Model Boat Mayhem

Mess Deck: General Section => Model Boating => Topic started by: Glyn Roberts on June 07, 2016, 05:15:02 pm

Title: Difference between Props.
Post by: Glyn Roberts on June 07, 2016, 05:15:02 pm

What is the difference between 2 blade SR type high speed GFN Propelers   &   2 blade X type high speed GFN Propelers.                                     

How does the difference affect a boat.    Need to know this before ordering the Props.

Thanks and regards Glyn

Title: Re: Difference between Props.
Post by: Subculture on June 07, 2016, 05:36:48 pm

Pitch is coarser on the x type. Should give more thrust, but will also create a higher torque moment, e.g. twist the boat over more if its single screw, and will also load the motor up more.

Title: Re: Difference between Props.
Post by: roycv on June 07, 2016, 05:44:18 pm

Hi, I seem to remember that the finer pitch props have a 1.4 X prop diameter pitch and the coarse ones 1.7 X diameter of prop. Stand to be corrected though.
regards Roy

Title: Re: Difference between Props.
Post by: Subculture on June 07, 2016, 05:58:48 pm

1.2 and 1.4x prop diameter usually. 1.7 would be very coarse, sort of thing reserved for steam driven boats or heading towards surface piercing prop pitch.

Title: Re: Difference between Props.
Post by: inertia on June 07, 2016, 06:45:59 pm

SR = better acceleration, lower top speed, less torque reaction, less current draw
X = the opposite of all of those, all other things being equal

DM

Title: Re: Difference between Props.
Post by: roycv on June 07, 2016, 11:28:24 pm

Hi I use the small diametder coarse pitched props for my motorized sailing yachts as when stationary they cause less drag.
regards Roy

Title: Re: Difference between Props.
Post by: Glyn Roberts on June 08, 2016, 05:44:31 pm

Thanks for all reply's,  good job I asked rather than sailing on in ignorance as the information turned out to be critical.

Regards and thanks Glyn