Recycled Plastic/Plastic Lumber Hulls for Pleasure Boats?

[Keith King]

Exhalted Members of the Forum,
I had that head injury so humor me if you will. Bales of High Density Polyethelene (HDPE) (Milk Jugs) sell for about $400 U.S. per ton in my area. Experiments I've done at home have shown that shredded H.D.P.E. with a 40% filler of sawdust or shredded paper mixed in can be molded or extruded to the desired shape with heat and pressure. It's no secret. This is the way "plastic lumber" is made. Is there anyone out there with some thoughts on how this material could be used in boat construction? I'm dreaming of under water flight with my new engine concept. I don't think fiberglass is optimal for that application.

Thanks

Keith

[Brett Salter]

Keith,

Kayaks made out of HDPE have been around for years. Recently, a Boulder, CO company has set the drift boat world on its collective chine by making a really beautiful and functional boat. It is lighter, quieter, lower maintenance, and much more rock-proof than wood, fiberglas or aluminum (no I don't work for them). Check out the website at www.boulderboatworks.com. They apparently use a marine-grade HDPE that is UV resistant. I found one link to a San Diego company that sells the stuff in sheet form (the drift boat uses .250" sheet material). That link is www.sdplastics.com/marine_board.html.

I'm intrigued with the idea of using this material to make a flat bottomed fishing boat designed for our rocky and shoaly eastern streams -- a glorified/beautified jon boat if you will.

Brett

I had an idea similar to this a few years back... though slightly different.

My idea was to create an HDPE kayak by first making convex molds
out of earth for its top and bottom halves, then pouring molten HDPE
over and smoothing out the goo.... Never did get around to trying it,
though.

[Keith King]

Hello Mr. Brett,

I started messing around with melted milk jugs (H.D.P.E.) and sawdust filler about 5 years ago. The possiblities are endless. At the time, I had never heard of plastic lumber. My wife came home one day and I had a bread pan full of chopped up milk jugs in the oven. The noxious fumes and smoke were just getting thick when she showed up. Boy was I in trouble! I continued my experiment anyway. You have to melt that stuff in an air tight container. The other response from Nonymous talked about pouring melted HDPE. It melts to a sticky bread dough consistancy at about 300 degrees. I then mix in about 5o percent sawdust (by volume) It cools and thickens quickly so you have to work fast. For a flat bottom skiff, make sure the positive mold will come apart. The plastic shrinks as it cools. A concrete mold would probably work well using heated sheets of HDPE. Last time I checked, HDPE was about $400 a ton delivered, add 1/2 ton of sawdust and you've got a very cheap, strong building material. The sawdust filler also serves as a physical barrier to protect against U.V. degradation and theres no waste . It can be remelted and made into a new product.

Think about it!!
Keith

Originally Posted by Brett Salter

Keith,

Kayaks made out of HDPE have been around for years. Recently, a Boulder, CO company has set the drift boat world on its collective chine by making a really beautiful and functional boat. It is lighter, quieter, lower maintenance, and much more rock-proof than wood, fiberglas or aluminum (no I don't work for them). Check out the website at www.boulderboatworks.com. They apparently use a marine-grade HDPE that is UV resistant. I found one link to a San Diego company that sells the stuff in sheet form (the drift boat uses .250" sheet material). That link is www.sdplastics.com/marine_board.html.

I'm intrigued with the idea of using this material to make a flat bottomed fishing boat designed for our rocky and shoaly eastern streams -- a glorified/beautified jon boat if you will.

Brett

[FAST FRED]

The canoes at Old Town are made in an interesting method with plastic.

A Monel mold has 3 air operated hopper boxes inside .

When the mold (mounted on a modified truck rear axle to tip & roll) reaches temp in an open oven , the first box of plastic is opened , and the outer canoe skin formes as its being sloshed about the mould.

Second layer "the structural" is done , and then the final inner visable skin is released.

Takes about 10 min , the identical mold "other" side of the truck rear end is cooling , the now finished hull is unloaded and pre measured bags of new plastic are loaded in the hoppers.

The Monel mold IS expensive , but the CFO revealed that the entire canoe is made & finished with unde 2.5 hours of labor.

Want to do a LOT of unbreakable plastic boats?

FAST FRED

[Keith King]

Fast Fred,
Greetings from the Big Easy. That sounds kinda like blow molding. Where a tude is extruded into the mold and air pressure is used to press the tube into a balloon that fills all the nooks and crannies of the mold. There's a lot of the material out there and it's cheap. You just need a big heated play dough factory and a sellection of dies. What I like is that parts or sections can be molded in one piece. My interest lies in a postitive bouyancy craft that can make short underwater flights, function as a traditional boat and possibly take advantage of ground effect flight. I know it sounds like a pipe dream but I have this new engine design that should produce a lot of new line of craft. My Alpha Jet (A.J) is a linear engine with no moving parts. It's a cross between a pulse jet, a machine gun and an internal combustion engine. It can also be used as a steam generator. It works for squid, octopus and other jet setters of the sea. I want to copy that action mechanically then put it on amphedamines. I'll also need an air ride suspension system to power my passive "super charger" A boat with a suspension system! Ain't it about time!! Anyway, I still have to build a proto type and work out the bugs. As for as the plastic lumber stuff. I think it could be the building material of the future. Besides boats, I'd like to see it used as a semi submerged artificial reef which is also a human habitat. Using a concrete outer layer with nooks and crannies for sea life the "Keep" as I call the place, would only get stronger with time as coral colonized the structure. There's solar, wind and wave so the place should produce an excess of electrical power. Sea life is attracted to cover so supper would just be swimming around.

I'm sorry to ramble on, I had this head injury. I may be a crazy cripple but I still have my dreams!! When are we going to find a way to harvest all the "Methane Hydrate" in the oceans-it would be a lot cleaner than oil and there's an enormous reserve. It sure would work well for my engine too!!

Later

Keith

Originally Posted by FAST FRED

The canoes at Old Town are made in an interesting method with plastic.

A Monel mold has 3 air operated hopper boxes inside .

When the mold (mounted on a modified truck rear axle to tip & roll) reaches temp in an open oven , the first box of plastic is opened , and the outer canoe skin formes as its being sloshed about the mould.

Second layer "the structural" is done , and then the final inner visable skin is released.

Takes about 10 min , the identical mold "other" side of the truck rear end is cooling , the now finished hull is unloaded and pre measured bags of new plastic are loaded in the hoppers.

The Monel mold IS expensive , but the CFO revealed that the entire canoe is made & finished with unde 2.5 hours of labor.

Want to do a LOT of unbreakable plastic boats?

FAST FRED

i was reading the posts about using the plastic polymer for boats and am wondering if you could make a mold to make the outer layer of a surfboard with the plastic? if so how much would this cost? i am working on a project for a new surfboard material and need any help i can get....thanks

[Keith King]

Hey surferjoe,
Fast Fred described a homemade canoe mold. Talk to the guy. Perhaps you can get him to help make the mold and handle production. It's probably going to be stronger but heavier!!

Good Luck,

Keith

Originally Posted by surferjoe

i was reading the posts about using the plastic polymer for boats and am wondering if you could make a mold to make the outer layer of a surfboard with the plastic? if so how much would this cost? i am working on a project for a new surfboard material and need any help i can get....thanks

interesting stuff. i'm a blend operator for a company that manufactures vinyl siding and composite decking. the first word i would ban from any discussion of composite wood is, "sawdust." sawdust is the stuff for dust collectors because it is exactly as represented, dust. my replacement word would be, "woodflour." woodflour is made from wood much like regular flour is made from grain. a sieve test shakes the flour through a series of screens, starting with coarse and ending with fine mesh. anything that makes it through the fine screen is dust. a company that was supplying woodflour with consistant 12 - 20 percent dust has been replaced by one who holds the dust content down to 5 percent or less. anyway, milkjugs are ok, our competitors use them. the main weakness of compsosite lumber is just that, weakness. lacking the fiber of natural wood, composite wood has no tinsel strength or load bearing capacity. (eg. you can't use composite 2 x 4's for wall studs or composite 4 x 4's for deck posts other than railing posts.) the other drawback for using composite wood in marine or other mobile applications would be weight. it's probably about twice as heavy as wood. that being said, composite wood is still intrigueing because it won't rot and it's a dream to work with. it is entirely nail, screw, saw and glue friendly. no surprises. i'm planning to use 1 x 4 composite for stringer replacement in a 16 ft. seaking (starcraft) i inherited from my son-in-law. this being a first-time, low-risk project (the craft has a history of changing ownership with no money involved,) i'm very comfortable at the bottom of the learning curve. thanks for your forums. dave