Calculating How Much Sealant to Use With Boats Over 12 Feet:


Be sure to check out our Getting Started information before beginning any inflatable repair project!

inland marine inflatable boat repair sealant

One quart of Inland Marine Sealant® is sufficient to seal small leaks on boats 12 feet long or smaller. On boats larger than 12 feet, there is a formula for calculating how much Sealant to use for each air chamber:

The basic rule is: 1/2 ounce of Sealant will cover 1 square foot of material.

The Formula for finding how many square feet of material there are inside your boat is: (Length of the Boat in feet) x 12 x 2 x (Diameter of the tube in inches) x 3.1416 -:- 576 = Number of ounces of Sealant needed to treat the boat.

This number, divided by the number of air chambers gives the amount of Sealant needed in each air chamber.


A 15-foot boat with 22-inch tubes and three air chambers: 15 x 12 x 2 x 22 x 3.1416 = 24,881.47 square inches total area. 24,881.47 -:- 576 = 43.2 ounces of Sealant will be necessary to treat this boat. Divide 43.2 by 3 air chambers and each chamber will require about 14 ounces. It is recommended that you plan on two applications; use about 8 oz the first time and about 6 oz for the second treatment.


There are a couple of options available to those who own inflatable boats too large or heavy for one person to tumble. One option is to call several friends and ask their help. (When choosing this option, always remember the Cardinal Rule of Boat Repair: When you're out of beer, you're out of friends.)


  1. Deflate the boat and inject the Sealant in each air chamber as outlined in the standard instructions.
  2. Re-inflate the boat to rigidity.
  3. Have two friends on each end of the boat. (Now you're management.)
  4. Raise the stern to about 45 degrees and hold for about 10 seconds.
  5. Lower the stern and raise the bow for 10 seconds.
  6. Turn the boat (rotate along its length) about five degrees and raise each end again.
  7. Continue rotating the boat 5 degrees at a time and lifting both ends until the boat has been turned completely over.


(Your friends are now casual observers...they can furnish their own beer.)

  1. Place the boat to be treated flat on the ground.
  2. Deflate the boat and add the Sealant following the standard instructions.
  3. WITH THE BOAT STILL DEFLATED, walk the Sealant around the air chamber, that is, step on the air chamber while it is deflated pressing the top half of the air chamber firmly onto the bottom half.
  4. Start at the valves and work your way to the ends until you are sure all the top half of the chamber has contacted the bottom half. (Another alternative to walking the boat is to use a garden type roller to help spread the Sealant.)
  5. When you are sure Sealant has made contact with the entire interior of the air chamber, walk it again!
  6. Now you're ready to re-inflate the boat to RIGIDITY.
  7. Wait 3 hours, then inflate the boat to full pressure and check for leaks.
  8. In the unlikely event that there are still leaks, re-treat the boat using only 1/3 the amount used the first time. Make sure the Sealant gets to the leaking area. Do not allow the Sealant to pool in any one area.


treating seams

Inflatable Boat Sealant Kit Stops Slow Leaks!

Inland Marine Sealant® is specially formulated for use with inflatable boats, rafts and tow toys. This sealant forms a bond with the interior fabric of the inflatable, stopping or "sealing" slow leaks and preventing future leaks from developing.

In one easy step, leaks are cured from the inside, which are virtually impossible to find from the outside. Inland Marine Sealant is the only product of its kind which allows for future deflation of your inflatable (for storage, etc.) without the skin sticking to itself and making re-inflation virtually impossible. This is why Inland Marine Sealant has earned a 5-Star product rating from West Marine™, and is has been used by the US Navy and Yachters worldwide since 1986.

If you are having a difficult time locating the leak in your raft, kayak, tow toy, or dinghy, you need to use Inland Marine USA Sealant, because our Sealant isespecially helpful in fixing those difficult slow leaks that are not easy to find. Our Sealant provides a strong bond that should last for years when applied according to the easy instructions.

It will seal the leak(s) and keep your inflatable firm for years to come. And Inland Marine USA Sealant can be used multiple times, so if your inflatable develops a new leak weeks or years from now, you can use the sealant again!

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How can something so thin be so strong?

Inland Marine USA Sealant flows faster than water. The viscosity of our sealant was specially formulated by our chemist to repair inflatable boats and make them reliable – even in rough seas.

You might compare our Sealant to a sheet of Kevlar. Kevlar can stop bullets; a 2 mil thickness of Inland Marine USA Sealant can stop air up to 90 PSI. In tests, we have even sealed soccer balls and used them in games, bounced them on concrete, and kicked them as hard as we could without leaks.

Since 1986, our sealant has been used by boaters around the world to repair inflatable boats of all kinds. The product is used by professional raft repair companies, US Navy Seals, and individuals like you for inflatable boat repair.

Some manufactures even use Inland Marine USA sealant to repair boats in their Quality Assurance Test. Slow leaks can be difficult or even impossible to find, but our sealant will solve all your slow leak problems in minutes!

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Liquid Rubber® for Re-skinning Inflatable Boats,
Kayaks, Rafts and Tow Toys.

Inland Marine Liquid Rubber® is truly a unique breakthrough in the rubber field. For the first time we are able to get 100% pure EPDM liquid-form rubber to cure without vulcanizing (applying high heat and pressure at the same time, which is what the manufacturer did when your boat was made). The consistency of honey, Liquid Rubber "paints" on to form a seamless, leakproof membrane of pure rubber. Available in black, gray or white, one quart will renew a 10-foot boat with a coating 5-7 mils thick, when applied according to the easy-to-follow instructions. (If you can paint a wall, you can do this!)

Since the original skin of most inflatable boats is 5-6 mils thick, Liquid Rubber truly renews and restores your boat to its new condition, even if your boat has lost some of its outer skin and even if the fabric is showing through. Years of use can wear the outer surface of your inflatable; abrasion and UV exposure can make your boat look old and worn-out and can cause slow leaks. Use Inland Marine Liquid Rubber to spot-repair or reinforce those heavy wear spots before they wear through. Or, re-skin the entire boat with Liquid Rubber to add years of serviceability to your boat. Liquid Rubber can be used again and again in the future to restore your boat's original look. Available in three (3) colors to help match your original inflatable skin color.


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Can I paint Liquid Rubber?

Liquid Rubber comes in three colors. Grey (the color of many new inflatables), Black, and White. You may not want or need to paint your inflatable after you use Liquid Rubber to re-skin it. However, if you do want to paint it, you should use Inland Marine USA’s Top Side Paint.

Our Top Side Paint is mixed with our Sealant to provide an extra bond and seal for your inflatable. Elasticity is important when painting an inflatable boat and Inland Marine's Top Side paint exceeds these requirements. Your inflatable boat will expand and contract when it is exposed to the sun and shade. If the paint you use does not have the elasticity to adjust to these changes, it will crack and peel. Inland Marine USA provides Top Side Paint in seven (7) colors so you can paint your boat, or creatively make it unique and easier to find when in a busy port of call.

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Inland Marine USA Top Side Paint

This is not the paint your Daddy used on his boat! (And not anywhere close to the paint sitting next to it on the shelf at your marine store.) Inland Marine Top Side Paint® is specially formulated to have the elasticity and UV resistance required for use with inflatable boats. Because inflatable boats expand in the hot sun and contract at night in the cooler temperatures, constantly flexing, ordinary paint or vinyl stick-on numbers will not stay on an inflatable boat for more than a few weeks. But we don't stop there! We mix our Sealant in our Top Side Paint to further enhance the airtight integrity of your inflatable.

Inland Marine Top Side Paint is available in Red, International Orange, Yellow, Royal Blue, Grey, Black or White. (With changing weather conditions in many areas boaters frequent, International Orange or Yellow makes it easy to find your dinghy at the dinghy dock if a "Rum Front" comes through while you're ashore.)

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The first step to repairing or restoring your boat is to make sure it holds air correctly. All inflatables, regardless of manufacturor, develop porousity problems over time. This simply means small pin-hole leaks develop in the fabric or seams that can not be seen from the outside. When this happens, the air chambers will typically leak air slowly over a day or two. These pinhole leaks must be repaired before applying any top-coating products such as Liquid Rubber or Topside Paint, or down the road, your boat will develop air bubbles under the top coating.

For this reason, we highly recommend you treat your boat with Sealant as a first step. Sealant is an internal sealer that has been used by the US Navy and Coast Guard since 1985 to cure porousity problems. We also recommend re-treating older boats every year or two as new porousity problems will develop over time.

Remember, inflatable boat repair of kayaks, rafts, dinghies, or tow toys is dependent on proper preparation of the surface area. If you do not clean your inflatable as instructed, you are wasting your time and the products you have purchased.


When you are sure your boat is holding air, the next step is to be sure you are working with a clean and dry surface. If possible, take your inflatable boat or other repair item into a room with low humidity, or perform the repair when humidity is below the manufacturerer's recommendations.

Check out our Cleaning and Preparation Products, specially formulated to prepare your inflatable for patches, rubber and paint!

Special Note to PVC boat owners:

For the past several years, many boat manufacturers have been using PVC material from China. The reasons for this vary, but usually include cost as the main factor. As a result, the frequency of boaters reporting a ‘breakdown” in the material has risen drastically. The PVC material will actually start to decompose, resulting in a sticky or tacky surface, especially when exposed to intense sun like we have here in south Florida. If this condition exists on your boat, be very cautious in using any top coating product as it may not dry and cure properly. Always test a small area first.