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What Are Stringers On A Boat?

If you have bought yourself a boat but you are not completely familiar with all the ins and out that comes with maintaining and caring for your boat, then don’t worry – you are not alone.

It is surprising how many boat owners there are out there who are not 100% familiar with every nook and cranny of their boat. Owning a boat and caring for one can be a real learning experience and you are always finding out new things about your boat every time you board it.

So what about stringers?

You may have heard this term knocked around the docks a few times but what are they actually and how do you maintain them? For everything you need to know about stringers on a boat, then just take a look below.

What Are Stringers On A Boat

What Are Stringers On A Boat?

Boat stringers are lengths of wood typically found in older boats or prefabricated fiberglass molds in newer boats. They are part of the hull system and are installed in a grid to create a support structure beneath the boat’s deck.

They strengthen the hull of your boat and serve as a foundation for the deck and bulkheads. Stringers are laid longitudinally and extend from the bow to the stern of your boat, supporting the whole length. Frames are then run between the stringers to give additional strength and support.

Together, the frames and stringers make up the stringer system. They are like joists for your boat – where joists hold up the floorboards in a house, stringers hold your deck.

They are a kind of old fashioned design, but a lot of boats today still have stringers – they’re just made from different materials like aluminum. Traditionally, wood was used to make stringers strong and flexible.

However, wood does have an issue that makes it a not so popular material today – it has poor durability. Wood can rot when it is exposed to water and moisture, so wooden stringers constantly need replacing.

Today, most newer boats use aluminum as it does not rot and is still very light and resistant to rust. Some boats even have stringers made of fiberglass even though it is a heavier material. But no matter what material they are made from, you can probably find stringers on nearly every single boat out here.

This is why it is important for you to not only just know what a stringer is, how to look after them and how to replace them. Unfortunately, boat stringers often need replacing and repairing as they will become stressed over time and start to degrade.

If your stringers are made from wood, then things like rot and woodworm can really damage your stringers. Without properly functioning stringers, your boat can literally just fall apart. Without that core support system, your boat can’t function properly and that will cause a lot of inconvenience for you.

How Do You Know Your Stringers Need Replacing

Tell-tale signs of stringer damage on deck includes holes or gaps in your decking. If you notice that there are areas of your deck that are not sealed, then it is very likely that water has gotten down into your stringers and is rotting underneath.

Eventually, your deck will start to sag and there will be areas on deck that do not feel secure to stand on any more. Even if you have fiberglass decking, water can still get through your deck.

Water can cause deck delamination, which occurs when the fiberglass cloth layers and resin start to come apart. It only takes one little hole to affect the entire stringer system – so take good care of your deck and regularly check for gaps or holes where water can leak through.

You can always check your stringers yourself. Lift up the hatch to inspect underneath your neck. If your boat does not have a hatch, then you will have to cut an inspection hole yourself. Then, you can thoroughly inspect your stringers.

While inspecting your stringers, check for signs of structural damage. If one area is not looking up to scratch, then it is safe to say that other areas will be affected too. Remember to be thorough so you won’t miss any small signs of damage and you can catch the issue early before it gets worse.

You should also inspect the core of your stringers and check for damage there too. If you have wooden stringers, then rot and damage will be really easy to spot.

Ook for cracks or fractures in the wood, and any small brown spots. These spots are a sign that water has gotten into the wood and is starting to weep out. For fiberglass stringers, look for a break in the encasement.

How To Replace Your Stringers 

If you have wooden stringers, then it is recommended that you just replace the whole stringer as any damage can easily extend through the whole structure. 

However, when it comes to fiberglass stringers, you can replace the stringers by sections. The damaged stringers can be removed and replaced while leaving the undamaged stringers where they are. 

To replace your fiberglass stringers, you will first need to sand down your new ones and mark the position of the old stringers so you know where to put the new ones.

Remove the old stringers and core, then build and bond the new core with a resin and hardener mix. Push the new stringers in and clean up any epoxy that seeps out before it has time to harden. Then, replace the fiberglass hats or skin over the top and you’re done! 

When It Comes To Buying A Boat

If you have decided to buy a used boat, then you definitely need to check the condition of the stringers before you seal the deal. The last thing you want is to sink thousands of dollars into a boat only to watch the boat itself sink a few weeks later because the stringers were rotted and you did not have time to replace them. 

So, when you are checking out a boat you are considering buying, ask the owner if you can check the stringers visually. Even if they look good, ask the owner when was the last time they had the stringers replaced – it might be that they will need replacing in a year or two.

Their answer will also give you a good idea on how well they have checked and maintained the boat. If you are unsatisfied with their answer about the stringers, you should begin to wonder what else they haven’t been taking care of.

You will also want to check for  plywood in the stringers. Some older boats used to use plywood frames with fiberglass hats placed over them. Check if the frame was made from plywood and if the plywood was entirely encapsulated in fiberglass.

If not, then it is likely that water has gotten in and started to rot the wood. Check for any bare wood and see if the wood has been covered with resin-painted fiberglass tape.  Also, while you are on deck, check for any gaps and holes in the deck like you would if the boat was yours.

Sometimes, owners who have plumbing or wiring installed on their boat may not have properly sealed the holes with resin. If they haven’t, then it’s a sign that the stringers underneath will not be in great condition.

And finally, always trust your gut. This is a given when it comes to buying second hand boats anyway, but you should still remember that if you have a bad feeling about a boat or its seller, it is completely fine to walk away.

You may end up saving yourself a lot of money and stress. If you don’t trust what they are saying about their boat, or what you are seeing contradicts what they are insisting, then just don’t take the risk and walk away.


So that is everything you need to know about stringers on your boat. 

Stringers can be found on nearly every boat out there. They are an integral part of the hull support system, and are what helps hold your hull together while supporting your deck as well. They are often made from fiberglass or wood or even aluminum. 

Over time, they become stressed and weaker due to damage. When you notice that your deck is beginning to sag or feel unsafe, it is time to replace your stringers. Replacing your stringers can be easy once you know what you are doing, just remember to check them regularly for damage and rot. 

Now you know what your stringers are and how important they are when it comes to the structure and support of your boat, why don’t you go check them right now? Hop on out and inspect your stringers so you can sail your boat confidently knowing that it is not about to start falling apart. 

Lucas Jones