deep scratch

Advice
#1

I put a deep scratch ( gouge ) in my plastic necky looksha. Would like to fill it. Any ideas ?

#2

is it more than cosmetic?
Most scratches and gouges in polyethylene kayaks represent only cosmetic injury and don’t really substantially weaken the boat.



If you feel that the damage is sufficient to compromise the strength of the hull thermal welding is probably your best bet. This requires some scrap polyethylene material, a heat source, and some flat metal implement like a putty knife or flat head screwdriver. In addition you might need an inexpensive scraping implement to “gutter out” the gouge a bit and smooth any rough edges. A good heat gun or a propane torch or a purpose designed plastic welder (as sold by Harbor Freight) can be used as a heat source. You could check with Necky to see if they can provide you with some color-matched polyethylene welding rod.



There are a number of DIY explanatory videos on youtube that demonstrate the process. Most of these describe repair of through-and-through cracks but the method is the same.



Here is one:

http://www.youtube.com/watch?v=_muVBfAMRT0&list=PL63641D4EAEC8591B



and here is another:

http://www.youtube.com/watch?v=5bos4lfOA3k



G Flex epoxy is one of the few adhesives with will bond reasonably well to polyethylene if used exactly according to directions:

http://www.youtube.com/watch?v=2a5RlcP-4JE


#3

Try this …


http://neptunesrangers.blogspot.com/2013/11/permanent-plastic-kayak-scratch-repair.html



I think one of the boats is PeterCA’s if I remember correctly. Maybe he will weigh in.

#4

single layer polyethylene …

– Last Updated: Feb-02-14 10:31 PM EST –

...... if the scratch is deep (say about 1/2 thickness or close) , and if it's in an area that will be subjected to regular flexing (like the bottom) ... then it's probably a good idea to reinforce and/or plastic weld fill it back up .

Welding as discribed already is the standard precautionary for bad (deep) scratches .

A reinforcement patch on the inside is a layer of fiberglass cloth and resin mix . G-Flex always has good reviews on poly . Light sand and flame the surface for best adhesion before apply a patch .

The plastic has become thinner in the deep scratch , constant flexing , extra wear , some brittleness with time can cause it to crack through . Fixing it now is probably better than later after a full crack through .

There's some here who have done the welding many ways and many times , maybe they'll kick in .

I've never owned a single layer polyethylene , so have never had to fix one , but they do it all the time .

#5

yes, my boat
Yes, the red and orange boat is mine. But that doesn’t make me an expert on the process, just on scratching boats…



Truthfully, unless the scratch is so deep you can see the other side, or if it left an avulsion of plastic that may catch water, I just leave it. if an avulsion, I may try to melt it back, or just cut it off.

#6

more info
This pdf file from Wilderness Systems describes repair methods for rotomolded polyethylene boats.



Applying a cloth patch (using either fiberglass or aramid) with G Flex on the interior of an area of severe damage is certainly an option worth considering. In order to do so you have to be able to access the interior of the boat at that location, not only well enough to apply the cloth and epoxy, but also well enough to pretreat the polyethylene by flaming the surface with a propane torch. If you don’t do this, G Flex will not bond satisfactorily.

#7

thanks
a lot of good ideas. Tarp sounds easiest & safest. have to find some orange tarp as the kayak color is sunburst

#8

P-tex?
I used to manage a ski shop and we used P-tex sticks (a flat stick of polyethylene that you melted with a torch like sealing wax) to patch deep gouges in ski and snowboard bases. Has anybody ever tried this with roto kayaks or knows why it would not work? Stuff is cheap at ski shops, less than $10 usually for a multi-pack. You melt a bunch of it into the cleaned out scratch or ding and then, once it’s cooles, carve it smooth with a metal scraper.

#9

cosmetic vs. structural …

– Last Updated: Feb-04-14 1:32 PM EST –

..... if you're NOT concerned the deep scratch (gouge) is in an area that might crack later from flexing , then a cosmetic fill is all you want . Melting a poly tarp to fill with is a cosmetic not a structural .

You could just as well heat the putty knife and re-smooth with the putty knife and scraper for cosmetic .