Model Boat Mayhem

Mess Deck: General Section => Model Boating => Topic started by: Hotglove on August 07, 2018, 08:58:19 pm

Title: Graupner aluminium dog-drive prop
Post by: Hotglove on August 07, 2018, 08:58:19 pm

does anyone have experience of these props? I have tried several plastic props on my Dumas Chris Craft 1930 Runabout and was torn between a 35mm Xtype and 40mm version of same. The 35mm version ended up with a small chunk out of it, which confirms my gut instinct to go for a metal prop once the size was confirmed.
I am limited by the 3/16 shaft size, so the obvious choice is Graupner Ali and I am thinking of splitting the difference and going for a 38mm version.
Motor is a Turnigy 3648 1450 running on 3s Lipo 2x5000mah in parallel.
I was a little concerned because the Prop Shop website stated that aluminium is not recommended for dog drive props.
Thank you

Title: Re: Graupner aluminium dog-drive prop
Post by: Andyn on August 08, 2018, 02:15:24 am

Cast ally maybe, but cnc props are a whole different animal. Are you running surface drive on this thing?


I run cnc props from Offshoreelectrics, I've found them cheaper to buy in the US than in the UK...


https://www.offshoreelectrics.com/categories.php?cat=CNC+Propellers

Also bear in mind that a cnc prop of the same size as a plastic one will behave entirely differently. Not only will it more likely have a different cup, blade shape and pitch, but plastic props flex and flatten under load.

Title: Re: Graupner aluminium dog-drive prop
Post by: Hotglove on August 08, 2018, 05:12:43 pm

Hi Andyn
Thanks for the link, I had been doing a lot of head scratching and have ordered a 3 blade 38mm CNC alloy prop from them.
The boat is a fairly heavy example, I have added crew and props but the 3648 1450 is a great motor.
I recently started running a Robbe Turo with brushless motor as a learning boat, I love the contrast between the two, The Dumas is like a big, heavy V8 four seater touring car and the Robbe skates round the lake like a Caterham 7.
At the moment I am running the Dumas standard 3 blade bronze prop which measures 35mm but is much finer pitch than the racing type 2 blade props that I have tried.
The Dumas prop gives significantly less performance than the X types but sounds and feels very sweet to run, the RPM at max is 17000 compared to 18400 with no load,
Hopefully the CNC prop will be an interesting development in my and my boat's future
Thanks again.

Title: Re: Graupner aluminium dog-drive prop
Post by: Hotglove on August 24, 2018, 08:59:22 pm

CNC prop arrived today, it took 3 days to get from Massachusetts to Heathrow, and 12 days to get from Heathrow to Rochester.
Much finer and lighter than expected, hope to get it on the lake tomorrow.

Title: Re: Graupner aluminium dog-drive prop
Post by: Hotglove on August 25, 2018, 04:41:40 pm

The new prop is amazing, 38mm, 1.4, light as a feather, huge increase in performance with the bonus of much cooler running.

Title: Re: Graupner aluminium dog-drive prop
Post by: Andyn on August 26, 2018, 01:39:31 pm

Glad to be of assistance :-))