flyroger

My Feedback: (7)

I have a PT109, 4 feet long with single prop. I am looking for information on what brushless motor to buy. Of course I want it big enough to run scale at full speed.

Hydro Junkie

You might consider running twin or even triple powered shafts then. This will allow you to use smaller and less expensive motors instead of one big one

yellow-bird

Hi Roger

If your boat is 4' long it is about 1/20th scale. Max speed of the original boat is about 50mph (about 1 boat length per second) so the scale speed would be about 2.5mph - pretty slow!.

Therefore you probably want faster than scale speed? Up to maybe 15mph actual speed is probably sufficient.

For comparison , the 41" ProBoat PT-109 model used pair of low-powered 550-sized brushed motors to achieve "realistic" looking speeds. To match this with a single brushless motor you should find that a standard 36mm diameter, watercooled "540" or "550" sized motor with 300-400W power is OK. You should also consider a suitable watercooled ESC. Depending on the motor and number of cells/ voltage you want to use, a 60A ESCshould be OK.

What size prop shaft do you have? This size motor is often split bewteen 1/8" (3.2mm) and 5mm shafts.

-yellow-bird

Saxondog

Twin props and shafts would be much better not only in cost and power but in the performance.,It's a PT Boat,needing twin power for the control and to match the V-HULL design.

What hull design is your boat? Are we talking about the American type or German? My Boats are 1/32 scale 30"oal Lindberg Kits,but their fast and fun.

Here is a link you might find interesting-
http://www.ptboats.org/07-0-05-museum.html The Museum Head Quarters is Located in my Hometown of Germantown,Tn. excellent people and most of the hard records are at this location.

Several great links and information on the boats. Drive systems are many and can be expensive.Best of luck with your boat.

rthalls

My Feedback: (63)

I see you built the Limburg PT boat , thinking about it , is it a lot of scale ? can;t decide between it and the wood ones thanks

flyroger

My Feedback: (7)

What i have is a Dumas Pt 109. It is the 4 foot version and came with a fiberglas hull. It does have a lot of scale, but where I live in a 5 month winter it was nice to keep me busy the whole winter.
I did finall purchase a brushless motor from Hobby King with a speed converter. ( 125 Amp. ) Now with one prop I can get better than scale speed. I now can run a battery 24 Volt at 5.0 Amp hour and get a very good run time. To say the least a real pleasure to run.............

rthalls

My Feedback: (63)

I have the same problem about winter and need something to build , I have a 30amp 16v ESC and brushed motors so want to build a boat around them and thought the Limburg pt would be light for a longer run ----------- still looking for the right boat