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Anyone tried to build a hull out of poly ?

When bottom takes a pounding from rocks ice etc adding poly solves the problem so instead of adding the weight of poly amd bolts to a glass or aluminum hull has anyone tried to build a frame of some sort like alumin t bar and angle And wrap with poly counter sink the stainless flat head screws to frame And seal joints ? Me and somebody guys were throwing this idea around just checking if it's been tried befor ?
 
Rich Andrews said:
this could get real bad... but then again some guys used flexseal
What do you mean get bad and I didn't mean flex seal or silicone to seal it must be a way to bond the poly example some sort or plastic welding or bonding agent that works for uhmw poly ? :dontknow:
 
I new of a man that had one out of poly it was fused together like when they fuse poly pipe together that they use for water pipes that are bury along roads it was all poly stringers and bulk heads deck over his complaint was on hot sunny day the poly would heat up and warp up as the poly would grow from heat but he said it was slick cant remember his last name first name was Aaron he past away about 4 years ago
 
Sorry to hear he passed . now that expansion contraction factor is comeimg back to me the stuff I was looking into was uhmw stuff it apprantly doesn't suffer from the expansion and contraction like the other polys like hdpe stuff or the other pipe if you referred to .plastec in Ottawa Ontario Sells the uhmw il check specs again tomorrow and see if they can tell me more about the expansion issues
 
Don't kid yourself into thinking that UHMW does not suffer from thermal expansion/contraction.
Most bad poly jobs are because it was not sufficiently heated. It 'grows' when it gets hot.
If not sufficiently heated (read stretched), it will 'grow' later and develop waves rather than stay straight and flat.

UHMW is just about all that is used for this application. That other stuff is for other stuff, not airboat bottoms.
Sounds like you a very intent on attaining a very expensive lesson.
 
Deano said:
Don't kid yourself into thinking that UHMW does not suffer from thermal expansion/contraction.
Most bad poly jobs are because it was not sufficiently heated. It 'grows' when it gets hot.
If not sufficiently heated (read stretched), it will 'grow' later and develop waves rather than stay straight and flat.

UHMW is just about all that is used for this application. That other stuff is for other stuff, not airboat bottoms.
Sounds like you a very intent on attaining a very expensive lesson.

Well that's why I figure I ask around on this site to save me from wasteing time and money or makeing a mistake that has been tried befor this site is awesome ! we were just thinking on some new ways to do airboats to save weight and make better power to weight ratios. thanks y'all a for the input everyone!
 
I'll second the comment on UHMW growing in heat and also from uv i suspect ,(even when it has uv additive) reason i say that is ive personally experienced it, watched it grow on a hull that i had it setting on waiting for a warm weather to come around to fasten it down and on a 43* morning the stuff in direct sunlight grew 3/4" wider in about an hour , then sun went behind the clouds and shrunk back up .... so i started marking the sides of hulls when i put poly on in normal weather to guage the streach so to speak prettymuch just out of curiosity and the black, grey ,red ... they all did it more in the straight sunlight than on a hot day and no sunlight.... you can even watch it grow and shrink on a 100* day when the sun peeks behind a cloud or two, just my uneducated unscientific findings , i thought was kinda interesting
 
Those jetboats look like some fun ...pretty scenery in thier youtube videos , did i miss it somewhere? but how thick are their hulls and i wonder how much difference or similarity is there in thermoplastic and poly?
 
Thermoplastic is a pretty broad term for any plastic that can be formed through melting and re-melting. Polyethylene (PE, "Poly") is one of many plastics that fits this bill, as does Nylon, ABS etc. UHMW PE has one the highest thermal expansion coefficient of the various plastics, but it is tough, low friction and relatively low cost. Expansion coefficient is roughly 0.00012 (in/in)/ Deg F)

A 12 foot sheet of UHMW will grow 7/8" in length with a 50 Deg. F temp rise.

Aluminum is 1/10th the expansion factor, so call that a bit over 1/16" (0.088") for the same.
Glass reinforced ABS is about 1.5 times aluminum, about 1/8".
 
I pulled this up last week, might as well post.

Here is a good resource for plastics material properties. Click on the "Technical Data Sheets" box. You will find HDPE and UHMW (Ultra-Poly) under the "Miscellaneous Materials Guide" tab. Note the friction co-efficient and thermal expansion co-efficient. If one looks through all the other material data sheets on the site, one would find that these materials have the lowest friction co-efficient, but the highest thermal expansion co-efficient.

https://aipprecision.com/resources/#guide

Poly needs to go on hot, but when it cools down it basically becomes stretched mechanically, held in place by screws or rivets and the hull. It's actually a significant load, 4-6 tons (1/4 or 3/8") in the previous 50 degree example, poly tight like a drum trying to shorten and narrow the hull. This can cause hull deformation.

If everything is built out of the same material, shrinkage issues can be limited since everything grows and shrinks together. UHMW is not a very good structural material, but the structural plastics have lower thermal expansion with higher friction. So I think it come back to a way to put UHMW onto a plastic boat bottom to get the slickest result. I imagine sliding over rocks with a jet boat is not so critical on friction factor.
 
Air canada said:
Sorry to hear he passed . now that expansion contraction factor is comeimg back to me the stuff I was looking into was uhmw stuff it apprantly doesn't suffer from the expansion and contraction like the other polys like hdpe stuff or the other pipe if you referred to .plastec in Ottawa Ontario Sells the uhmw il check specs again tomorrow and see if they can tell me more about the expansion issues



Just take a piece lay in on a board draw a line around it and leave it till about 230 then draw another. You will say holy crap. I put my poly on my hole years ago. It was warm but by the heat of the day it was bubbling up between the screws like a stuffed pillow.
 
Might be better to think of skinning a boat with poly. Building a frame, but a ultra light aluminum hull should be about the same.
 
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