I have a old MRC Thunder Streak that comes with dual RS540s running to a gear box for a 1.5 to1 gear reduction. It is supposed to use 2 7.2v NiCad packs to power and has the micro switches to turn the motors on or off. I want to replace the power and motor system with a single brushless motor and a esc.

Any suggestions on what I should be looking at. I am not real familiar with the BL motor rating or sizing. In the instructions it says that with the stock power/drive it should go around 25mph. Bumping that up some would be part of the conversion. I don`t know what size prop is included as the manual does not say. How do you measure the prop?

Thanks

Hi Skylane,

Some pictures of the interior, showing how much room is available and some shots of the transom and side, to show the type of drive built in would help to make sensible suggestions.

Keep in mind ABS gets brittle over time if it hasn't been covered in paint.
Any excess motorisation will reduce it to rubble when you hit something in the water (or the shore)...

Regards, Jan.

Agree with Jan... Some pictures will be helpfull to give you correct suggestion.

Here are some pics of finished boat I found on net. The boat is 28 inches long. the 2 battery packs required for the boat sit in front of the gearbox flat longwise.

Hi Skylane,

Having seen the pictures, I seriously doubt if this design is suitable for upgrading to brushless power.

The steering outdrive isn't up to handling more power.
The rigid shaft limits the possibilities of adjusting the propangle.
All trailing edges are round (due to the vacuum forming) and need to be filled and sharpened to avoid the hull sucking itself onto the surface.

Due to the inner tray you don't have access to the bottom innards, making reinforcements rather difficult.

Upgrading an ABS hull requires beefing up the running surfaces and the transom, changing the rigid shaft to a flexshaft/strut combo with a seperate (offset) rudder.

Basically it's major surgery and quite a lot of work.

The choice is yours...

Regards, Jan.

Thanks for your opinion... I think I will take your advice and just go stock with it and just have some fun. I was looking at going BL because I could use Lipo for power but looks like I will be hunting some Nimh packs. Problem is the old school packs are more expensive than new lipo packs are... go figure.

Thanks again.

Hi Skylane,

You can use Lipo's to power brushed motors without any problems.
Just use a Lipo saver/buzzer to detect when the lipo's are getting depleted, to avoid damage to your packs.

Chances are the boat will run better/longer due to the lower weight of the Lipo packs.

Regards, Jan.

Just time your runs and you should not have any trouble .