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Thread: uhmw repair?

  1. #1

    Default uhmw repair?

    is there any way to repair the uhmw on my jetboats bottom where it is gouged or small chunks are missing?

  2. #2

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    Quote Originally Posted by colorado jet boater View Post
    is there any way to repair the uhmw on my jetboats bottom where it is gouged or small chunks are missing?
    Yes it's possible. The damaged material would have to be cut out and a new piece glued back in its place. A special welding iron is then used to seal the joint. Sending you a pm.

  3. #3
    Member OzAK's Avatar
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    As HG said, you can "glue" a patch in place but unless you use the particular type of UHMW with a "fabric" molded into one side of the plastic during production, it will not mechanically bond with the structure very well. Mechanical fasteners are the surest way of keeping it where you want it but you may or may not want to drill holes in your hull or possibly not be able to get at the back side where you need the nuts and sealing washers. If your bottom is at least 3/16" you could entertain drilling and tapping as well. There's no real one good easy effective answer because UHMW is a very unique animal in the plastic world. As for the welding of UHMW with whatever method you may choose to try and bond it with heat, you'd better pack a lunch and bring a flag of truce because it will not bond with itself in the liquid state. I've tried it with the black, absolutely not possible. It was like trying to glue an oyster to wet glass. Perhaps the white virgin material will, but I'd be willing to bet not. You may get it to look like it is sealed or smeared together at the seams but you should not trust it to actually be bonded together with any strength. So far I've had my best results with 3M 5200 on roughed (24 or 36 grit) up hull, I didn't have the fabric impregnated UHMW so I ground on regular stuff too with a 24 grit disc, then applied the 5200, then added weld-on washers for my mechanical fasteners that don't penetrate the hull. These also allow your UHMW to expand and contract without being encumbered. That stuff has a coefficient of expansioncontraction that will make your head spin compared to aluminum. Hope this helps, Oz

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    Member Gerberman's Avatar
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    I weld UHMW with my extrusion welder using UHMW rod and standard compressed air. The HDPE welds better and easier. Go to the Drader welding web page and get information. Good Luck.

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    Member OzAK's Avatar
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    I'll stand corrected on the weldability, just takes more sophisticated techniques than I had at my disposal. There are a number of websites out there that have info. In a nutshell, best results seem to be had with: 400 degrees and 300 psi pressure on the joint with an 80% of parent material strength obtainable. Expansion/contraction rate is 3:1 over aluminum, use large head fasteners and larger than fastener shank holes to allow for this. Drader didn't have a lot of specifics on UHMW but there are others that do. One was Garland Mfg. Good luck, Oz

  6. #6

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    Quote Originally Posted by OzAK View Post
    I'll stand corrected on the weldability, just takes more sophisticated techniques than I had at my disposal. There are a number of websites out there that have info. In a nutshell, best results seem to be had with: 400 degrees and 300 psi pressure on the joint with an 80% of parent material strength obtainable. Expansion/contraction rate is 3:1 over aluminum, use large head fasteners and larger than fastener shank holes to allow for this. Drader didn't have a lot of specifics on UHMW but there are others that do. One was Garland Mfg. Good luck, Oz
    So how has the imbedded fiberglass and adhesion application been working with this sort of expansion/contraction. I suppose if you keep the boat inside during the winter it's probably not a problem but in the severe FAI cold its a cause for concern.

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    Member OzAK's Avatar
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    Quote Originally Posted by Halibutgrove View Post
    So how has the imbedded fiberglass and adhesion application been working with this sort of expansion/contraction. I suppose if you keep the boat inside during the winter it's probably not a problem but in the severe FAI cold its a cause for concern.
    HG, I took delivery of my SportJon in Jan 08, at the time unaware of at least and possibly the imbedded UHMW unavailable, don't know. The boat was ordered mostly bare bones as I wanted a project and had my own ideas and needs that I wanted in my boat. It had no paint, no mods, a bare hull with consoles, controls, no windshields bolted in, bench seat and the Sportjet. UHMW was the first step, out came the powerplant and consoles and the boat got flipped. The hull was roughed up well, as was the UHMW, cut, drilled, beveled as well, 3M 5200 applied, and then the weld-on washers. I did NOT buy weld ons commercially, I made the cutters, stamping dies and other tooling I needed myself and then cut and stamped out all those 300+ washers. Ugh! Reasons for that is I'm probably too tight for my own good but also just like making boat stuff. Anyway, the weld-ons may not be the perfect attachment method but I know for a fact that they'll take an impressive hit and not really care. Nothing exotic, they're made of .125 5052H34 aluminum welded on with 5000 series wire, penetration, as always, is the key. Thinking back the reasons I decided to use them was several fold, but the most important was decided for me by Phantom in that the way they build their boats with the box structure along the sides didn't allow access to mechanical fasteners. I see some changes in their structure from your posts but that "problem" remains if a guy wanted to install UH and not bond it on. I stored the boat inside all winter for the first couple of years, other needs dictated I move it out so it went into an unheated storage garage. So far, it has had no issues, nothing has come loose except one alongside the tunnel where the UHMW is narrow and I didn't get the penetration I needed. As for others boats, I know a lot of airboat guys that use strictly mechanical fasteners and another example is fozzy2 with his Willy Predator using all mechanicals. They all seem to hold up without many issues and very few if any spend much time in warm storage. I'm glad my weld-ons have held up as well as they have otherwise the repairs would be a real pain. Done properly, they work well. For infos sake, I used 1/2" on the keel 18' long and 3/8" everywhere else from the transom going 10' forward and 6" up the sides. For what it's worth, this stuff is used extensively in the heavy equipment industry, gets bolted on in lots of applications and is almost always attached to steel. The coefficient of expansion/contraction with steel is way worse @ 6:1. Coefficient of friction is 6 times more abrasion resistant than steel. Sure makes dragging a boat off of a gravel bar easier I can tell you. But that's another story. All for now, Oz

  8. #8

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    Find alaskachallenge on the site...........he filled a big sized gash with some adhesive last year and it held up great. I have used UHMW extensively and was impressed on wht it was able to do........sorry I don't recall the name..............YT
    Wherever you go ....there you are.

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