boat cover support, that INFLATES

No more sagging covers, water pooling, musty smells, or unwanted pests. SwellUp inflates to keep your boat cover tight, ventilated, and fresh—with a 30-second setup.

Be honest… how well have those support poles really been working for you?

Patent Pending

Buy Now

What is SwellUP?

Our Solution

You know those tension pole’s that you put under your boat cover to keep it tight? Great, same page.

Got them in place and the cover tight? Perfect, we’re ready for the rain in the forecast tonight.

Sleep tight, don’t let the…Let’s just fast forward to the morning. That rain was more of a storm. Your pole tipped over or was off center for the hundredth time and now your boat cover is full of water, again. Hope it didn’t rip on the windshield with all that water weight. Grab a bucket, start bailing; maybe building that DIY PVC pipe frame doesn’t seem so bad. Avast! Before you spend an hour at the hardware store and another hour building your custom frame, you may want to check out the Swell by Batten Down. Doesn’t tip, 30 second setup, peace of mind. It’s the last tention system you’ll buy. Read on, Cap’n.

Frequently asked questions

Got questions? We’ve got answers. Whether you're trying to figure out how to keep that boat cover snug, curious about our inflatable cover tensioners, or just looking for tips on keeping water from pooling up, you’re in the right place.Didn’t find what you’re looking for? No problem—just reach out. We’re always here to help!

Read All FAQ's
  • How does the SwellUP work?

    SwellUP works a bit like magic, but we’ll call it science so we don’t freak anyone out. It uses a unique system with a storage base and inflatable structure (yes, inflatable) to evenly tighten your boat cover across the entire surface. Water pooling? Not on SwellUP’s watch. It can’t tip over, and don’t worry about getting it perfectly centered. It keeps your boat cover secure and free from rips or tears in all kinds of weather. Oh BTW, that’s not all… #3 is worth a read.

  • What else does SwellUP do?

    Glad you asked. Swell doesn’t just keep your boat cover tight. Oh no. It also has air circulation powers, keeping a handle on mold & mildew while keeping your boat smelling fresh. As for pests? Wasps, mice, and spiders are not fans of what Swell is serving for dinner; Constant air circulation, subtle vibration, and a fresh smelling fragrance booster. Turns out most pests don’t like minty smells, airflow, or vibration. In summary, this thing keeps your boat smelling like a spa, helps prevent mold/mildew, prevents water from pooling on your cover, and deters pests. You’re welcome.

  • Why should I use a tensioner with my boat cover?

    Simple: it keeps things tight. A good tensioner like Swell stops water from pooling, which is a short way of saying it helps your cover avoid damage, rips, tears, mold, or mildew. Plus, it extends your cover’s life—so you don’t have to replace it as often. Basically, it’s the boat cover upgrade you didn’t know you needed.

  • What types of boats can I use SwellUP with?

    SwellUP doesn’t play favorites. Fishing boats, pontoons, bowriders, speedboats—if it’s a boat, SwellUP is here for it. It’s adjustable and customizable, so no matter your boat’s size or shape, SwellUP has you covered (pun intended). Have a boat that this won’t work in? Let us know, send us an email and we’ll work on a custom solution.

  • Can I use a SwellUP while I tow my boat on the road?

    Can you? Sure, if you want to drive down the highway with your boat cover on, go right ahead. Should you? Hmm… it is the expressed opinion of Batten Down that you do not tow your boat down the highway while covered. Most boat covers don’t like high winds and you might be inviting rips and tears.

    On a completely unrelated note… if you plug Swell into a small (say 100 watt) inverter that is connected to your boat battery, you no longer need to be attached to an extension cord. Since you now have a mobile setup, you may be wondering how fast you could go before the wind pushes the inflatable down. Who knows, we don’t recommend Swelling and driving, remember. I bet it would inflate back up even if you did go too fast though. If someone was going to try, maybe strap the cover down tight, crank the fan power controller up to 11, and close the vents on the inflatable. Then, just maybe, Swell would hold up at highway speeds. Hard to say, we haven’t tried…ok, we tried, it worked, but don’t do it. The warranty probably doesn’t cover that.

See it In Action

Shop Now

Hear What Others Have To Say

Pretty happy with this system. New boat owner here, and this seemed like the obvious choice when looking at all the options available. Couldn’t find many high rating reviews for the support poles. Straightforward to use and glad I don’t have to go through all the struggles I read others going through. I like that it does more than just tension the cover too.

Taylor J.

20’ Malibu, Response

I have been dealing with Boat Cover Support systems for over 50 years and this is by far 100% the best. It can be installed in less than a minute. I’ve had mine installed for over five months now and no evidence of mildew, insects or rodents. Without a doubt, the best accessory I’ve ever bought for any of my boats throughout the years.

Mark Pass

19 foot Mastercraft pro star 190

I love the ease of use of this cover tensioner. Just put it in position and plug it in. Works perfectly with my boat and fitted cover. No more bailing water off my cover or out of the boat when storing it. 5 stars

Chuck C.

20 Ft Center Console Aluminum Bay Boat

I’m so glad I bought this inflatable, cover tensioner. It has completely solved the problem of water pooling on my cover and musty smells when left covered for a long time. As a bonus, it keeps pests like mice and wasps from getting underneath. I haven’t had any wasp nest issues since installing it, which is a massive relief. It’s sturdy, easy to use, and has held up through several storms. Would recommend it.

Clarke S.

21’ Ranger, Bass Boat, Z521

After dealing with water pooling and an invasion of wasps under my boat cover, I decided to try this cover tensioner… It works. My cover now stays tight, no poles that can tip over. Noticeable decrease in wasps and haven’t noticed any mice.  It was easy to use, and the peace of mind it provides is invaluable. If you want to protect your boat from water and pests, this is the product for you.

Mike H.

21’ Four Winns, H210

This inflatable is amazing! It keeps my boat cover tight, so there’s no water buildup, and it also acts as a barrier against pests. I used to find wasps nesting under the cover and mice trying to tear up my seats, but not anymore. It’s like having a dual layer of protection for my boat. The product is durable, easy to install, and has made maintaining my boat so much simpler. It’s worth every cent.

Collin F.

24’ Lowe, Pontoon

This little unit has exceeded my expectations so far. Batten Down’s Swell, is not like the blow up Halloween decorations. It is crazy powerful. I have a heavy sunbrella cover and it holds it up with the fan at less than 1/4 power with all straps cinched down. Should help with airflow to prevent mildew and mold. Look forward to checking it in a month or so. Nice work!

Matthew P.

2016 Key West 239 FS 23’9”

This thing has been an absolute game-changer. Not only does it keep my boat cover tight and free of rainwater, but it also prevents pests like mice and wasps from setting up shop inside. I’ve noticed a huge decrease of wasps in my boat since installing this tensioner. Installation was quick and easy. Highly recommended.

Rob B.

24’ Avalon, Pontoon

This undercover inflatable is a lifesaver. Before using it, my boat cover would always sag and collect water after any rain. Now, the cover stays tight and dry, even during heavy downpours. It was easy to install, and the quality is good. I’ve had it for a few months now, and it’s still going strong. Love the constant air circulation and fresh smell it keeps. This is a must-have accessory for anyone who wants to keep their boat and cover in top shape!

John C.

20’ Bayliner, Capri

I’ve been dealing with rainwater puddling on my boat cover for years. After trying several DIY fixes, I decided to give this inflatable thing a try. Yeah, worth it! It’s easy to install and does exactly what it’s supposed to. My cover stays taut, and I haven’t had any issues since I started using it. It’s made boat maintenance so much easier, and I’d recommend it to any boat owner. Side note, pest deterrent is a big plus.

Brian C.

21’ Mastercraft, Maristar

Our Blog