Davit Fitment on Inflatable, Removal and Replacement
Al Zanni asked the following:
The davits on my inflatable dingy are peeling and separating from the bond. How do I remove, clean and reapply them?
This job is considered "above average difficulty" and is best sent out to an experienced professional. In addition, there is a good chance you will cause damage to the fabric which will require additional repair or patching prior to the re-installation of the davit fitments.
The way the pros do it, varies depending on whether the boat is PVC or Hypalon, but this is how they do it. First you need to remove the fitment.
For PVC: Use a heat gun, something more powerful than a hair dryer, and carefully heat the fitment, being extremely careful not to scorch the fitment or adjacent fabric. Now let the fitment cool down to ambient temperature. This is best done in the shade when the ambient temperature is coolest such as early morning. Repeat this process 7 or 8 times. This will cause the adhesive to crystallize and make it easier to separate. Now use a dull blade and carefully pull the fitment away, while working the blade between the fitment and fabric until you have it off.
This heating cooling degradation of adhesives explains why some inflatable boats experience seam delaminating. This is especially true of dark colored boats or boats that are stored in direct sunlight without a cover, such as upside down on the deck. Of course, there are other reasons for seam delaminating, such as using the wrong type of cleaner or solvent based protectants but that is beyond the scope of this discussion.
For Hypalon: Use a heat gun, as above, except carefully heat the fitment and tube at the interface while pulling the fitment away, using a dull blade to help with the separation. You will need enough heat to soften the glue but not so much that you will scorch the fabric or fitment.
The next step is to clean the tube and fitment and remove any remaining adhesive. This can be done using Toluene on Hypalon and MEK on PVC and scrubbing with a plastic kitchen scrubber.
If any of the coating is removed from the fabric and you get down to the cording, it will cause the boat to leak and this must be properly repaired. The way to do this is first build up the damaged fabric to the same height as the surrounding area with the special 2 part adhesive made for inflatables. Weaver makes an excellent 2 part adhesive which can be purchased at most Inflatable Dealerships. An 8 oz can is about $30 or $40. Do not apply thick coats, the thinner the better. Wait for each coat to dry before applying the next. This is a contact type of adhesive so work carefully with it and keep it clean and free of dust. This type of adhesive will discolor the adjacent fabric so apply it only where you need it.
Now you need to apply a patch to hide any repairs and discoloration. The patch should be made of the same material as the boat and if you can not match the exact color then use an attractive contrasting color so it looks intentional. Some repairers will cut the patch into an attractive deign or pattern and apply the same patch to both sides of the boat to disguise the patch. You need a minimum of 1" larger than the fitment and sharp corners should be avoided so radius the corners.
Apply multiple thin, thin, coats of adhesive to the patch and tube, letting each coat dry before applying the next. Carefully read and follow the adhesive manufacturer’s instructions. The placement of the adhesive must be exact as it is difficult to remove and will discolor the tube or patch. When the final coat is dry, carefully apply the patch to the tube, starting at one edge, while holding the remaining patch off the tube and carefully working it on with a plastic or wooden stick being careful not to get any wrinkles or trap any air bubbles. Remember this is contact cement. Once the two surfaces touch, they are stuck permanently and can not be easily removed so you only get one shot at this. If you get wrinkles or air bubbles or misalign the patch you will have to try to remove it as above, make any repairs and start again with a bigger patch.
The adhesive must be right to the edge but not past. If you don’t get it all the way to the edge, you will have delamination problems, if you get it over or on the face of the patch, you will have discoloration.
The patch needs to be held tightly to the tube for 48 to 72 hours. This can be done by strapping multiple pieces of 1"x1" wood, of the appropriate length sufficient to cover the patch, to the tube.
Once the patch has set, apply multiple very thin coats of adhesive to the fitment and the patch where it will go, allowing each coat to dry before applying the next and when the final coat is dry, carefully apply the fitment, being very careful to align it perfectly. Again, you only get one shot. Start at one edge and apply it, rubbing with a piece of wood or plastic to work it onto the patch without entrapping any air bubbles. Strap pieces of 1"x1" pieces of wood to the tube, to secure the fitment and allow it to cure for a minimum of 48 hours and 72 hours before hooking up the boat to the davits.
If you have the skill, time and patience, you can do it but it is tricky and you only get one chance. Remember the reason that the professionals are professional is that they have training from someone who had already screwed up their share of boats learning how to do it, have had lots of practice on someone else’s boats and have probably screwed up their share of boats learning how to do it as well. That’s why they get the big bucks.
Another word of caution; the adhesives and chemicals that you will be working with are toxic and flammable so protect yourself, read the instructions before starting and treat the chemicals with respect. Don’t get it on your skin. Don’t breath the fumes and make sure there are no open flames or anything that can spark, in the work area. No Smoking. Even the heat gun can ignite the fumes. Work carefully and safely.
Thanks for your question