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Member postings for Dave Cooper 6

Here is a list of all the postings Dave Cooper 6 has made in our forums. Click on a thread name to jump to the thread.

Thread: Fairmile D - help needed
22/06/2020 10:56:25

Hi David

Could I suggest a few simple tests before "committing pond" :-

- Run it on the bench in your proposed configuration. If you have the electrical test kit, measure amps (and watts) at different throttle settings. Quickly touch the ESC - insulated part - and feel the temperature.

- Put the props under static load, finger on end of prop boss(es), or, simple scrap balsa wood 'snubbers'. Check ESC temp again.

- Bath test. Feel the pull at the stern with different throttle settings. Check ESC temps.

if you have to quickly withdraw your finger from the ESC in any of the above - it's running too hot ! You need to do something about it...

Battery life /power delivery etc - These days, for a high-speed launch (brushed or brushless motors), I would only really consider LiPo's, although NiMh's (or, equivalent) may also be ok. One way or another, you need to establish your battery life before going on the water. Most modern Tx's have a timer facility - set it to a conservative amount initially.

In short - test, test, test...good luck,

Dave C

16/06/2020 10:44:02

David, my Dad was a skipper on 70' recue launches in the war. They mainly used the two 'outer' throttles for manoeuvring in harbour (3 shaft boat). I imagine at speed it would just be helm steering...

For the cooling on my boat I made some air extraction vents. You can just see these on the album "Dave's RAF Launch", (currently on page 5 of Albums) - between the main mast and the gun turret.

I use an old-fashioned "Bob's Board" - resistive mat - type of speed controller. Very 'old-tech' now and was concerned about heat build-up in the hull. So far it has worked well.

The air vents work on a simple aerodynamic principle, any water spills over the top decking run down to the stern and there is an internal lip in the vents to prevent any 'backwash' (probably overkill !).

You may be able to fit /hide something similar on your boat - as long as they have a supply of reasonably undisturbed air they should work...

Let us know how you get on

15/06/2020 11:01:59

On my little RAF Rescue launch (1/48 scale). I made the main superstructure removable. Space is quite tight inside...

This gives access to Rx, motor, coupling, top end of shaft, speed controller and LiPo (battery pack). Rudder access and servo linkage was more difficult. I fitted a separate screw down hatch at the stern for this at a later date.

It was easier for me as, being an own design, I made a lot of it up a I went along....I wouldn't worry too much about deck joins etc showing as once it's out on the water you won't be able to see them !

Have fun,

Dave C

Thread: Yacht Ardent
13/06/2020 10:44:47

Thanks all for the info',

I knew a lathe would be useful somewhere along the line !

I found that machining carbon fibre needs a good dust collection system otherwise my shelves etc get covered in fine carbon dust...whereas, with good old-fashioned ali' and brass I can get away with a dust pan and brush.

Not tried silver soldering yet but, have just bought a new TIG machine to try out...maybe on very low amps ? Otherwise, a butane /propane torch and the right flux and solder ?

Regards,

Dave

11/06/2020 15:36:59

Thanks both. I guess the next stage is to buy the plan from Sarik.

Eddie - I'll come back to you at 'mast time' - I have quite a stock of aluminium tubing now as currently making the rear wing spars for my sportscar. Is the mast likely to be taller than 1 metre ? If so, I'll need to make a join somewhere...

Regards,

Dave

11/06/2020 10:54:46

Thanks Ray - that's reassuring. I'm probably being over-cautious !

Coming back to lathes, is yours an ML7 ? I don't think I'll have room for a floor-mounted model, but, I'm currently looking for a bench-top one. About 2-3 foot between centres and 7.5" swing over the bed....any recommendations ?

Cheers for now,

Dave

10/06/2020 21:40:03

Thanks Eddie - a few further queries if you don't mind...

I've asked SLEC to quote for a laser-cut kit, but, on looking at your build thread there doesn't seem to be all that much cutting out to do - at least for the hull frames ?

I'm a bit nervous about making the sails though. Is this covered on the plan /article ?

Also, I'd like to experiment with vane steering and Arduino control at some point. Others have commented that I'll probably need a 'Y' shaped backstay to achieve this. However, I'll probably start with conventional RC initially.

One other thing I'd like is to have a small motor with folding prop as a 'get-out-of-jail' option mid-lake. I think Dave M suggested (in another thread) that Graupner used to do an all-in-one motor /shaft /prop unit that seems ideal...

Any views /experiences here most helpful,

Cheers,

Dave C

10/06/2020 15:57:08

Just found it ! "Under Sailing Boats and Yachts" (155) - with your SKU. - Most bizzare !

I think they need to work on their database search facility...

Dave

10/06/2020 15:50:01

Eddie - "MAR 3022" seems to relate to a group of plans on Sarik's website (about 5 pages worth), but, 'Ardent' was not amongst them ? This result was using their Search Box under 'Boat Builder Plans' section.

Bit of a puzzle ?

10/06/2020 15:33:10

Thanks both. I see SLEC and Sarik are advertising on the columns to the right of the posting windows.....

I believe SLEC do kits based on supplied plans for aircraft, so, will try them.

Eddie - does Ardent sail well ?

Ray - do you have any spare capacity on your Myford ? I'm looking for a lathe (and Mill drill) at present but not having much luck on the more affordable used market.

Cheers,

Dave

10/06/2020 10:39:43

Hi Folks,

Decided to go 'where the wind blows' for my next boat project..

A couple of challenges though :-

1. Quite like the look of "Yacht Ardent" which I think, originally, was a Model Maker plan. I have, previously, seen this on Sarik's website, but, the name "Ardent" seems to now refer to a different model (a tug ?).

2. Would quite like a quote from a laser-cut kit supplier to take said plan and deliver a kit (at least for the hull). Preferably, someone with boat experience !

So, if anyone could supply the MM plan code, (assuming it's a Model Maker one), I could try and run that by Sarik unless, perhaps, someone has a plan for sale maybe ?

Thanks for any assistance,

Dave C

Thread: Propshaft coming away from coupling
08/06/2020 22:45:26

Hi Jonny

The good news is that the flat doesn't need to be all that big - just enough for the end of the grub-screw to bite on is good enough. As they say above, best to use some 'Loctite' (or, similar thread compound) as well on the grub's thread.

I was a bit tight for space on my little RAF launch, so I took the rudder and prop shaft out to do it. Just a light touch on the bench grinder will do it, or, use a small hand file on the coupling end of the shaft.

If you have a fairly large hull you may be able to do it 'in-situ'. Lock nuts also seem like a good idea, although I didn't find I needed any...

Good luck with the mod'

Dave C

Thread: Help needed
28/05/2020 21:37:19

Hi Clive

I think the late John Pritchard was a specialist in this type of craft (especially the RAF one's)...

Might be worth a Google search in and around his name to pick up some supplementary links etc.

Good hunting,

Dave

Thread: Motor /Controller /Prop upgrade
28/05/2020 11:03:37

Good point Malcolm.

On the box (outer) - 'Futaba Attack II 27MHz' - it just says "Battery Eliminator Circuitry". I think the original instructions (if there were any ) have been lost...

For the Arduino, I'll probably use the regulated 'on-board' 4.8 volt supply. This will do nav' lights, search light and gun turret etc. duties, together with in-series resistors as needed.

I think I will do some "low-voltage" bench testing though just to determine what the operational limits are. I have a feeling it will be 'jitter' (or, full throw) on the rudder servo and some erratic wiper movement on the BB - another good reason to exchange the BB for an ESC perhaps !

Regards,

Dave

27/05/2020 21:47:52

Thanks Colin,

I'll have a go at getting them on Youtube then....

Sorry about the duplication above - don't quite know what I did there ! Please feel free to remove one (or, both ?) of them.

Dave

27/05/2020 13:00:06
Posted by ashley needham on 26/05/2020 15:55:22:

Well done Dave. Ashley's doubts are still there and I didn't say it would not work, just that it would increase drag so a performance boost may be had by....

Not sure how you could fit a 3mm shaft if you have a 2mm already (without reading all the posts!!),

Prop choice is far greater for the standard 4mm shaft size, so that's what I would go for, and an S35 two blade plastic prop will do you. The easiest way to a bit more power would be to fit a 480 motor (J Perkins do one) which is the same diameter as a 380/400 and shares the same mounting holes, but is longer and a bit more powerful.

The "modern" alternative would be to go brushless but would mean a new motor AND a new esc. Personally a 4mm shaft, 35mm prop and 480 is the easy choice. Please replace the Bobs board with a Mtronics 20A ESC, which will do ok.

Should be able to upload the link.

Ashley

Regarding the link - I have a small number of videos (around 10-20 second duration) of yesterday's runs to add to a link. Would I need to 'host' these on Youtube first,for example, or, is there a facility via the "Album" ?

D

27/05/2020 10:41:53

Hi Ray /Malcolm,

Yes, the Bob's Board does get in the way a bit, but, is part of the 'vintage' feel of the little craft. It does, however give a good progressive range of speeds if you keep the wiper /track clean... At the Tx end, the 'neutral' dead-spot is quite sensitive though and takes a bit of getting used to. I think this is where a programmable ESC would be nicer.

The Futaba packaging claim a BEC for the Rx and I power everything from the one Lipo. This may change when I have an Arduino on-board to control the gun turret ! (If I ever get that far...).

Yes Ray, the call of the wind is beckoning...

Dave C

26/05/2020 18:04:18

Hi Ashley

The boat does accelerate very quickly once 'up-on-the-plane' - probably near to what my reactions can keep up with at present !

In terms of the upgrade, (thanks for the tech' on this by the way), the shaft outer is 6mm diameter - hence, I felt I could safely drill out the bobbins at either end plus, the stern-end of the "Huco" coupling to take a 3mm inner. I'm wondering if 4mm would be pushing the clearances a bit ?. The boat is nice and water-tight now so, I'd rather not start to rip the insides out.

So, then, a motor upgrade, 3mm shaft (if I can find a suitable prop) and, possibly an ESC to replace the BB could be in order. The real essence of the project - as inherited from my son and his friend - is for a 'pocket money', fun-scale little boat. I think if I turn it into a 'cheque book project' the fun element will disappear...

Thanks again for your help,

Dave

26/05/2020 14:26:42

Well folks, the first run of the little RAF launch took place this morning on the upper reaches of the river Avon.

I must say it looked a treat in the early morning sunshine ducking in and out of the various overhangs on the river...

Trim-wise, it was a little bow-heavy to start with but, when 3/4 to full power was applied she came up nicely onto the 'step' (I know Ashley had his doubts about this..) and, rode bows just clear. It may need a little 'church roof' in the stern just to assist slow speed running.

I think the hull can handle a little more power - at the moment I have a 380 /385s motor with a 3-blade prop running a 2mm shaft / 7.4v Lipo and a Bob's Board.

Suggestions welcome for the next upgrade: eg 2-blade racing prop /3mm inner shaft (any bigger and I'll have to change the outer as well - rather not !). Also, the Bob's Board may be sapping a little power and there did seem to be a slight power hesitation when crossing back over the wake ?

Thanks to all for the help so far...I think it will be a nice cruising yacht next with an auxiliary motor /folding prop' combo and much bigger so that I can get my poor old fingers inside.

I have a few nice videos of this morning's runs taken by my wife on her smart phone - are we able to upload /link from the forum ???

Dave C

Thread: Help please! Inherited some boats!
25/05/2020 21:23:29

There could be 'gold' in them-there hills ! (Wooden hills that is.....).

Would that be Corby, Northants ? My son lives nearby,

I imagine if they're racing boats the engines will be 2 strokes ? However, if there's a '4' amongst them...I could be interested.

Good luck with your sale,

Dave C

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