The sun is harsh on lots of things around boats: dinghies, kayaks, SUPs, jerry cans, lights and even just the fiberglass of the boat itself. Things don’t just fade; they degrade, often to the point of breaking. We do our best to protect things!
Admittedly, the best protection is canvas/Sunbrella covers, but we can’t keep everything covered 100% of the time. I mean, I want to use this stuff!
303 Aerospace Protectant is what you need. The product tagline says it all: “SPF 40 for your stuff!” Yep, sunscreen for pretty much anything made of fiberglass, plastic, rubber, hypalon, PVC, vinyl, or leather. It’s not for fabric or suede and it’s somewhat slippery, so don’t use it on non-skid areas! It won’t hurt metal, but it won’t really do anything for it either.
For kayaks and paddleboards, it also helps keep water scum from adhering to them. Unfortunately, I haven’t had similar luck with it repelling barnacles or soft growth on dinghies.
Application is simple. Start by cleaning the item (most things clean up pretty well with a green scrubby-sponge and water; sometimes a little baking soda can help — we try to stay away from harsh chemicals), rinsing with fresh water and drying. If something is basically clean already but has been in salt water, just wipe it off with a damp rag to get any salt off.
Spray the 303 Aerospace Protectant on (for some materials, you need to let it sit for 3 – 5 minutes), then wipe completely dry with soft cloth. That’s it! Re-apply once a month.
One quick warning: 303 Aerospace Protectant doesn’t take the place of keeping things covered or in the shade. Just like sunscreen for your body, it decreases the damage that the sun does — but can’t totally eliminate it.
Possible uses on a boat:
- Kayaks
- Paddleboards, boogie boards, etc.
- Dinghy
- Outboard cover
- Jerry cans (even if covered, be sure to get the areas at the bottom of the cans and around the handles where sunlight can peek under — see photo below)
- Cockpit/helm instruments and covers
- Generator and/or hookah plastic housings
- Plastic exhaust fans and dorades
- Antennas
- MOB poles/LifeSling covers/life raft cover
- Fenders, even if you use covers — get the area at the top that’s not covered
I’ve heard of people using it on their boat itself but haven’t done it ourselves. Seems like it’d be a big job every month, but to keep the fiberglass from going chalky might be worth it.
Re-applying the 303 is part of our once-a-month chores, and I find it takes me a couple of hours to do everything and I’m not working at warp speed. Usually, cleaning the various items is the biggest part of the job and often I discover minor problems that need to be fixed before they become major problems. So it’s a good thing to do not just for the UV protection, but because it makes you really look at a bunch of your gear.
Sometimes you can find 303 Aerospace Protectant at big box retailers (think Home Depot, Lowe’s, Walmart), auto parts stores and hardware stores. I haven’t found it consistently anywhere locally, but can find it lots of places online. I get it from Amazon as they have the best price every time I’ve checked (if you price compare, be sure to check shipping as it can be substantial some places).
I bought a 16-ounce spray bottle one time and now buy the cheaper-per-ounce one gallon jugs to refill it (I find the 16 ounce bottles much easier to use than the 32-ounce ones — my hand doesn’t get nearly as tired — but the 32-ounce bottle is a much better deal). The wipes are handy for areas where you don’t want to get overspray, but they dry out quickly in hot weather. A friend of ours swears by them; we tend “make our own” wipes by spraying the 303 onto a paper towel and then wiping the item. All the following links are to Amazon:
- 16 ounce trigger spray bottle of 303 Aerospace Protectant
- Gallon refill bottle of 303 Aerospace Protectant (equal to 8 16-ounce bottles or 4 32-ounce bottles)
- 32 ounce trigger spray bottle of 303 Aerospace Protectant
- 303 Aerospace Protectant wipes
NOTE: The company is in the middle of changing the label design from primarily dark blue to primarily white. The product is the same in both. I’ve linked to the new packages where available as the other ones are being phased out and I hate broken links!

Carolyn Shearlock has lived aboard full-time for 17 years, splitting her time between a Tayana 37 monohull and a Gemini 105 catamaran. She’s cruised over 14,000 miles, from Pacific Mexico and Central America to Florida and the Bahamas, gaining firsthand experience with the joys and challenges of life on the water.
Through The Boat Galley, Carolyn has helped thousands of people explore, prepare for, and enjoy life afloat. She shares her expertise as an instructor at Cruisers University, in leading boating publications, and through her bestselling book, The Boat Galley Cookbook. She is passionate about helping others embark on their liveaboard journey—making life on the water simpler, safer, and more enjoyable.
Here’s your “Quick Start” to everything you need to know when living on a boat:
Chris&Janet says
We have found applying this with a four inch wide napless roller to be much less tedious than spray. The only time of day we have still air is when it is too humid to apply the spray.
Rebecca Girouard says
We use the 303.
Belinda Wolfe says
We heard 303 is the best way to keep shore power cords flexible and looking like new!! Can’t wait to try it.
Carolyn Shearlock says
Yes, it’s great for that and thanks for the reminder — I forgot it when I was making the list!
Eva De Lourdes Edwards says
Yes, thank you for clarifying SPF. Sounds like a good item.
Marie Holmes says
We use this on our dinghy too. It does a great job.
Anne Ellingsen says
We will check it out
Lee Nicholas says
Have any of you folks ever tried Island Girl wax from Hawaii. I have used this on my
Morgan 384 . Its clear no buffing. !!!!!!! This is not Poly glow stuff.
You use there blue tinted stuff that removes oxide of gel coat just with a rag and wash off.
Rub on island girl clear and you shine more that a year. They have decks for dinks, non skid. I can send ya pix this stuff works.. Its no bargain but there is no work putting it on for the shine. Water beads and reflects for a year..Honest
Anthony says
He must have bought product from one of our resellers. But this is true and can be seen by pics and video on our site. Also Practical Sailor tested our MIRROR HARD™ product against many others and it was one of only two products beading water a year later. Pity they stopped the test, we can now guarantee THREE YEARS!
Pete Smalley says
Great stuff! I buy it by the gallon on Amazon Prime and apply it with a foam roller.
Michael Guelker-Cone says
Great stuff. On our inflatable kayaks. Keeps them from fading and getting brittle.
McTug McGahee says
Great for boating. Also fantastic on auto convertible tops!
Jason Gard says
And it also works a treat on inflatables. Our Hypalon AB is five years old and looks new due to the fact we coat it every two weeks with 303.
Jeanne Krawetzky says
Peter Krawetzky. We should try this in dingy
Tammy Swart says
We just bought a new life sling cover…you’d better believe I sprayed it with 303!
Sarah Silverstein says
What about vinyl clears? Does this cloud them up?
Carolyn Shearlock says
It shouldn’t. In fact, it was one of the protectants that was used in a Practical Sailor test (and did well).
See http://www.practical-sailor.com/issues/37_37/features/Protecting-Clear-Vinyl-Windows_11299-1.html
Peg D says
Can I use it to protect my patio umbrella at home?
Carolyn Shearlock says
If the umbrella is fabric, they make one specifically for fabrics: 303 Fabric Guard
Peg D says
Thanks Carolyn! Just what I needed to know.
Danny Villagoza says
Do you really feel this stuff is more than the typical goop in a bottle that sells for way more than the ingredients? Any specific knowledge of it’s effectiveness? I have some and wonder if it’s just another con in a fancy bottle.
The Boat Galley says
I know that stuff I use it on doesn’t degrade the way stuff I don’t use it on does.
Lindsay Powell Neuber says
We have been using it on our cars. It keeps black plastic area nice and shiny. We need to try on our boat. Do you think it would work on an inflatable paddle board ? It is very difficult to find in hawaii. Glad to see amazon sells it
Ted Reshetiloff says
303 is awesome stuff. Use it on the tubes of your dinghy it will help them last longer.
Patricia Leat says
I use it on everything! Fabric guard, 303 marine.. etc awesome!