Technical, Techniques, Hints, and Tips > BRUSHLESS Motors and Speed Controllers

Brushless repacement for MFA 850 Torpedo

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Hotglove:
I have a Dumas Chris Craft 1930 Runabout with 850 Torpedo. the size of the motor means that it cannot line up accurately with the prop shaft. a significantly smaller diameter motor would help.
I am probably asking too much but I would like to find a smaller motor with a noticeable increase in power, fairly quiet and cool-running (I don't want to pierce the hull for water cooling)
I would prefer an adjustable mounting, the MFA mount seems a bit crude. Would not expect the solution to be cheap.
Any suggestions?

canabus:
Hi Hotglove
I pickup a started Dumas Chris Craft 1949 Runabout (28 and 1/2").
Replacing all the running gear with a 4mm stainless drive shaft with a 32mm 2 blade CNC prop.
Brushless motor(28mm) from Hobbyking( Turnigy X2845 1980kv 792 Watts) and a car ESC 45 Amp(HK-45A)(you require a ESC program card(HK PROG-Card).
Twin Turnigy 1500mah 3S 25C Lipo batteries or a single Turnigy 2650mah 3S 30C.
I can the weight a bit more forward with the twin setup.
I have similar setup in a Sea Hornet (24 and 1/2") and it's a little pocket rocket.
With using the 28mm motor I made an alloy angle bracket and epoxy glue it to the keel.
Added a few pics from my Sea Hornet build from the model boat mag forum site.

Canabus

Hotglove:
Thanks for the input, my boat is 36” quite heavily built, has two PVC crew figures and runs on 2 5000 Lipos.
I am hoping to find a motor with significantly smaller diameter than the 850 (to allow better line-up with propshaft) but that has sufficient power headroom to run unstressed and, hopefully, avoid hot running.
Are there motors that have a well-established reputation for running quieter and cooler than average?
Thanks in advance.

jarvo:
Have a look on the Airtec site. They have a massive selection of motors and esc's, they also give the size and spec's of the motor's. You mention 2x5000 lipo's but not the voltage, how much space have you for the motor to fit into? that part is critical to make sure that the outrunner casing doesnt foul the keel.


Would it be possible to cut away a small part of the keel under the motor then reinforce the hull bottom with extra ply on both sides of the cut area??


Mark

canabus:
Hi Hotglove

As the 850 motor is 52m diameter, dropping to a 35mm brushless like I am using in my 34" Huntsman will give you far more power.
I am using a Hobbyking 3648-1450kv 1600Watts with a car ESC 100Amp(HK-100A) on a CNC 2 blade 40mm 1.4 pitch prop.
Single 3S 5800mah Lipo battery with a run time of a good 1/2 to 3/4 hour.
Very good turn of speed, over scale of course!!!!
I tested 3 blade 37mm prop, it gave better pick up at slow speed, but, prop the top end speed and increase the power on the watt meter.I have pictured my install with the water cool mount, but, it is not used.

Canabus

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