spongy boat floor repair tips

Spongy Boat Floor Repair Tips (5 Step Guide)


Spongy floors in a boat can seem funny but really weird. But this is a really common scenario for many of boat user. But there are specific repairs you can follow to fix this issue. 

So, what are the spongy boat floor repair tips?

To repair your spongy boat floor, you need to change the wood under the fiberglass. So cut the fiberglass and scrape the wood off. Then clean and sand the area. Apply glue on the boat and the attaching board. Finish with putting the fiberglass back on. Let the glue dry before you headout again. 

So, that was a quick look at the whole process of the repair. But there are more details to learn about. So, let’s get right into it!

What Causes Spongy Boat Floors?

Boats are not supposed to be spongy. Modern days boats are made with wood and fiber glasses. Fiber glasses are really durable. It’s more like plastic than anything. So it doesn’t rust or rot in the water. 

That is why the wood is covered by fiberglass. So, the water doesn’t get in touch with the wood and rot. But if there are any holes which you left open, can cause the wood to rot. 

And that is why the wood can inflate and cause the spongy effect. Though it is really easy to fix. Check below, where we have discussed the whole process in 5 steps. 

How to Fix Spongy Boat Floors?

Before you start working, you need a few things to do this job. You’ll be needing a saw to cut through the fiberglass to the wood. Glue to attach everything back. A new wood panel. And your skillset to do the job. 

So, if you have everything around you, let’s get started!

Step 1: Cut the Fiber Glass Off

Firstly, check where the sponge floor is on the boat. You need to cut the spongy area on the boat with the saw. Make sure to set the depth level of the saw to the wooden part of the boat. Otherwise, the saw can cut right through the wood and to the boat. 

If you don’t have a saw to cut your boat with, then check the links below. Both of these saws are highly capable and you can use them in your other projects as well. 


Both of these saw are really powerful. Also, it hase guard which can protect your fingers from chopping it off. But always be careful around saws. 

Although, before you start cutting, make sure to remove any important parts. Such as is the it’s spongy around the steering wheel, remove the steering wheel first. Otherwise, it can get damaged. 

Also, before you start cutting, make sure not to damage the fiberglass on top. Most of the time the fiberglass can be reused. The fiberglass doesn’t rot like wood. So, often cases the fiberglass is not affected. 

But if water has destroyed all the wood, you can cut right through. But make sure not to cut through the fiberglass which is under the wood. You’ll be needing that piece of fiberglass when you apply the new wood. 

Step 2: Remove All the Roten Wood

When you remove the fiberglass, you can expose all the rotten wood under it. Using a shovel in this scenario can be really helpful. Use the backside of the shovel and push on the rotten wood. 

Often cases not all of the wood is rotten. Check where the water came from. And on the basis of that, you can determine how much wood you need to scrape off. 

If the water came from the top, start scraping until you see dry wood coming out. But if the water came from the bottom, you need to change the wood of the whole area. 

Step 3: Pressure Wash and Sand the Area and the Fiber Glass

After you scrape off all the wood, you have to pressure wash the whole area. The pressure wash will ensure there is no glue or wood sticking around. Make sure to blast water in the corners. Usually, glue sticks in the corners and in the sides. 

After you wash the whole area, you also have to sand the shole area. The sanding is necessary because otherwise, the glue will not stick to the wood. Also, the fiberglass has to stick on the wood. So scraping with the sand paper is necessary. 

Also, remember to dry the whole area before you apply glue. Water and glue dosen’t attach well. So, it won’t stick that well. The glue will lose some of its effectiveness. You can dry the area with a towel or heat gun. Make sure to dry the corners. 

Step 4: Apply Glue on the Both Parts

Now that the area is clean, get wooden board which you need to stick back. You need to replace the wood in the rotten area. So, go to the hardware store and bring a wooden board for boats. 

The type of wood you choose can also determine th quality. Make sure you are using wood which are meant to use in boats. These woods can stand against water a bit more than other woods. 

Not cut the board with the saw according to the size you need. You can get the exact size if you use the measurement of the top fiberglass of the boat. 

Now, apply glue on the fiberglass and the wooden board. Make sure to spread the glue on the board with a scraper. This way the coat of the glue will evenly spread. 

Let the glue become sticky, and then push the board on the area. Afterwards, push the fiberglass on top. 

Step 5: Attach all the Pieces Back Together

Now that all the pieces are in place. You need to push down so it sticks to the boat. Also, you can put some heavy things on the top so it pushes down on the boat. 

Make sure you apply glue in the gapes in the corners of the boat. This way the glue will able to fill any of the gaps in between. Cause in future if there are any cut outs, water can sip in. And cause molding and rotting again. 

Fixing the floor can be a good solution. But aesthetecally this is not a good solution. Changing the boat floor can be a better option if that is one of your concern. 

The glue will take 12 hours to 24 hours to stick. After that you can take the boat for a ride. And that was everything about how you can fix the sopngy floor on your boat. 


How does Adding Foam to the Boat Help?

Floating foam can increase the sink-proofing, temperature control, adn also soundproofing. You can use foam on your boats on the gaps or in hollow spaces of the boat. 

What Glue should I use to Attach FiberGlass?

Using glues such as fiberglass fusion adhesive is best in this scenario. These glues can stick on any polyester area. Also, the glues doesn’t require that much of a surface preparation. 

How Long does it Take the FiberGlass to Stick Properly?

Usually, the fiberglass glues need minimum 12 hours to 24 hours to stick. Also, the amount of glue matters. The more glue you use the longer it will take to dry. Pressing down on the glued area can speed the process up. 


So, that was everything you needed to know about spongy boat floor repair tips.

Always wear gloves and eye protective goggles when working with tools. Also, make sure the glue sticks properly before you head out. 

Goodluck with your boat!

Leave a Comment

Your email address will not be published.

Scroll to Top