Hi Eric.

Looking good.
I would be interested to see more photos of this Lifeboat and its crew.

Martin555.

Hi the Graupner yachts are the best, I have a Gracia and she sails very nicely and such a pleasure to watch. She had a small change last year to the servos and works for ever on a 4 AA cell pack 2300mAh. I have a little less sail area and have a sail servo the same size as a standard servo and this copes OK.
regards Roy

JB,

Looks like a perfect day. I find sailing very relaxing and quiet, with no engine/motor noise. Can be quite challenging though, especially when you need to bring it back in to the dock.

Graham93

Hi Martin, Nice and quiet and very relaxing, and with a decent battery you could run all day for free (almost) - the less you move anything (winch/rudder) the longer you can sail. You could go the length of the pond in the right wind with just a touch of rudder now and then. No shafts etc to worry about.

JB

Hi Jb,

Did you find that more relaxing than an electrically power boat or just the same.?

Martin555.

This is an excellent Video.
I can't get Eze Kote is SA but, I can get Z Poxy products.😊

That's a good, handy video.
Thank you for sharing it.

Will

T'ink dat cool Phil.
Liking dat man.

Congrats Rasta Lieutenant.

Martin555.

I might have guessed he couldn't resist a reply😂

JB

That Martin is a very naughty boy.
I know on his School reports it said this boy is easily lead and is disruptive in class.

Martin555.

Hi Graham, you can blame Martin for this, - he started it, - the little voice on your shoulder, saying "go on, you can do it" , - bet he was a trouble maker at school😂😂 Glad we can have fun and a bit of chain yanking. (LOL)

JB

Thanks for the offer Doug:

“If you're interested Graham I have such an 'Orange' receiver going spare cos it's not compatible with my Spektrum DX TX.😭 I'd trade it for any old surplus Arduino board you may have “

A few problems though:
1. It also isn’t compatible with my FlySky TX 👎
2. I’ve never used Arduino, and don’t have any surplus boards 👎
3. Most important of all: I’m trying not to get distracted from my current build. There are just too many interesting challenges out there. I’d never get anything finished if I tried them all 🙄 Doesn’t mean I can’t think about how to solve them though..🤔

Seriously, thank you for the generous offer, but no thanks..

Graham93

Hi Doug, I know it's a bit hard for people to get their heads around how a waterjet works (not accusing anyone of being senile😂), as it is totally different to a prop drive (and something people don't even think about). I'm trying to think of a good analogy to describe how it works. Perhaps if you think of a jet engine using compressed air for forward thrust, then convert the air for water. It's mostly just the sheer force of the water being pumped that drives the boat forward.

Re- on or under water while planing,- I've taken a screen shot from Hamilton jets site which shows quite nicely what I was describing. While they work well underwater at slow speeds, you can see the jets (arrowed) completely clear of the water and only hitting it way back at the wake intersection (where bottom and side displaced water rise up and meet), making the characteristic jet rooster tail. (I'm sure you will like this supplementary PDF😁)

http://depts.washington.edu/uwefm/wordpress/wp-content/uploa...

I've included the Hamilton site (with the vid) for your perusal😊 Re the nozzle I've fitted,- the original 'splatter' nozzle is on the left and the new reduced close fitting one on the right. Another analogy😁 for this is,- imagine blowing out while keeping your mouth open, then do it with your lips pursed,- the latter is more concentrated. Clear as mud?- you will be in the next episode of....................😂

https://www.hamiltonjet.com/global

JB

http://depts.washington.edu/uwefm/wordpress/wp-content/uploads/2017/10/manuscript.pdf

🔗

https://www.hamiltonjet.com/global

🔗

Just bought 1 ea of these to try Doug, only prob will be delivery time😴 Will look at Krick as well to cover the bases maybe.

JB

RE -Could try a pin and bush coupling. Standard practice in full size engineering as it transmits shock loads and could well be small enough to fit.

Hi Ian, unfortunately don't have a lathe, otherwise I could solve a lot of model problems, (maybe Santa will bring me one?- yeah right!) I have a large mill which is very useful at times but no use for this stuff. The old ball/pin and dog system which I used on my IC boats is great but can't find any the right size. This is something which as you say, probably needs custom making.

JB

Re, - You were dead right BTW, the red coupling in my Sea Scout was also from Krick

Thanks for the info Doug, - very hard to find precision fittings any more, especially in a small size. Will have a look at the Krick stuff as I know it will be good. I thought of the old drive dog system which I used on all my nitro boats but I can't find a small enough one to fit . They take up any small mis-alignment and can run quite quietly when set up correctly, (also the strongest, long lasting coupling by a long shot, (still have some 42yr old ones which had had a thrashing behind an OS .45 RSR (rotary rear disc intake) for years which are still in perfect cond.

Problem is, there is just not the selection today that there was back in the 70s and 80s with the loss of Graupner etc (old quality Graupner that is) and when boat racing was a big thing (especially in the states) Same with planes, with big money international pattern competitions etc going on ( big names like Wolfgang Matt, Bob Violet etc) . Haven't heard of any like that for years.

I'll be waiting till next year if I order anything now as being down the butt of the world has its disadvantages round Xmas, (my coupling orders from Ali Exp apparently are going to take 10 days just to be shipped by the seller, let alone the rest of the crap, - read Feb next year if I'm lucky. Did try the new shaft and prop which was looking really promising till the shaft moved back and the prop hit the flow correcting vanes in the outlet, (lots of noise but no damage.) Not much room for a shaft collet so may have to cut a circlip groove to stop it.

At least I'm lucky enough to have big boats to play with while I'm waiting. Better get the rods out and dust them off.😁

JB

This Krick coupling is almost a gear type coupling and very good at transmitting high torque from the start up. But alignment is sensitive

Could try a pin and bush coupling. Standard practice in full size engineering as it transmits shock loads and could well be small enough to fit. Easy to make if you have a small lathe.
My memory of equipment built 40 years ago was the prop as such is a almost a 4-5 bladed turbine rotor that will just fit in the tube. As pointed out to stop cavitation.

Hi again JB,
Thanks for that vid, that looks very effective.
What immediately struck me was the nozzle shape, just like the fire hose that you mentioned in your analogy.
Can't remember what nozzle shape you used but I wondered if such a shape, maybe angled slightly down, might help improve the effective thrust?
I appreciate what you wrote about 'the force of the water' etc, Newton's 3rd Law an' all that, + mass x acceleration etc. BUT, surely there is a secondary reaction between the incompressible water jet and either compressible air or more incompressible water.
I hear what you say about various boats whose water jets are partially above the surface - but at what cost in extra power input?
In your backpack water jet rider remember he is riding on that column of incompressible water.
As soon as he goes too high and the column loses direct contact with the surface then ... SPLOSH!
From what I have seen of jet skis the jet outlet is always under the surface. Planing should surely just push it deeper if the initial static balance of the vessel is right.
Just my 'thonks' but wadda I know😉
Keep on jetting Man👍 Guiness Book of Records look out ... JB's a comin'!!
Cheers, Doug 😎

Hi JB,
" this unit has the very coupling I mentioned (red). It is 3 parts and has a captive rubber cross in the centre. They look like a very nice coupling."
Indeed, and very reminiscent of these I just bought from Krick, to try out on the two outboard brushless on my PTB refit.
https://www.krickshop.de/Accessories-Spare-Parts/Accessories...

You were dead right BTW, the red coupling in my Sea Scout was also from Krick👍
This one is exactly the size you need-
https://www.krickshop.de/Accessories-Spare-Parts/Accessories...
It's not actually a spiral, more succession of offset slots with a solid core. I have tried spirals and springs in the past and they all failed. Wound up and snapped or unwound and tangled under load.
Ever tried buying a matched pair of LH and RH wound springs? Not easy🤔

Anyway the red job handles the 1000kv brushless, running on a 3S, into a 35mm prop at full load in my Sea Scout as long I want without a whimper. And it's absolutely SILENT🙉😊
Another nice thing about the red job is that you can order it with a variety of inserts to match all the usual motor / shaft combinations, no shims needed. The inserts are also available separately.😊
Best is; when Krick say they are in stock (Auf Lager) and can deliver pronto - they are and they do!
Prob about two weeks to you by Kiwi Post.😁 (No Sampans😂🤣)
Hope this provokes the odd thought or two (what else but odd from us experimenters?😁)
Cheers, Doug 😎

https://www.krickshop.de/Accessories-Spare-Parts/Accessories-for-Ship-Models/Shafts-Couplings/Power-Heavy-Duty-Clutch-5-4-mm.htm?shop=krick_e&SessionId=&a=article&ProdNr=ro1446&p=192

🔗

https://www.krickshop.de/Accessories-Spare-Parts/Accessories-for-Ship-Models/Shafts-Couplings/Stegkupplung-kpl-3-17-auf-4mm.htm?shop=krick_e&SessionId=&a=article&ProdNr=63902&p=192

🔗

This time I DEFINITELY do NOT want to know where the water would enter and exit poor ol' Jim!!😮😭

JB My first thought was also gyro gyro gyro!
Maybe coupled with or instead an RX with built in stabiliser function?
Intended to assist flying in windy weather.
Could help to reduce the programming task Graham.
If you're interested Graham I have such an 'Orange' receiver going spare cos it's not compatible with my Spektrum DX TX.😭 I'd trade it for any old surplus Arduino board you may have 😉
Cheers, Doug 😎

You could use a quad copter gyro to steady him Graham, and a high pressure water pump run out the back of a fake jet ski (most are run off jet ski attachments) for realism?😁 oops- sorry didn't mean to give you ideas😂 You could do it like they have at a waterpark display here, where a clear water tube is hidden by the falling water from the object (can't remember what it was,- dolphin I think), making it look suspended on a water jet.😁

JB

LOOKOUT COUSIN JIM LOL!!!!

Martin555.

JB, Martin,

I do like a challenge, but I think that might be a step too far.😔 There are low cost 3 axis accelerometer chips that would enable the measurement of orientation that would be needed, but using the data from them to control the jets, and making it all waterproof ...

There again, I do have Bionic Bill’s cousin, Jim, sat in the workshop with nothing to do....🤔

Graham93

The video 'Awesome Water Jetpack' could this be a future project.

Cut it out Martin, you can't tempt me that easily, but Graham likes a challenge😂 Controlling it would be interesting😁!
JB

Just found these on Ali Expr, (made by TFL who make jet units) and bought one to try. Only problem is they are only in d4 x d4 so I'll have to look for a 4mm shaft motor or shim this one (jet's 4mm and motor's 3.16.)

Just found this vid Doug, and this unit has the very coupling I mentioned (red). It is 3 parts and has a captive rubber cross in the centre. They look like a very nice coupling.

Water Jet Thruster For DIY RC Boat

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Hi Jb,
The video 'Awesome Water Jetpack' could this be a future project.

I can just picture it 'Action man' or a friend of Graham's Bionic Bill flying about that will be a crowd puller.

Just another little seed planted.LOL!!

Martin555.

Re -Hi JB and Doug You might be on the right track. A club member has the Graupner Atlantic Challenger the azimuths sit literally in the water.

Hi Ian, good thought, but as mentioned to Doug, the jet nozzle is only in the water at rest,- once the boat is planing the nozzle is out of the water and it's mostly the water jet thrust doing the pushing work. See vid in my reply to Martin. A similar effect can be seen on those water jet packs which are working in air.

JB

Awesome Water Jetpack - Compilation 2015

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Re,- Can it be that the water jet is too high in the hull?

Shouldn't be Doug, it can't go anywhere else as it's a fixed unit. The nozzle is pretty much under water at rest and it picks up water immediately which shows it's ok for position. Jet nozzles don't need to be under water (once planing they are out of the water anyhow) as its the force of the water jet which gives the thrust, (think fire hose) Problem is as mentioned that it's just a crappy unit which needs a few tweaks to improve it. I've fitted a high pitch racing prop and filed it down to fit with about .2mm clearance which is way better than it was. The new shaft I'll be making will help centre any coupling (if it's reamed, not drilled to the correct ID) Problem with Chinese stuff is that it appears mostly just drilled to a final size (which is usually a 'nothing size') and invariably sloppy.

I have a tray full of prop drives for planes and they are all different and some are so bad as to be unusable,- 1 in 5 might be a decent fit☹️. The only reasonable ones are either collet types or bolt on, and even they can be a pain to balance. I like the look of your krick? red connector and I have seen some 2 piece connectors with rubber inserts which would be ideal,- but finding any with the correct hole sizes is the biggest problem. Anything spinning really fast (ie 20,000 rpm, needs to be pretty much perfect.

The aluminium spiral one I have has both grub screws on the same side, thereby making it useless for high speed (plus as mentioned the wind is the wrong direction) Motor itself is perfectly balanced and is a ball bearing, brushed 1200kv 12-24v so that's no problem. Jet unit has 2 bearings on the impeller shaft and spins smoothly with no play (unusual) and the motor is mounted to an aluminium plate which is part of the jet unit, (bolts onto the foot) and is surprisingly accurate. I have ordered some solid joints to line it all up perfectly (as you have mentioned) and am having an intensive search for a compact rubber insert joint (can't be longer than 20mm) to remove any fine vibration problems.

Not sure how strong the red connectors are (this motor might tear them) but they might be a solution, (need to be LH wind and have a 3.16mm-4mm option) Pic is of correct impeller types, (they are not like an ordinary propeller, being a constant diam) -may need to lash out on a 26mm one😮, (not cheap!) Pick-up grille might be another problem as the slats are horizontal not vertical, which might also cause cavitation. Might have to make a brass one if all else fails. Every little bit will help😁 (Top prop in pic is the modded one)

JB

Have fun with your experiments Jb.

Martin555.

Re -I have a feeling that this could end up with a prop and rudder.

Had thought about it originally Martin, but thought I'd have a go at the jet, (or a V-drive using a crawler drive splitter) as this was one of the main propulsion methods for this model Hartley. The motor is a brushed unit which can run up to 24v but is low kv, and it would be a job to get a 4s in the boat (maybe a small one). It would do better with a high kv (2000kv) inrunner on 4s as the prop is only 27mm and needs to scream to get decent thrust.

The jet is only a cheap modified one so as I mentioned, a lot of experimenting needed to get the max out of it😁. Most of the model jet boats you see really flying, are quite small and light weight with really powerful water cooled in-runners on anything up to, 6s, and with expensive one way (no reverse) jet units with aluminium or stainless impellers. I could do with another 2-3mph which would be about scale, but not interested in a pond rocket as that's not the intention (I can knock one of those up in a week). Just a matter of playing with different ideas till it comes right😁. If nothing works, then maybe ------- Here's a vid of what I'm up against, (power to weight)

JB

RCJETBOATAUSTRALIA rc jet boats with pumps. available models and water test

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And another shot!
Gives you an idea

Hi JB and Doug
You might be on the right track. A club member has the Graupner Atlantic Challenger the azimuths sit literally in the water.

https://forums.offshoreelectrics.com/showthread.php?365-Graupner-Atlantic-Challenger

🔗

Hi JBKiwi,
Another thing that robs torque is mis-alignment!

Hi JB,
Can it be that the water jet is too high in the hull?
Much of the jet seems to be dissipated above the surface, where it has no effect due to lack of resistance from air. Not easy to see clearly in these Lo Res vids🤔
Ref Prop shape; take a look at any Kort Nozzle to see the blade shape and how closely it is fitted to the nozzle. Of course to achieve the necessary close fit and good thrust there can be no vibration / misalignment in the shaft coupling which may cause the impeller blades to touch the jet tube sides.
Have you inspected the tube for any damage? Gouge marks, frayed impeller tips?
Use a rigid coupling (I whizz mine up on the mini lathe😀) to align the motor to the shaft; run the motor at low volts with an ammeter connected, twiddle the motor around until minimum current is indicated together with smooth running; max revs at min amps😀
Spot glue the motor in that position (blobs of slow setting epoxy / filler can help at that stage), disconnect the whole set up and fix the motor permanently. Replace the rigid coupling with one allowing only minimal misalignment, like the spiral one I fitted to my Sea Scout (see pic) and all should be dandy.😀
Cheers, Doug😎

Hi Jb,
I have a feeling that this could end up with a prop and rudder.
I don't understand why she is under performing.
It should be like a pond rocket with that big water jet hanging out of the back.

Martin555.

Seemed to work a whole lot better in the tank for some reason Martin. Possibly due to the coupling slipping, (the squealing is it slipping) Just a bit of silicone fuel tube. I use it on all the boats as it's quiet, self aligning, and lets go if your prop gets jammed by weed. Problem is with the jet, it has a flat on the shaft for some reason which doesn't help the tube grip, and lets grease in causing slippage. I'll sort it eventually,- didn't expect miracles first time out (same with planes) - Almost always some small initial problems.

Motor should be spinning at 15,000 rpm with a 3 cell, but performance is not matching that, obviously,- just piddling along😁 Mind you, I used to cruise like that in the full sized boat, as the Zodiac motor used to suck gas like nothing at 20 knots plus, (gallons per mile, not miles per gallon!)

JB

Hi Jb,
Nice to see her in the water.
I am very surprised at the lack of reverse.

Martin555.

PS , recently tried prop for auxilary power ! - but reverted to sail !! - Next, going to try a stern mounted deck mounted pusher !!!!!🤞
Phil

Hi Peter, nice to hear from you and that the majority of Australia and borders have re-opened and that you guys managing to get back to the lake/ pond !.

Ok on your observations, for sails I mainly use ripstop nylon, mainly for colour variety and good light/med weather. I dont usually sail in heavy weather but I do have 1 suit made from a more ridgid sail cloth which certanly holds its form better. However, I do find that ,the ripstop does absorb streatch in heavier winds thus inducing a bit of "belly". I really must get hold of some mylar to try myself.

I dont recall cutting to a triangular shape as I use a template (see photo) however I recently joined up two 2 panels with double sided tape, then did a 3 panel suit (again in ripstop) which
added a batten like rigidity.

I do enjoy trying out other materials and design options within the Wee Nip design brief, but now also getting fun from filming other members boats from the "Camera Nip".
Take care Pete - cheers and beers !
Phil

Hi Phil and well done. A great video. We are out of lockdown in the majority of Australia and borders have opened, thank goodness. A question, I have noticed that a lot of your boats do not have the traditional Wee Nip sails, in that the large pocket at the front is now a simple slip on type pocket, or fitted like the yellow boat with yellow sails with the rings etc.

I was given a few meters of a heavyweight mylar paper and have been experimenting with different sails, the current one being fitted to the mast with rings (small zip ties). I sailed it against the fleet last weekend in a swirling light breeze and it did reasonably well, especially after some tuning and in spite of the weight of the material used.

My query is that I noticed the yellow sail was cut into a triangle shape, without the rounded shape on the back. Was that a benefit? Mine seems to bend or twist in that area and not form nicely, possibly causing issues on the water. Not helped by the weight.

I will put up a couple of images that show it and see what you might think. I might be better off cutting into the triangle.
Any thoughts gratefully received.



Cheers

does look nice and peaceful,i like your name partial to a wee nip myself
brian👍