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[zooma]

The bottom picture shows the replacement engine bed that I made and wanted to use, but the very low prop shaft angle of this Vic Smeed steering hull made it impossible to fit...........so plan B is shown in the first two pictures!

[zooma]

Some plywood cheeks were cut to fully support the new engine plate before it was Araldited into place and when dry it was given a coat of Bondaglass resin and some chopped matting.  Nothing too thick as I didnt want to add too much weight to the hull.

When dry the re-worked area of the engine bay was painted so (hopefully) this will be the last time I need to make any more changes to the inside of the hull - unless I find that the 4mm prop shaft will not handle the extra power of the new motor - and if that turns out to be the case - I will fit the 5mm shaft that I have made .

The recycled 5mm prop shaft that I have "in reserve" was made by cutting down an old pre-used 2BA prop shaft and pressing in a new pair of 5mm phosphor bronze bearings. If I do need to use it in this hull I will fit a new 5mm stainless steel inner shaft.

The new engine bay layout has been revised to allow the use of a MaxiFlex coupling this time to bring it inline with my other powerboat installations. The MicroFlex coupling will not be wasted - I have an old Aerokits Patrol Launch that I bought in 1971 from Exmouth Models - its about time I finished this "slow build" 

[zooma]

Remora sailed again today with her new Turnigy 3542 1250 motor with a new water cooled engine mount in the revised position to take any front mounted brushless motor.
A new Turnigy 20-30c discharge 5000mah 3C LiPo was used and the speed remains pathetic-slightly better than with the previous rear mounted Turnigy D3536/6 1250 motor.
The ESC is still the 90A Seaking - the same as used in my blistering fast (in comparison) Inception so that should be fine?
I tested 45X, S45 and 40X props and it hardly made any difference at all. The motor does not rev enough.
Maybe the 20-30C discharge battery is the problem?
Any ideas?
….and does anyone have the claimed power output for this Turnigy 3542 1250 out-runner?

[JimG]

I don't see the C rating of the battery being your problem, if the 20C rating is to be believed a 5000mA battery is  rated as 100A continuous. Lack of revs is either too low a voltage or too low a kV rating. Try either a 4S pack or a similar sized motor with a higher kV  rating.
Jim

[tonyH]

I was just wondering whether the hull shape is too "sticky" and doesn't allow the hull to break some of the drag caused by surface tension. I'd almost try sellotaping a thin wedge onto the hull to see if a step-hull effect gave any difference.Just an idea Adding more power/prop size etc may follow the law of diminishing returns.

[zooma]

Harry has let me know that the Turnigy 3542 1250 motor that I have just fitted has a maximum power output of 665 watts - the previous Turnigy had a max power output of 486 watts so the power increase is very slim and that is reflected in the marginal performance increase I can see.

[zooma]

I was just wondering whether the hull shape is too "sticky" and doesn't allow the hull to break some of the drag caused by surface tension. I'd almost try sellotaping a thin wedge onto the hull to see if a step-hull effect gave any difference.Just an idea Adding more power/prop size etc may follow the law of diminishing returns.

You may be right Tony - I was expecting this little lightweight to fly along.


If I still have the motor I took out of Rapier1 here I will bung it in and see what happens!


Failing that I will change the motor when I get home after the bank holiday.

[canabus]

Hi Zooma


What's the motor from the Rapier ???


I will see if I can find the specs ???


Harry

[zooma]

The motor that I took out of Rapier1 was the Turnigy 3648 1450.

[canabus]

Hi Zooma


 Holy Hell, you will have it flying with the 3648-1450 on 3S with a 40/45mm prop!!!


Do not try it on 4S, it would be totally insane !!!!

[tonyH]

Just think what you could do with 1600 Chinese watts!

[canabus]

Hi TonyH


I have a 3648-1450 in my Precedent Huntsman on 4S and near sits up on the prop on 4S !!!!


And it's rated at 1600 Watts on 6S !!!!


Harry

[zooma]

That motor was very fast in Rapier1 so it would murder the Remora!


Maybe I should put it back in Rapier1 and see what the Surpass 3548 1100 goes like in the Remora?


It still shoves Rapier1 along at a tidy pace but it is not as violent a the Hot Turnigy!


Does your reference bank have the power rating for this Surpass by any chance Harry?


It would make an interesting comparison !

[canabus]

Hi Zooma
The 1100kv is 500Watts on 4S.


If you scroll down their page you find the specs on the motors.


I am putting a 1250kv in the Wavemaster(34") on 3S.
Keeping the two 1450kv for a Spearfish, 2100 Watts on 4S may get it moving !!!


Harry

[zooma]

Harry has let me know that the Turnigy 3542 1250 motor that I have just fitted has a maximum power output of 665 watts - the previous Turnigy had a max power output of 486 watts so the power increase is very slim and that is reflected in the marginal performance increase I can see.

This is making no sense at all.


The Surpass 3548 1100 that shoves the much heavier and bigger Rapier1 along at a really good pace (on 2 cells!) is only rated at 590 watts, but the Turnigy 3542 1250 motor that struggles to push the smaller and lighter weight Remora along (on 3 cells!) is rated at 665 watts!

[tonyH]

What is the weight of the model, Bob? The original came in at 5lb1oz according to the VS build write-up in MB and was powered by an OS19 3.5cc glow. The motor equates to about 300 watts apparently. The film here is basically the "as designed" which might be useful since it should be close to what VS intended. https://www.youtube.com/watch?v=jbTdqq582rg
 

[zooma]

I don’t have any scales with me here in the van Tony, but my Remora is far less than half the weight of Rapier1.


The Remora running at Fleetwood is what I would expect mine to run like so I need to keep checking to find out why it doesn’t go very well.


It can only be the motor or maybe the ESC so when I get home I will change them both and resolve it by the process of elimination, and I will weigh it and let you know what it comes out at, but it is definitely not a heavy boat.


I have seen lots of fast Remora’s over the years so I don’t believe the sluggish performance has anything to do with the hull.

[tonyH]

I appreciate that Bob but from the pics she doesn't seem to run as cleanly as she should? Just something else to eliminate

[zooma]

I appreciate that Bob but from the pics she doesn't seem to run as cleanly as she should? Just something else to eliminate

Every idea is a good idea - until proven otherwise 


………so right now I am happy to gather any ideas or thoughts that will help me to identify the problem- then I can fix it!

[Leaky Bottom]

Have you checked your battery voltage under load, it could be fine with no load but if you have 1 duff cell it could bring the voltage down when running

[zooma]

Have you checked your battery voltage under load, it could be fine with no load but if you have 1 duff cell it could bring the voltage down when running

No I haven’t checked that Leaky.


I bought two new LiPo packs for this new boat and was impressed to see how equal each cell was balanced with each other during and after being charged in both packs, but I have not checked either of them when they are under load in the boat.


When I find a method of checking this I will do it. I also have other 3 cell packs that I use on a small fast plastic Vector 80 so I will try using these LiPo packs on Remora and try the new packs in the Vector 80 so I can cross check them in each boat.

[zooma]

I appreciate that Bob but from the pics she doesn't seem to run as cleanly as she should? Just something else to eliminate

Hi Tony,


The hull shape is built from the original Dec 1964 Model Maker plans with no modifications and it is built “light” so it should run OK.


I have used the same paint on the underside as I used on Rapier1 (and that performs really well) so I don’t think there is anything to cause any extra drag, and the centre of gravity balance point is where it is shown on the plan when the LiPo is fitted



Remora does not have any strakes specified in the design so I could add some to see if that could help but at the moment I just think that I need more power.

[zooma]

I tested Remora again today and changed the tx to give a fresh ESC set up, but it made no difference- the boat was still slow.
Both LiPo batteries were then tested in the Vector 80 where they performed superbly - very fast and with excellent endurance, so the LiPos are not the problem and the motor will be changed next.

[Leaky Bottom]

Are you able to take any video of your Remora to give an idea as to it's performance.


Have you checked if the coupling is not slipping on the motor shaft or the propshaft (if it's not threaded).

[zooma]

Are you able to take any video of your Remora to give an idea as to it's performance.


Have you checked if the coupling is not slipping on the motor shaft or the propshaft (if it's not threaded).

Hi Leaky,


I filed a “flat” on the 5mm motor shaft to prevent any movement before I installed the motor and I did check that the Powerflex coupling was tight and not slipping.


Until (or if) I need to upgrade the prop shaft to 5mm the current shaft is threaded 4mm with the customary lock nut against the coupling. I also checked to make sure there was a little “end-float” to ensure the shaft was turning freely and not binding. All of this checks-out OK.”


I do have a short video of the boat taken on my iPhone, when I get home I can send it to you if you send me a PM with your email or iPhone info.


Stay safe,


Bob.