How well does 303 protect against UV?

I just bought a Wilderness Systems Tsunami 165 (plastic). I plan, at least for a few months (until it gets REALLY cold) to keep it outside at a local marina because I’ll be paddling it several days a week.

I’m well aware of the damage long-term exposure to UV can cause (though I think the degree of damage is somewhat open to debate). So I’ve been thinking of cutting a tarp to wrap over the boat (secured with bungee cords).

But then I remembered 303 “Aerospace” Protectant…and began wondering if covering the boat with a tarp is really necessary if I give it a good coat of 303 every few weeks? I mean, if the 303 really works, then perhaps that’s all I need—and I don’t have to hassle with a tarp before/after every paddle.

So I’m seeking opinions (preferably based on long experience using 303) on how well it stops UV?



Makers of 303 have pointed out that all
UV protectant coatings work by being destroyed. So 303 will not last like a tarp.

I have painted bands of 303 on my Royalex canoe, and also bands of Armorall. These bands remain perceptible for just a few trips. But I don’t know whether some protection is still present.

Perhaps the worst case for needing repeated 303 applications would be a canoe made with epoxy resin and Nylon cloth. Kevlar cloth lasts better in UV, polyester is better still, and glass and carbon are impervious. But the epoxy resin is more susceptible than the commoner vinylester resin, and deserves protection.

The vinyl layer on the outside of Royalex is UV resistant, but over time the surface will get chalky.

My philosophy is to apply 303 or yacht wax a few times a season when I am driving long distances with the boat in the sun. I have boats going back to the 70s and 80s and they are a long way from being destroyed by sun.

Works well
I store my boats outside and under tarps, aslo 303 them 2-3 times a year.

This boat is 12 years old and was cleaned and 303 applied,

Use a uv resistant tarp
It will work fine.

Tarp it
303 works very well, but treating an entire boat frequently takes too much time and fuss (and is wasteful). Covering with a tarp takes seconds to do.

X’s two !
Jack L

Be careful of wrapping.
Wrapping a boat in a tarp might work if it is also in the shade, but it could be like putting the boat in an oven if it is in the sun. As a matter of fact, I would be at least as concerned about overheating a poly boat if stored outdoors in the sun as I would be about UV exposure. My observation is that polyethylene kayaks overheat and warp in the sun long before they degenerate from UV.

For lack of anything better for outdoor storage, I would consider building a well ventilated box and painting it white. Screen the ventilation ports. Such a box could also provide additional security if locked.

24/7 and 365 for 2 years

– Last Updated: Sep-17-13 10:52 AM EST –

There was a time:
I kept a kayak on my car permanently, and I mean
every day it stayed there as my "storage spot",
since I had zero other spots to store the kayak.
Only 303 was used, no tarps, and little shade,
for almost 2 full years in Detroit metro area.

That boat is now over 10 years old, still a bright blue,
thermoformed Dagger Crossover, and doing fine.

Folks that run outdoor rafting companies use it on PFDs
to enhance their lifespan and profits on equipment.

It works, it is versatile, and it has a proven record
in a variety of industries involving water and
thunderstorms - as well as direct sunlight.

Follow directions for Proper application:
Spray on, wipe COMPLETELY dry.
This product does NOT air dry and you can
NOT finish the application properly with
a damp cloth.
You must finish it with a dry cloth or
dry part of the cloth.
If not wiped completely dry, excess, unbonded,
303 polymer remains on the surface.
THIS unbonded remnant will attract dust/dirt.

Overheat and warp?

– Last Updated: Sep-17-13 12:22 PM EST –

My question is less about 303 and more about plastic boats warping due to heat - is it a question of ambient temperature or direct exposure to the sun? I ask as I have the option to create a shaded outdoor storage space on my patio instead of keeping them in our one car garage / wood shop.

If the kayaks are stored on a covered stand outside will the heat of a L.A. summer, where temps often top 100* F, warp plastic boats? My garage stays a good 20* cooler but I have very limited space.


If stand is in the shade …
If you use a UV resistant tarp and it’s in the shade they will be fine. I store mine in a shady area on a fence with a tarp hanging over one side. Air can circulate under the tarp. One poly boat has been stored 13 years this way with no issues.

themoformed Crossover?
Rotationally molded I believe.

How often did you re-apply 303?

Yes - thermoformed

– Last Updated: Sep-17-13 4:02 PM EST –

People that work in the plastic industry use the term
to describe heating a thermoplastic material
and shaping it in a mold.

Rotating is merely an ""additional"" process.
Vacuuming is merely an ""additional"" process.
Blowing is merely an ""additional"" process.
Injection is merely an ""additional"" process.

The Dagger Crossover was made with a High Density
cross-linked polyethylene material.

I applied 303 about 4 or 5 times a year to the boat
and the cockpit hatch cover.
The hatch cover kept snow, leaves, debris out.
Yes, I paddled most of those winters in Michigan.
The kayak got used extensively and I still own it.

2013 pic

Sounds like a well loved boat but,

– Last Updated: Sep-17-13 9:02 PM EST –

I'm pretty sure that "thermoforming" is a more specific term.
From Wikipedia:

"Thermoforming is a manufacturing process where a plastic sheet is heated to a pliable forming temperature, formed to a specific shape in a mold, and trimmed to create a usable product. "
"Thermoforming differs from injection molding, blow molding, rotational molding, and other forms of processing plastics."

It's true, that to fill a mold in any of the other techniques you named, the plastic must be heated, but not as a pre-existing sheet.

(but then I don't work in the industry...)


– Last Updated: Sep-17-13 10:43 PM EST –

The resin pellets are simply extruded into a flat sheet
of appropriate size and thickness .

One raw product comes in a box as loose pellets
the other comes on a pallet in various panels
- SAME raw stuff -.

There are slight pros/cons on additional process
Scroll to end of article to get some insights.

Enjoy the 303 protection on either Poly end product.

Just to be clear
Polyethylene and the plastic used to manufacture what is referred to as thermoformed boats is not the same plastic. Eddyline uses something they call Carbonlite 2000, which I believe is a form of ABS plastic.

Makes sense.

It is not the "same raw stuff"
ABS is not the same as the material in the “poly” bloats. Just try to glue something to both and you will see the difference.

While it might be improper use of the “semantics”, most are using it in a specific way, so “thermoformed kayak” means something specific, as the link above stated.

Yeah, would be nice if all language was 100% correct logically, but that’s not the case here.

I was buying some doors for the house a while back and they called “composite” a very specific door type, even though all doors that are not made of a slab of wood without any veneers and fillers are essentially composites. You can’t change the “industry” slang easy, so use it in the right context to be understood properly…

Willi, I’ve been to both the Perception
and the Dagger factory, back when both were making rotationally molded boats, and neither ever mentioned “thermoformed”.

Thermoform is not logically incorrect for rotational molding, it just hasn’t ever been used. Applying it to poly boats, whether rotationally molded or blow molded of HTP, injects an unnecessary note of confusion. On this board, “thermoformed” refers to a third process which I am sure is familiar to you.


– Last Updated: Sep-18-13 3:35 PM EST –

Thermo - refers to heat, and nothing else

Forming - pretty self explanatory

A thermoset material - needs heat to cure

LDPE and HDPE are great example of crosslinking
--i.e. curing of the thermoplastic via heat so that it
changes its bonding structure into a thermoset

PolyEthylene usually has a lot of "fillers"

Who did what when and how doesn't change the word
A thermo-meter measures heat

Let’s “heat up” this discussion Willi

Am I to believe that when the BIG manufacturers receive their train load of plastic pellets that are to be put in their machines to make kayaks…all those plastic pellets are not created…equal…and the poly butyl’s are not hexagonally cross linked in exactly the same way?

Are there orphaned plastic pellets wandering homeless in the back alleys of urban China just hoping to find a mold?

Oh…what’s our paddling place coming to?