Captain's Choice Marine SurveyOrillia, Ontario |
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When I walk up to a vessel during an inspection and look on the platform and see dinghy holders installed in a rather haphazard fashion, I'm almost certain it's going to have problems. When an owner or his dock expert friend install dinghy holders, they usually mark off the holes, drill four different places per side, slip on the davit and bolt or screw in a stainless fastener or worse, standard zinc coated fasteners and call it a day. Then the owner can't figure out why he has damage to his platform a few years later. If you consider that the swim platform is close to the water and is immersed in water during a day of boating, it's easy to see why core materials get damaged if the fasteners and hardware aren't sealed off properly. Moisture is going to enter the core materials and eventually cause rot or de-lamination.
The manufacturers can be at fault as well when they install stanchion bases with through hull bolts that aren't sealed off after drilling. The majority of damage can be prevented if certain precautions are taken after drilling the holes. Some think that by using a sealant it will stop this problem but in fact unless the owner pays strict attention to the sealant condition, core damage can still develop if the sealant dries out and stops doing its job. Sealants like Sikaflex and 3M products work well but do not last forever. Repairs to swim platforms and decks can cost you thousands of dollars and installing hardware properly will save you lots of money. It is NEVER a good idea to drill holes into any exterior areas on a vessel, but if it's absolutely necessary, it should be done correctly. One way of getting this done properly may take a little more work but it will save you in the long run. When you want to drill holes for a dinghy system on your swim platform, you must first look under the platform to find out what you are drilling into. On some platforms, the builder will reinforce the trailing edge area with core materials much thicker than the balance of the platform. This is an indication that there maybe wood under the laminates or perhaps foam core, balsa core or other materials. Now figure out what size hole you must drill to fit the fastener, eg 5/16". Chose a drill several sizes bigger, eg.3/8" and drill the amount of holes required. Now what you want to do is take a piece of masking tape and place it over the hole underneath. Mix up a small batch of epoxy and fill all the holes up to the top of the platform. After full cure, carefully place the fixture over the area of epoxy and drill the appropriate size eg. 5/16". Now the core materials are not exposed to moisture. When installing your hardware make sure you use oversized washers or backing plates made of either stainless steel or aluminum that will give the area lots of support. Sealing the holes with a good quality of sealant will help again to prevent moisture from entering the laminates and core materials. It's imperative to seal, support and secure the hardware from moving or allowing moisture from entering the core materials. |
In my day to day job of inspecting vessels for surveys, the same problem seems to occur to a majority of boats. Namely, swim platform damage of some sort, usually de-lamination and wet core materials.
Similar problems result from someone installing an anchor windlass to the fore deck with very large bolts or the guy who installs fender brackets to the side decks and again wonders why the decks are de-laminated or soft after a few years.
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