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Choosing the Right Sealant or Caulking

When installing a new port light, re-sealing deck fittings or plugging a hole, the most important thing to keep in mind is using the correct caulking or sealant. A good marine sealant for bedding deck fittings must be waterproof, flexible, UV resistant, and, ideally, chemical resistant. Doing the job right starts with using the right sealant. Picking the wrong sealant can cause several problems from early failure to not being able to remove a fitting, portlight hatch etc. without destroying the surface.

 

If you are going to be bedding plastic material or gaskets then silicone is a good solution. Silicone should only be used above the waterline and should never be used on areas that need to be sanded or painted. There are a lot of silicone products on the market, including 3M and BoatLife.

 

Sealants containing polyurethane are a good choice for surfaces above and below the waterline. Popular brands include 3M’s 4200 and 5200. If you need to seal a hole, then polyurethane is a good choice due to it being able to cure quickly and last nearly a decade. However, make sure to not use it on teak or other wood surfaces or from plastic to fiberglass.

 

Another option is marine caulk containing polysulfide like BoatLife Life-Caulk which can last for over 20 years. Products containing polysulfide and can be used above and below the waterline. Unlike polyurethane, polysulfide can be used on wood but does not work well on acrylic. It’s a great sealant for hardware as well. Make sure you apply enough of it for it to maintain a strong grip.

 

Whatever sealant you choose, always make sure your surfaces are clean before application and watch out for the temperature per the manufacturer's recommendations. Spend some time doing some research before you choose a caulk or sealant and avoid dangerous or costly sitautions.

 

You just put a hole in your boat! On purpose of course but now what do you do? Holes allow water into the boat and that’s not the object of the game. But when you have to put a hole in your boat so that you can install a new portlight or run an antenna wire or put in a thru hull fitting for water intake or a transducer or any of the hundreds of other reasons, being prepared with the right marine grade sealant will set you up for success. But there are so many sealants available online at Go2Marine.com, how do you choose the correct one? Factors to take into consideration include, is area to be sealed above the waterline or below it? Are you going to need to replace this part frequently or do you want it sealed forever? Are you going to want to paint over it? There is a boat sealant available for every application, but not every sealer works for every job. Choose wisely.

 

A good marine sealant for bedding deck fittings should be waterproof, flexible, UV resistant, and resistant to chemicals and petroleum products. Doing the job right starts with choosing the correct sealant. Picking the wrong sealant can cause several problems from early failure to not being able to remove a fitting, portlight hatch etc. without destroying the surface. Be prepared to clean up any excess material or spills immediately, once they’ve cured, they are more difficult to remove.

 

If you are going to be bedding plastic material or gaskets around windows and hatches, then silicone is a good solution. Silicone should only be used above the waterline and should never be used on areas that need to be sanded or painted. For applications where you will need to paint the surface after sealing a latex based sealant may prove to be a better option. There are a lot of silicone products on the market, including 3M and BoatLife.

 

Sealants containing polyurethane are a good choice for surfaces above and below the waterline. Popular brands include 3M's4200 and 5200. 3M 5200 sealant is a personal favorite for all applications. It’s very versatile, usually easy to find and has been trusted by mariners for decades. If you need to seal a hole, then polyurethane is a good choice due to its ability to cure quickly and last nearly a decade. However, make sure to not use it on teak or other bare wood surfaces or to seal, plastic to fiberglass. A good technique to save yourself some clean up time and a messy job is to tape and mask off areas you don’t want sealant adhering to, like you would for painting.

 

Another option is marine caulk containing polysulfide like oat Life Life-CaulkB which can last for over 20 years. Products containing polysulfide are great to have around as they can be used above and below the waterline. Unlike polyurethane, polysulfide can be used on wood but does not work well on acrylic. It’s a great sealant for hardware as well. Make sure you apply enough of it for it to maintain a strong grip. Wipe away excess immediately with a damp cloth or plastic scraper.

 

Whatever sealant you choose always make sure your surfaces are clean and dry following the manufactures recommendations for surface preparation before application. Be sure you are working in the correct temperature range for the product as the temperature has an impact on curing time. A helpful hint when working with caulking and sealants, let the full tubes of sealant sit in a warm place like the engine room or galley or just let them sit in the sink or a bucket of warm/hot water for 20 –30 minutes prior to opening, Stay within the manufacturers temperature guidelines of course but warming it up a bit will help it flow easier and make for an easier application. Spend some time doing some research before you choose a caulk or sealant and avoid dangerous or costly situations. And then once you have found the right tool for the job visit Go2Marine .com for the best prices and fast easy shipping.

 

Tips and tricks for using Marine Sealants Question: If a seam is too deep between wooden planks, can cotton be used to partially fill it? Answer: Yes, Life-Caulk or polysulfide type material is much too expensive to completely fill the seam so yes, cotton can be used. Question: Once applied can I remove 3M 5200? Answer: More than likely, the answer is no. There are some very strong chemicals on the market like DeBond, that you can try to use to remove 5200. Question: Can I apply new silicone sealant over an old sealant? Answer: It is recommended to completely remove the old silicone and clean the area before trying to add new silicone.

Tips for Sealing On Boats

 

  1. Question: If a seam is too deep between wooden planks, can cotton be used to partially fill it?

     

    Answer: Yes, Life-Caulk or polysulfide type material is much too expensive to completely fill the seam so yes, cotton can be used.
  2.  

  3. Question: Once applied can I remove 3M 5200?

     

    Answer: More than likely, the answer is no. There are some very strong chemicals on the market like DeBond, that you can try to use to remove 5200.
  4.  

  5. Question: Can I apply new silicone sealant over an old sealant?

     

    Answer: It is recommended to completely remove the old silicone and clean the area before trying to add new silicone.