackled this gigantic project this spring and have to share the shocking thing I found in the process. My failure was not caused by the poorly installed grab handle in the platform BUT WAS CAUSED BY A HUUUUUUUGE MANUFACTURING DEFECT RELATED TO THE ATTACHMENT OF THE OPTIONAL FACTORY DECK STORAGE BOX THAT PRETTY MUCH GUARANTEED THAT THIS PLATFORM WOULD FAIL. I am writing this post because I am not sure how many 355s & 356s with storage boxes have this defect, but any boats that were built like mine WILL HAVE A PROBLEM (weather you realize it yet or not).
Here's the story:
I mapped out the part of the deck that I believed had failed by using a hammer and listening for the areas were there was a solid thud, compared to a hollow bounce. I believed that the rotted portion of the deck was as follows:
Although my map of the rotted core was pretty accurate, I learned after I started cutting into the deck that the balsa was very wet extending far past the places where the balsa was completely rotted.
I ended up removing pretty much the entire swim platform because even though the balsa that was still structurally sound was completely saturated with water. This is were things got interesting and I discovered what the real failure was caused by. Amongst the balsa core, there are sections of marine plywood in the shape of the storage box, to give a more substantial material for the deck box screws to "bite" into. If you look at the photo below, I have marked the approximate locations of the screws holding the storage box to the swim platform. The circles in green are locations where the screws come through the outer skin and into the marine plywood. The circles in red are locations where the mounting screws "missed" the plywood frame and went directly into the balsa core.
THE FRAME THAT WAS MEANT TO PROVIDE A DENSE MEDIUM FOR THE SCREWS TO ATTACH TO WAS MADE TOO BIG AND MOST OF THE SCREWS MISSED IT!!!!!!! Carver simply put some butyl sealant on the screws and sank them through the skin thinking that they were biting hard into the marine plywood....but most of them were not. Over the years of boat flexing (from use and storage on land) caused these screws to turn into a "file" which made the holes through the deck quite large. I was actually able to pull 3 of these screws straight out of the platform without tools! With the way the rain flowed on the back of this boat, it streamed around the port side of the box and under the left forward and bottom areas where these enlarged holes existed.
I ended up rebuilding and replacing the entire swim deck balsa and marine plywood sections, I made the plywood underlayment in the correct size/shape so that all the screws went into the plywood. As an added measure of protection, I drilled a 1" round hole in all the mounting locations and filled them with Resin to that even future leaks through the holes have no path to the wooden portions of the platform.
I deleted the plastic grab handle and replaced the terrible swim ladder with an awesome unit with retractable handles made by an Italian company called Nautix.
Then got it all re-glassed and gelcoated back up where it was almost ready to hit the water again:
After re-installing deck box, finishing touches, and installing Seadek flooring to provide a non-skid surface for the platform, I am fairly happy with the way this all turned out....even though it was WAAAAAAY more work than I anticipated.
So, I wanted to share this for anyone who might have one of these boats. Not sure if they ever offered a larger box, but the frame under the outer skin is simply too large to do what it was intended to do...which was to provide a solid material to accept screws though the skin. Total fail here. Also remember that even if your swim deck might appear to be solid, it could be completely soaked and has just not rotted yet. I would recommend anyone with one of these boats and a deck box check their platform with a moisture meter to see if your boat is slowly getting really sick. Dealing with this problem sooner rather than later could save you lots of headache and $$$.
Three seasons ago I purchased a 2001 356 aft cabin which I absolutely love. I got an incredible deal on this gorgeous boat because of a soft spot in the rear swim deck which is not a quick and easy problem to rectify. I learned that this was a VERY COMMON problem with this model of boat and was told the failure was caused by the installation of a grab handle installed in the rear deck on most of these boats to compensate for the AWFUL factory swim ladder which makes in nearly impossible to get back onboard from the water without it.
I tackled this gigantic project this spring and have to share the shocking thing I found in the process. My failure was not caused by the poorly installed grab handle in the platform BUT WAS CAUSED BY A HUUUUUUUGE MANUFACTURING DEFECT RELATED TO THE ATTACHMENT OF THE OPTIONAL FACTORY DECK STORAGE BOX THAT PRETTY MUCH GUARANTEED THAT THIS PLATFORM WOULD FAIL. I am writing this post because I am not sure how many 355s & 356s with storage boxes have this defect, but any boats that were built like mine WILL HAVE A PROBLEM (weather you realize it yet or not).
Here's the story:
I mapped out the part of the deck that I believed had failed by using a hammer and listening for the areas were there was a solid thud, compared to a hollow bounce. I believed that the rotted portion of the deck was as follows:
Although my map of the rotted core was pretty accurate, I learned after I started cutting into the deck that the balsa was very wet extending far past the places where the balsa was completely rotted.
I ended up removing pretty much the entire swim platform because even though the balsa that was still structurally sound was completely saturated with water. This is were things got interesting and I discovered what the real failure was caused by. Amongst the balsa core, there are sections of marine plywood in the shape of the storage box, to give a more substantial material for the deck box screws to "bite" into. If you look at the photo below, I have marked the approximate locations of the screws holding the storage box to the swim platform. The circles in green are locations where the screws come through the outer skin and into the marine plywood. The circles in red are locations where the mounting screws "missed" the plywood frame and went directly into the balsa core.
THE FRAME THAT WAS MEANT TO PROVIDE A DENSE MEDIUM FOR THE SCREWS TO ATTACH TO WAS MADE TOO BIG AND MOST OF THE SCREWS MISSED IT!!!!!!! Carver simply put some butyl sealant on the screws and sank them through the skin thinking that they were biting hard into the marine plywood....but most of them were not. Over the years of boat flexing (from use and storage on land) caused these screws to turn into a "file" which made the holes through the deck quite large. I was actually able to pull 3 of these screws straight out of the platform without tools! With the way the rain flowed on the back of this boat, it streamed around the port side of the box and under the left forward and bottom areas where these enlarged holes existed.
I ended up rebuilding and replacing the entire swim deck balsa and marine plywood sections, I made the plywood underlayment in the correct size/shape so that all the screws went into the plywood. As an added measure of protection, I drilled a 1" round hole in all the mounting locations and filled them with Resin to that even future leaks through the holes have no path to the wooden portions of the platform.
I deleted the plastic grab handle and replaced the terrible swim ladder with an awesome unit with retractable handles made by an Italian company called Nautix.
Then got it all re-glassed and gelcoated back up where it was almost ready to hit the water again:
After re-installing deck box, finishing touches, and installing Seadek flooring to provide a non-skid surface for the platform, I am fairly happy with the way this all turned out....even though it was WAAAAAAY more work than I anticipated.
So, I wanted to share this for anyone who might have one of these boats. Not sure if they ever offered a larger box, but the frame under the outer skin is simply too large to do what it was intended to do...which was to provide a solid material to accept screws though the skin. Total fail here. Also remember that even if your swim deck might appear to be solid, it could be completely soaked and has just not rotted yet. I would recommend anyone with one of these boats and a deck box check their platform with a moisture meter to see if your boat is slowly getting really sick. Dealing with this problem sooner rather than later could save you lots of headache and $$$.
