3.5m HDPE jetboat

Is your intake grill also using some kind of screen as well?

 

my mate thought it would be a good idea to do some testing on my boat, this is the results lol

http://www.youtube.com/watch?v=3p_a7spY1o8

 

more shits and giggles, its amazing what seems like a good idea drunk and when you look at it sober not so good, all is well that ends well thou, no dent and the boat is still straight lol

http://www.youtube.com/watch?v=nnqebXGgkTU&feature=youtu.be

 

yea, helps stop stones and other foreign objects going thru the unit and damaging the impeller and unit

 

I was going to offer up the suggestion of using a hovercraft until I saw the size of the slot the jet boat went though at the 2-minute mark.

Wow, looks like fun and a bit dangerous too.

A hovercraft hull could be made using maybe 1/4 the thickness/weight, I like this construction method from what I see so far.

 

sea trials http://www.youtube.com/watch?feature=player_embedded&v=hdzacFA96NY

 

1/4 the thickness would be 1.5mm sides and 3.75mm floor, maybe a bit lightly built

 

trip report for my uncles boat, no video because the camera got lost over board


Muddy had come over for the weekend, to show me what the boat could do, He had spend the last 2 weeks on the West Coast trialing the boat. Saturday was pretty crappy and by Sunday 21st April Sunday Muddy was getting cabin fever so we went for a drive around the possible creeks and ditches on offer but in Muddys opinion they did not give the boat much of a challenge. Muddy and I noticed the Ashley river was in bit of a fresh, keen to try out the plastic boat we made a bee line home to grab the boat and head back up the river. The pelting rain and cold was no deterrent when there is boating to be done! Feeling a little nervous knowing the ashley river is renouned for pulverizing boats and sinking them i asked muddy if he was a bit worried and he replied " we'll take it as it comes".

When we got to the Ashley gorge camping ground we tracked down the holiday park owners and told them our intentions, they told us their was about 50 kayaks on the river today so be careful. We headed down the river and found ourselves talking to a few of the kayaker's there were only 6 left on the river to avoid.

We launched the boat near the bridge and with a small push into deeper water we were off. This was the first time i had been in Muddy's boat, he gave me a quick run down of how it handles and we set off. The water was brown and rather turbulant with the river running at 26 cubic meters per second, the river started off with a few rapids, at first i was bracing myself for the impact slamming the waves but i soon realized that the boat absorbs the impact very well and i was about to get a taste of things to come.

Now the first hit we had.... i only saw the rock at the last second and thought "bugger we are going to hole the boat"! The rock was about 500mm long and rose to a point, much like an axe, then BANG! I quickly looked around to see if the boat was filling with water and much to my relief and surprised it wasn't. Unusually for me i started to think that maybe this wasn't such a good idea after all, and in slight fear for my life thought about my wife and child at home. With Muddys stealth like demenor and confidence in his boat i was put at ease.

We continued up river and meet the remaining kayaker's coming down river. We held up in the current while they passed. After a few small rapids and rocks we came up to a wall of water flowing about 1 meter high. Holding in the current we came up with a plan of attack on how best to conquer the rapid ahead, decision was made, full noise and to the left. Holding on for dear life we speed up the wall of water. There was very little cavitation and with the wooldridge/Muddy design it was conquered with relative ease.

We got to where Goat had previously boated to and turned around some years earlier, with less water in an alloy boat, wise move i think (check out his u tube clips) . After a bit more discussion as how to tackle the next major rapid, we went full noise and around the rock, another success. Continuing on up the rapids got a little smaller and the valley started to open up, i was starting to think, bloody hell we have made it, a few more corners and we were through.

There were three other kayaka's at the middle bridge, we pulled over for a talk. First thing they said was "where the hell did you guys come from"! Evidently they dont see many jet boats up this far. They had lots of questions and they took lots of photos of the boat, they told us that the river is a little easier boating from here on up and the scenery it a bit better so we carried on, it was my turn to drive, not the place to learn how to drive this unique boat but away we went.

It was about another 10km up the river i was starting to get the hang of the boat. The day was getting late so we turned around about 500m before the Lees valley bridge. I had noticed a small side stream on the way up and it was time to play, turned the boat down a tight shute, rubbed over a few rocks and a quick squirt over the small rapid, airborne for the first time of many that day. Still learning and feeling a little uneasy about the handling of the boat we started to enter the main gorge. Feeling the cold i decided to put on some water proof pants. I had the boat facing upriver, when i went to turn around and head back down the river the boat didn't turn, more power you would think, right? Well no we hit the bank at full speed dislodging Muddy from his seat knocking the camera off its mount! The last time i remember seeing it it was sailing past the bow into the muddy water, i was more upset about loosing the footage than the camera. After a fruitless look we carried on down river.


Hitting the rock cliff had knocked my confidence somewhat i said to Muddy, "your turn mate, its too much for me" .approaching many of the falls on the way down all that could be seen was a line of broken water at the top, we weren't able to see what lay in the rapids on front of us, no time to plan ahead, just wing it with what we could see just ahead thru the spray of water coming off the bow. only the cliff falling away into the gorge below was a known next rapid was a monster, power on and hold on tight, we launched ourselves off the rapid that would have been over a meter high and then BANG, CRASH, THUD we landed on a rock. By this stage i had full confidence in the boat and knew it was going to hold up to anything we could throw at us. With the rapids getting bigger and waves against the rock about shoulder height i knew Muddy was onto a good thing with his design, even thou the bow went under on two occasions their was very little water in the boat.

The most scary moment was yet to come... three huge boulders. The safe side to boat is the true right, well just to mix things up a bit we went thru the middle, heading down at great pace the reverse bucket was used extensively to hold the boat in the current for a split second, while Muddy flung the bow around to the left, another quick squirt of reverse and the boat was spun around to the right. Having boulders the size of a bus and 26 cms of water going past a gap wider than your average driveway it really gets the water raging and airated, bloody scary but Muddy was unfazed and we were back down the river again.

As the gorge opened up and i got my first glimps of the gorge bridge, it was like a huge weight was removed from my shoulders, we were safe and sound and had a memory that few would believe.

 

And remember, this is what you do for fun.

Hovercraft are a different animal, some of the small ones use bare unglassed rigid insulation for the bottom of the hull. I've seen one split under the engine, he just kept on flying it around. Toughest part was getting it back on the trailer as we lifted it and the hull bent down. No real load on the hull, less pressure than a man walking on a golf course green in fact.

 

I ran across another HDPE jet boat:

http://www.mokai.com/products.html

 

grill sorted

 

It's all very impressive. I wonder if the intake grate could be made of HDPE and be more a part of the hull.

 

too much flex and the stones would pass the grill and start to destroy the impellers and stator

 

That is definitely a good set of impact tests!

Congratulations to your uncle.

 

tank sorted just gotta weld it up now, works out about 100 Liters