Foam floats, and boats can sink, so why not fill boats with foam?
It’s a super common question I get from boat owners, as many of them want to add foam to their boats.
There is also some confusion on the topic, it’s not as magical some make it out to be. Also, this post is more about recreational boats, as some larger boats will do things differently.
Will Adding Foam Help Your Boat’s Buoyancy?
Some boats and jet skis manufacturers do add foam to them, but it’s not to help the boat with its normal buoyancy.
The foam you see in many boats is there in case the boat or jet ski takes on water, and the foam keeps it from fully sinking too quickly. If there is no water in the hull, then the foam is not helping with anything.
The placement of the foam is interesting too. Most boats and jet skis will place the foam in the front/center so the nose sticks up when it starts to sink and can easily be grabbed by the bow hook and towed away.
Unless your boat is sinking, the foam is not doing anything. But this does bring up the question of if you “should” add it if your boat doesn’t already have foam?
Don’t Add Foam
Generally, you should NOT add foam to your boat if it did not come with some from the factory.
The expanding foam makes a mess, could expand in some places too much and damage parts of your boat, and over time becomes waterlogged.
I know it sounds backwards, but foam breaks down overtime and has pores that will absorb water, which makes your boat heavier.
You honestly would be better off stuffing your boat with life jackets, pool noodles and other things that float, then add foam. At least with this stuff, it doubles as life-saving devices, and you can never have too many of them.
Foam Not Placed Right Can Make Things Worse
Adding foam to a boat that did not have it built with it in mind can lead to issues that many people miss.
I see far too many people add foam to the bottom of their boat. They forget the foam is for when the boat sinks, not for everyday riding. So, when the boat does take on water the lightest part is now the bottom of the boat and thus the boat flips over and often violently. This improper use of foam can really hurt people and throws off the engineering of the boat.
Bigger Boats & Foam
All types of boats can come with foam from the factory, even small jet skis all come with foam in the bow.
I’m not a fan of adding foam to a boat, but there are times when it does make sense, and that is with larger boats or houseboats.
Some larger boats will skip the foam and use chambers to air lock the boat to keep it afloat. Some houseboats will have foam added to them because people live or spend a lot of time on them.
Foam Does Not Make A Boat Unsinkable
The reality is that nothing is unsinkable!
The foam in boats will buy you time to get help, but given enough time, the boat will fully sink.
Newer style of foams hold up better and don’t trap water, but it’s still not perfect and nothing is unsinkable.