One of the most common jobs would be mounting marine electronics. Almost all boats have a fish finder installed or will have one installed at some point in their service life. Fish finders or other electronics like a GPS will come with the standard instructions for mounting and it's up to the individual to take care of it. The directions will usually emphasize mounting in the correct location and insuring all electrical connections are sound. Remember, as with anything electronic a fish finder or GPS is can be sensitive to electrical noise and routing wires and such should take this into consideration.
Now the actual installation, you are given screws to mount with and maybe a template. You have your drill ready and well, you're still hesitate to drill. I can't say that I blame you just remember you have one shot at getting the location correct or you'll be left with blank holes.
Drilling fiberglass is not hard to do and good prep work will make a big difference. A few words of advice here always go slow. The fiberglass on a boat hull will have gel coat and you can damage the finish if you're not careful. Also, it sometimes helps to place a piece of masking tape over the area to be drilled. If the gel coat attempts to chip from the edge the tape will act as a good barrier providing a clean edge. Always try to drill into the gel coat first but if you have to you can drill from the fiberglass side just understand that a risk of chipping is increased by drilling that direction. If drilling from the back side, always tape the finish to protect it.
Now all the holes are drilled and you are ready to mount. You've talked to a few people on what sealant to use but still are not sure. Based on my own experience most will use 3M 5200 which would be a huge mistake. That product is designed for a below the waterline application and extremely difficult to remove meaning it is intended to be permanent. Keep in mind it has strong adhesive properties and you'd literally be gluing the bracket to your boat. If you attempted to remove, you could possibly remove the finish causing a bigger problem. A good alternative would be a bedding compound or another marine sealant. Never use straight silicone to avoid future problems. If you ever need to reseal or mount something else adhesion to existing silicone surfaces is virtually impossible. I also understand that most boat owners will change out electronics over time so it is advisable to using something serviceable. Never use household caulking or other products even though they are cheaper. They will not survive for very long and are not designed for marine use.
Now as you insert the screws coat the screws themselves and only apply a small spot of sealant over the hole. It will not seal any better by using large amounts and will not look good either. The fiberglass should be the only surface to seal here so if you did not chip the gel coat finish too much you should be good. Tighten only enough to serve the purpose and allow sufficient time for the sealant to dry before using.
The last item for a successful installation is the hardware. Don't cut corners here thinking you can purchase cheaper hardware for the job. All hardware must be a suitable grade to withstand the environment. It is natural for boats to get wet so if using anything which water will damage it will surely fail. Stainless steel will be the best choice while brass is also resistant but does not work as well. If necessary, purchase extra hardware to insure your installation is done well.
So now the job is completed and your new fish finder is installed correctly. All the holes are sealed and drilled as required and the hardware is sufficient for the installation. It doesn't seem so scary and now a little more peace of mind to help you along. You can do it!
I prefer to purchase all my Boat Parts and Outboard Parts on the internet.
