3.5m HDPE jetboat

yea i have the engine back in and the fuel tank all welded up, bash plate to protect the jet unit welded on, getting their slowly

 

i have all the wiring in place now, only have to lenghten the plug to the fuel tank pick up and everything else fits

 

Boy that all looks good.
I used some HDPE on my little Tin boat and it cracked. Also on my Lawn mower Hood.

I sure hope your engineering is better than mine.

 

ideally, i would like to take the boat out and have an enjoyable experience rather than a nightmare. My uncles one took some massive hits that would have sunk any alloy boats so i think i might be onto a good thing.

 

exhaust sorted kinda

 

I like your build. Im thinking of building my self a small jet boat for the rivers here in Iceland. I am a owner of a company named Ran Batasmidja ehf. We produces boats out of HDPE sheets and pipes. This material is amazing, very durable and strong. You can see our product at www.boats.is There is a video there also of our prototype. 7.2 meter long boat with 200hp motor. 40+ knots and seaworthiness and stability is amazing.
The cons of sheets plastic in stead of rotary molded boats is that it is produced under pressure. Therefore the plastic is much stronger than the rotomold boats. It can take much more impact. I have welded a big damaged in Pioneer boat after an impact with ice. 30x30 cm area where broken into pieces, something that would never happend with extruded HDPE.
Also about the "memory" of the sheets. You have to heat the material above 120° celcius. (120-140°c is perfect) to reconstruction the molicules in the material and after that treatment it has a new shape and will not try to flatten it self.

 

> Therefore the plastic is much stronger than the rotomold boats.

My understanding is that the resins typically used are somewhat stronger - say 4000 psi (extruded) vs 3,400 psi (molded). On the other hand, a roto molded boat can be made thicker in just the areas that need it. So it's not clear to me which would produce a stronger boat at a given weight.

 

Hdpe boat help

Hey Skari are you saying you heated up the hull sheets or pipe when forming it into the boat shape? How thick is your transom on a 6.5m boat with a 150-200 yamaha? . Any chance you could send me better drawings and I'll take ya fishing in Darwin, Australia.

Roto molded boats also have the downfall of a layer of poly with foam then an inside layer with no strengtheners or customization easily available.

I'm just knocking up a shed to build my first go. See how we go.

 

Why build your own poly jet unit? Jet ski unit fibreglass? Lasts longer?

 

For the same reason they make boats out of alloy, cause fiberglass is a very product choice for the application

boated shady camp and you could bounce ya way over the weirs and get to areas that have never been fished before

 

Project back on track finished my house so time to complete it I guess, my uncle is onto mk ii as well

 

Plastic sourced from Germany and the product is a far superior product than a roto molded boat, no contamination in the plastic i know exactly how thick the plastic is and where and it's a single skin boat too.

 

I am about 75% complete on a 5m v-nose punt. It has been awesome building it and just have to complete the cast decks and gunnels out of white hdpe

. I am wanting to run a jet but will probably go for a outboard jet tiller (2014 mercury four stroke 80hp jet) but will do testing with a yamaha 50hp high thrust first. Nobody uses jets here at all when everybody runs aground or tears motors off on logs.

Why would this be? some say the impellers cannot handle the silty rivers? Do all impellers have shims for adjusting tolerances? Worried my minn kota will not track straight with no outboard hanging down at the back?

Its been lots of fun and has not been too hard for this simple design. It was all plan free and hand drew the transom and went from there.

 

Windscreen on and looking good, steering boss all ready to get welded on, I'll post some pics later when I'm back in the shed

 

pictures