Sun was out, wind was down, so took the boat for swimming lessons. Went very well, no problems other than the silicone couplings trying to screw themselves off as usual, (too much bite and torque) and bunching up to the motor causing friction), (have a possible fix I'm working on for that today) Heaps of power from the 2 - 540 HV brushed motors only running on 3s. Never went much more than a tad past 1/2 throttle which was spot on scale wise.

Very quiet as well, - mind you, couldn't hear much anyhow with a road milling machine working at the end of the pond about 150m away, at around 80db where I was!!😠😠😠😭 Of course it would have to be there today,! something like this always stuffs my plans up, cars, trucks, screeching seagulls, people talking to you while you are trying to make a nice quiet video etc etc. Can't seem to get away from noise. Added to that, the video's crap,- as soon as it uploads to YT it turns to rubbish,- was quite acceptable till then.

Must be the wide format they use, as it's fine in a small screen (ie YT preview) and my computer. Worst thing is, it took an hour to load this rubbish on a fibre connection!! Not loading any more till I get a better camera, "Santa, did you hear that ?"😁

I might de-power it a bit, as it has too much power really,- might put 2 540 45T motors in which will run on 2s nicely with 30mm props (has 35s at the moment) and not be as touchy on the throttle. You can steer this just using the throttles it's so bitey. Spins on the spot like a jet boat as well. Stereo worked well, but the IR remote doesn't like working too far away in bright sunlight, (have a separate vid, but YT would give a copyright warning, so I won't put that up) The vid is garbage, but you'll get the idea😁

Finally had a chance to do a test on Pilot 40 project that was my lockdown stay home project . Change the props to 50 mill.4mill.threaded & now I have right prop & left prop Replaced the Sabertooth speed control as it was to hard to control with my Airtronics transmitter used a standard Hobby King speed control changed the wiring terminal block to a larger size as the one I first used was to hard to put wires in it . I always have trouble with mounting so glued the motors in with some goop & there just fine now

Fitted the new 550 45T brushed motor as a replacement for the ancient and slow 70s Graupner monoperm. Goes a lot better now and has a decent speed range. Handles and rides quite well for a skinny boat. Prop is a Graupner 40mm 2 blade (don't know the pitch, -fairly fine) Using a 2200mAh 2S LiPo battery which probably gives around an hours running slowly, or 30 mins of hooning around.

Battery was only charged to 8.25v and ended up at 7.7v. (45%) after about 3/4 hr. I'll probably fit a Hobbywing ESC as well, for a bit better reverse action, as the El cheapo car one is a bit slow finding reverse at times.

Typical yorkshire weather, after 5 minutes it chucked it down so had to make a quick retreat. used just one 2200 3s lipo for now but need a bigger lake/pond really as can only give full power for 3-4 seconds, so stop -go is not good but was hoping to get some good photos-videos, but the rain stopped play till another day.
Edit, forgot to mention. most of run on centre prop only. the last 5 seconds or so is full power, well nearly.

I've replaced the old 6v sealed wet battery with a lipo 3s,11.1 volt 2200mhz, 100c spectrum smart battery. so the 1st run was cautious i just fired up the centre prop to see how she performed, well i was surprised at the turn of speed she had on just 1 prop, and how well she planed, it was a little awkward filming and controlling the boat by myself as i was the only one pond side. this was not without mishaps though, see 2nd video
After checking the boat over she was found to be unmarked and no bits missing, not bad to say she hit the pontoon at full speed, took off and plunged back in at the other side.
So the second run i started on the centre prop and then opened her up on the outer 2, she shot forward and immediately stalled, dead in the water. luckily i could reach her with the ponds barge pole to pull her to the side. i found the fuse had blown , i had fitted a 20amp mini flat fuse, i didn't have a 30amp only another 20amp which blew just as quick, upon opening up the outer props.
any ideas anyone or will a 30amp do the job, or a 2s battery? help any suggestions considered.
Roger

Part 1. ideal conditions; nearly 30°C, cool Bier at hand😜
Sea Scout built by Dad in the early sixties with a Taycol Target and 6V lead acid wet cells (very wet😡). Renovated and dragged into the 21st century over the last several months 😉
See Build Blog 'Sea Scout 'Jessica'' for details!
Motor: Propdrive 2830, 1000kV, 30mm 3 blade Raboesch prop. Quicrun 16BL30 (30A) ESC with BEC.
Tested with 3 battery types, all started with 99% measured capacity-
1. NiMh 4.2Ah 7.2V, nom. 408gm.
Result: Speed sedate (OK 😉scale river cruising!) No planing.
Max current: 3.6A
End status V / capacity left: At end of short run ca 3 mins. 7.78V 99%.
2. 2S LiPo 4.0Ah 7.4V nom. 257gm.
Result: Speed still sedate but due to lower batt weight at least the forefoot came out of the wet stuff! Max current: 4.1A
End status V / capacity left: At end of short run ca 3 mins. 8.25V 93%.
3. 3S LiPo 4.0Ah 11.1V nom. 315gm.
Result: Now we're getting somewhere!!😁
Good speed, manoeuvrability and planing 😊 Max current: 7.5A
End status: 11.95V 74% after several long runs, ca 20 mins total.
Estimated (extrapolated) endurance on a 4Ah LiPo around one hour - mostly 'full bore' - 'Pedal to the metal man' 😊

See also:

The competition!

Final run. (Beer was getting warm😁)

Cap'ns log entry:
Boat dead-weight w/o battery: 1.8kg.
Spray rails to be added!😲
Slight list to port to be trimmed.
Rudder servo to be reversed!!😲
Keel protection to be added: some scratches and flaking from stony sloping shore 🤔
Summary: much as expected👍 Forget anything less than 3S.
Anyone want to buy a batch (4) of new 2S 4Ah 45C Lipos? 'One careful owner'!
Happy boating people, Cheers Doug 😎
PS Many thanks to Camera girl Gisela 👍
Recorded in 1080p HD.

well finally got there. she sits a little low in the water, but evenly along the water line. this was with the battery central to the hull. when powered up the centre screw alone moved her quite serenely and was very manoeuvrable. when power was added to the outer screws I would say she didn't plane well as she wasn't going fast enough. even with all props on full power, I think also she is to heavy and the battery too far forward.
So to remedy this I moved the battery back a compartment, positioning it over the 3 motors , it was a tight squeeze, but fitted just.
This sat the stern down a little and the bow up and gave the impression of planeing, she still not fast enough though. the scale speed still doesn't look right.
I'm going to have to have a rethink on this one. having said all this though she looked well in the water if i say so my self.
Roger

Set the new Surpass 3000KV 36 diam finned in-runner up in the boat, and did a tank test. Lots more power than the HV brushed 1200kv 550, but with higher idle. Re-did the reinforced silicone coupling and fitted a small collar to the inner end of the motor shaft to hold the tube from moving forward against the motor, as with the extra torque of the in-runner, it was trying to twist the tube off the shafts. Seems to be hanging in there static which is a promising sign. Once running, the load will come off which should help.

Runs full at around 4A and the battery holds at around 3.8v/ cell )alarm is set at 3.6 for safety, (as a sort of rev limiter) performance should improve a bit now. Have to wait till tomorrow as the restrictions end at 6am Sunday, (then have to hope for good weather for the test) The prop in the jet is a 28mm 3 blade racing prop which I modified to fit. Don't think I'm going to get much more out of the jet unit without it exploding😁, (it's only plastic I think, not GRP), - might have to buy a back-up and fit it with better quality bearings etc. If the jet was in the usual 'plastic' 24" toys it would be a rocket, but it's pushing 6lbs which is a challenge😀

Note the police chase outside in the background😁- always action around here, lots of hoons in cars😁

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!