I decided to risk a salt water trial, as there is no place I can think of with fresh water and a smooth beach or ramp which doesn't involve a 100 mile round trip (most beaches where I am are ocean beaches and others are soft sand/shell. The only lake I can think of is 112km away and I'm not THAT keen. Launching went ok but retrieval was another matter, not helped by an 8mph side wind (looks calm but is windy) Had a number of goes and discovered a few things which need changing, (extra front guide posts and rollers either end of the pads) The rubber resting pads stick like glue so I'll have to make some pop up rollers at the ends.

The pads hold the boat slightly above the centre rollers to avoid damage and stop it sliding off while shifting it. New front guide posts are needed as the boat only draws about 30mm and goes right over the trailer with it underwater 😮(no prop or rudder sticking out,) so it might help locate it when coming in. Jeep had truckloads of power (just fitted a new even lower geared -geared motor -1000rpm/min @ 12v), but unfortunately being only 2x2 (not 4x4) and being half the weight of the boat/trailer combo it couldn't get a grip in the mud, so needed a bit of assistance, (as did the boat getting onto the trailer). Cut out most of the vid with the boat missing the trailer about 10 times, but scored a direct hit once😊. Heaps of fun trying and heaps of washing and CRC when I got home! Going to need some new bearings at some stage, - the ones in it are rubbish and have only lasted for about a few hours running, noisy as anything now, even with gallons of oil. Stainless NMB ones next if I don't change the jet to something else, (another thought on propulsion happening)💡

Second test was slightly better, using the aluminium spiral cut universal which came with the jet unit. As you can probably hear, it was horribly out of balance (even with cable ties to reduce it). It was not even drilled centrally and the spiral is right hand when it should be left hand, (like a spring twisted against the wind, it wants to deform). Slight improvement in speed on the first test (no slip this time) but the noise was horrendous.

Have pulled the jet apart and found that the 3 blade prop is around 1 mm too small for the hole, causing cavitation (see loads of bubbles in the jet stream) which is causing loss of thrust. The prop is the wrong type as well, with rounded blades, so I have modified a larger prop with more pitch to fit snugly in the unit to hopefully increase thrust. The shaft is also wrong, with a flat cut almost half the diam and carrying on through the bearing, allowing the grease to fly out.

I actually saw a Chinese site on Al Expr stating that "some dimensions on the product may be different due to the number of machines and operators involved in its' manufacture," SERIOUSLY!!??? their quality control must be utter crap and the operators not skilled enough to eat their lunch😐 Why bother having a dimension at all?? Little wonder nothing fits properly.

Unfortunately, most model shops sell the very same stuff, unless you want to shell out muchos dolleros for European stuff. I have just ordered some 4mm silver steel to make a new shaft, so a coupling or silicone tube will fit better. Also ordered some solid connectors to try. Vibration is wasted energy so it needs to be eliminated. Hopefully the mods will improve things and allow the motor to run on 4s rater than 3s. Worked out that the motor is only 1200KV, so it's only doing around 13,000 rpm under load. Probably will need around
18,000 rpm for proper performance. Onwards and upwards (or forwards as the case may be.😁)

Sorry about the blurry vid again, but my camera lens is knackered.

Weather was perfect tonight for a test, so I did the 15km trip out to the Gulf harbour pond (most weed free pond) to throw the boat in. After a thorough under water hull inspection from the marine department, she was off. Everything worked ok except the silicone drive tube which had become enlarged due to soaking in the grease coming out the front of the jet shaft. It was slipping badly and probably losing about 60% of its' thrust. Manoeuvrability is excellent but reverse leaves a bit to be be desired. Steering in reverse is perfect but the thrust is not going forwards enough from the bucket. Might have to build in some nozzles to direct it better.

Smoke air and water are working as well as can be expected, (smoke is a bit wafty, but with too much air introduced it will disappear as it gets thinned out too much to see) I was not expecting miracles as this was a bit of an experiment (modified cheap jet unit with unknown abilities) but at least it shows promise😁. If I can find a coupling which is concentric it will solve the drive problem.

Trouble is, the Chinese insist on making a 4mm shaft, 4.95 (or whatever) which is useless for balance in a 4mm ID bearing for example. Fine for cars, but no good for boats or planes due to balance requirements (it's a mission trying to balance plane props due to this thinking,- they do it with everything) shafts for electric motors are a nightmare at times as the play they build in, can ruin an otherwise good motor. I might have to buy a flexible rubber/nylon universal or a collet style( preferable as these take up any undersize on shafts) to fix it. They included a spiral alloy one with the jet unit which is as loose as a rooster in a sock, and only good for slower things like 3D printers etc. One of these days they will learn how to machine things to fit.😐

I finally managed to get out and do a video of SY Minnow. This was taken at Cheddar Steam Club and Jane and I were the only people there so had the water to ourselves. I have increased the displacement a little which has made her more stable in the wind. Although it doesn't look it, there was quite a breeze that day and you can see the boat heeling to the wind on occasions. I was very pleased with the mist unit as this was the first time I have seen it operate properly. I will do something about the masts being out of alignment!

Hi. This is my 2nd scratch built boat since lock down began. The first was the H S L 103 finished 6/7 weeks ago. Still waiting to be tested outside of workshop. This one is built on a fibre glass hull,and has a length of 44 inches and a beam of 16. My power plant is twin out runner motors purple power. 600kv, running through twin 70 amp ESC and with 4 cell 5000 amp lipos feeding them. All accommodation is made using 6 mm three ply. And every fitting you see on the boat was scratch built by me. Lighting system is 12 v grain of wheat .props are three bladed brass 45 mm by prop shop

Surprise! 😀😂
A good laugh from 92 years ago😊
See also

😎

Taped some plastic on the hull to protect it and took it for a skid round the back yard, (you can see boredom is setting in😀). Can't wait to try it on the big sports fields (maybe bolt some wheels on it😁) and the big estuary down the road. Bit loud at the mo due to the wooden prop. More than enough power! Could do with more rudder travel and maybe a bit more area.

Super tug and steering wonder. Bought as a kit and made from wood and plastic.
There was no instructions, and without them a nightmare.eventually getting them put the basics into perspective, eventually building the boat.i changed the motor to a 480 and made my own propshaft on the lathe, also a brass rudder, which is operated by mini servo.The esc is a 10 amp m.troniks which works great small but powerful, turns in its own length to port and starboard either astern or forwards

💡Scratch built from plans. Plank on frame. Large brushless motor,150 amp esc,length is54 inches custom made propshaft ballraced at each end and middle. Has running lights,and large very bright searchlight. Flack Mats were made by better Half. Everything else was scratch built by myself.

" Elsa ", is a steam dredge barge built by Buxton Model Boat Club member Dean Ratcliffe.
She is roughly 1.24 scale, approximately 43 inches by 8 inches and is made from recycled and up cycled materials wherever possible. She has a single rudder and propeller, powered by a single motor from a drill, and two 6v lead acid batteries. She is a totally freelance design.

Found a way of pulsing the water using the pump of a dead smoker (Hen Long smoker that is) In this test I used a pump to prime the smoker pump (smoker pump on 2s) and the rest is just syphoning through the pump to the smoker. You can vary the amount of 'spitting' from the exhaust by running the pump at low voltage or maybe using a peristaltic pump with a small flow.

I did not connect the fan powered smoker unit as I ran out of silicone tube, but the result should be the same as the last vid but with 'spitting' water. Using the smoker pump for water is not perfect as it would need sealing properly, and it's cumbersome, but you will get the idea. I have ordered a couple of small air pumps, so might have another crack when they come. I'll use them at the exhaust to disrupt the water flow if they are powerful enough, rather than use the smoker pump.

Made this in about 6 weeks for my son who was not interested so I now use it for general on water filming etc. It was scratch built from a few photos and is all balsa construction, sealed and painted. Powered by a single 12v 380 motor with a 28mm 3 blade prop. Runs flat out at around 15,000 rpm.