MM337

[cheddar24manParticipant @cheddar24man]

Thanks Richard, very nice. Do I see a cooling system in there, is this essential?

Could you give me details of the installed equipment please, years since I’ve had anything to do with brushed motors.

[Richard SimpsonParticipant @richardsimpson88330]

Unfortunately this was put together by a gent who passed away a good few years ago now so the only information I have is what you can see in the pictures.  I have tried the model with the cooling not running and, while the motor runs warm, I wouldn’t say it gets concerningly hot.  I think the cooling is more of a precaution rather than an essential but I do use it all the time.  I guess its a bit self regulating really as, if I run it flat out, I only get around 15 to 20 minutes out of it.

At one point I played with the idea of using a lead acid battery but I’m certain I won’t get it to perform as well with the additional weight so I’ve been tempted a couple of times to go for adding two more Nimh batteries aft of the existing ones, connected in parallel with them to give double the capacity while maintaining 12V.  I’m hoping the weight aft of the original batteries won’t upset the performance too much.  What is holding me back is the fact that its an expensive experiment.

 

 

 

[Colin BishopModerator @colinbishop34627]

Richard,

If you are only getting 15-20 minutes run time on a 5Ah battery it suggests that the motor is pulling a heck of a lot of amps even allowing for the battery being a bit old by now. The speed controller specs look a bit unlikely to me:

https://www.mantuamodel.co.uk/products/radio-control-kits-and-parts/speed-controllers/1768/aquapower-280-detail

280 amps continuous?! The Mtroniks ones only go up to 40 amps. Dave Milbourn’s Huntress was fitted with a 2600MAh LiPo pack and brushless motor. You can see the performance here about 7min 20 secs in.

(incidentally, this boat will be shortly offered for sale in working order.)

Edit: the boat above is in fact a 1:12 scale version of the Huntress as per the original feature plan, the SLEC kit is 1:8 scale but the battery is the essentially the same for both.

Colin

[Richard SimpsonParticipant @richardsimpson88330]

Part of the problem was a cell down on one battery, which has now been repaired.  It will be interesting to see how much it has improved at the next outing.  I don’t trust any of the specs of these high amperage Chinese speed controllers!  Its been in for many years and does the job so it can stay for now.  I might put an Mtroniks in though if duration does not improve next test.

[John W EParticipant @johnwe]

Hi there, I have a feeling the motor in your boat, Richard, could be one of these – it does look very similar.  A Johnson fan cooled job.

They are a good motor, but, a bit thirsty though.   If you are querying your speed controller; to give you a comparison, here is a photograph of the speed controller in my Crusader model.  It runs on 150 amp; at 50 volts and the wiring is 10Awg thick wire – it is pretty thick wire.   When I run this, the wires get warm.   The plug in the picture is an anti-flash plug for reducing the spark between plug and socket when connecting as you cannot put a switch in between batteries and speed controller for fear of melting the terminals.

Expo / Johnson 683 High Power Motor 26055, Model Shop Leeds

 

 

 

 

[cheddar24manParticipant @cheddar24man]

That Expo / Johnson 683 High Power Motor 26055 is one cheap motor John! £5 in the Leeds model shop!!

What model is that red/yellow mother in John? I can just read 90EDF on it and that is a ducted fan motor. Not much good for driving a prop me thinks!

[John W EParticipant @johnwe]

Hi the fan is a 12s 90mm ,and the model is of

John Cobbs CRUSADER  

 

[cheddar24manParticipant @cheddar24man]

I notice in JohnWE’s picture that the sides have been trimmed down to the deck location and the deck is being fitted OVER the sides.

Is this the norm or could the deck be fitted UP TO the sides and then the sides trimmed down to the top of the deck?

Taking the sides down to the deck location first would make making the deck location nice and flat/curved as applicable, much easier.

Does it really matter which way I go?

Cheers.

[Ray Wood 3Participant @raywood3]

Hi Ched,

Trim/plane the side sheeting down to the gunwhale strip the deck goes over it, and that is then trimmed to the edge of the hull 🙂

Regards Ray

[cheddar24manParticipant @cheddar24man]

Thanks Ray, that’s what I thought, makes it easier to clamp the deck in place!

Another query, I have put it elsewhere but not had a reply yet, where should one locate the water scoop for ESC cooling? The rudder will be immediately behind the prop but there could be room for the scoop in front of the rudder, just behind the prop. Is this the best place? Off to the side it would only be really effective when the boat was at speed.

Cheers.

[cheddar24manParticipant @cheddar24man]

It’s coming along. Deck fitted yesterday, seem to have it right. Now to install the hatch supports and sand the edges flush with the sides!

[Richard SimpsonParticipant @richardsimpson88330]

Just going to mention something that is best dealt with at this stage rather than later.  If the steering servo fails at some point in the future, how do you replace it?  Would it be better placed further aft so it is accessible within that aft hatchway?

[Ray Wood 3Participant @raywood3]

That’s a good point raised by Richard, most of my access problems are self created 🙂 but in fairness I have never had a boat servo fail (so far )

The hull and deck look great btw , a nice stage to reach

Regards Ray

[cheddar24manParticipant @cheddar24man]

Good point Richards, didn’t think of that but, as said, in 60+ years of using servos, from cheap plastic in wings to HD metals (which this is) I’ve never had one fail (tempting fate there!!!

I think I’ll take my chances🤔

[John W EParticipant @johnwe]

mmmmmmmmmmm are you going to tempt fate?  Be very very careful.   I have tempted fate more than once, positioning servos under decks that you cannot get at and must confess I have never had any trouble with the servos operating or breaking down – until – a couple of months ago, doing the annual model dusting – HMS Exeter was on the bench; cleaning mountains of dust off so I decided to check all the electrics and yes you are right – the rudder servo did not work.  Not going to blame the servo; was it the actual radio receiver so, that was exchanged.   Everything else worked apart from the rudder servo.   After a bit of twiddling about, putting the servo tester on the plug of the rudder servo there was a grinding noise.  On Exeter the rear deck was planked with 2mm wide planks.   No real way of camouflaging the hole I was going to have to make through the deck; such a heartbreak.   So, after a long debated discussion with myself the pros and cons I actually cut through the deck to gain access to the servo and linkage.  When I stripped the servo down, there was the smallest bit of what looked like a broken tooth from one of the gears jammed in the gear mechanism; so, I think from now onwards when I fit a rudder servo, it is definitely going to be where I can gain easy access to it on any of my future models.

 

John

[Colin BishopModerator @colinbishop34627]

I have always worked firmly on the principle that what goes in must come out. It has paid off on several occasions.

Colin

[cheddar24manParticipant @cheddar24man]

I get the message guys, I’ll make some. changes!!

Cheers.

[Dave ReedParticipant @davereed72029]

Hi Ched,

I’ve also had a steering servo fail, it would intermittently lock in a turn until the boat was recovered and power cycled. Replacing the servo sorted the issue.

Before you start chopping lumps out of the deck, it looks to me as if you have space to add a servo behind the current one should it fail. Just leave the failed one in situ if you cant easily remove it. You only really need one pushrod with a single rudder.

Anyway, about access to that motor……

Dave

 

[cheddar24manParticipant @cheddar24man]

🤣🤣I can actually remove the motor if need be😎 and good thinking about the servo!!

cheers🤔

[Ray Wood 3Participant @raywood3]

Dave,

that’s is a good idea 🙂 the forum seems to be picking up some momentum now with good solutions !!

Regards Ray

[cheddar24manParticipant @cheddar24man]

New (old) blood come on board 🤣🤣

[Richard SimpsonParticipant @richardsimpson88330]

If you’re really lucky, I reckon you might just have enough space to use the existing wooden block as the forward mounting and just add one more block for an aft mounting.  Work out how much space you need and see if you can find a servo to suit the space.

[Colin BishopModerator @colinbishop34627]

If the steering servo fails at some point in the future, how do you replace it? Would it be better placed further aft so it is accessible within that aft hatchway?

It is also an option in some models to mount the steering servo under the main hatch amidships with a long rigid or sleeved link to the rudder head to make it accessible. Direct access to the rudder stock is always essential as if the rudder takes a knock then you need to be able to effect repairs. In the second photo the rudder servo is actually mounted ahead of the motor (which itself is mounted on the underside of the deck!). You can see the rudder link length adjustment screws alongside the motor. (click on the images for a larger version).

Colin

 

 

[Dave ReedParticipant @davereed72029]

Having got the ball rolling with options, let’s chuck another cat into the pigeon loft…

If you use an aircraft style ‘snake and clevis‘ then the servo can go pretty much wherever you want. No line of sight needed from servo to rudder.

Just a thought

Dave

[cheddar24manParticipant @cheddar24man]

Plenty to think about guys but right now I’ll leave it where it is. As said, if it fails I have room to mount next to the tiller.

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