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Author Topic: guestimat of prop size  (Read 1759 times)

gwa84

  • Guest
guestimat of prop size
« on: December 19, 2011, 09:59:31 PM »

enybody got a rough idea what diamiter sefice prop to go for with an sc61 cheers  :-))
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ids987

  • Guest
Re: guestimat of prop size
« Reply #1 on: December 20, 2011, 04:50:23 PM »

It depends - to some extent, what boat. I'm taking a guess at a deep vee of some kind. It will still depend a little on the size, but sticking a finger in the air, I would say that a fair guesstimate / starting prop would be a X455. The SC engines have quite a lot of torque, and I reckon a SC 61 should pull a 2 or 3 blade X455 fairly easily. You may well be able to go bigger than that - once you start to get the setup in the right ballpark, but always best to start off with a reasonably easy load.

Ian
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Craig Dickson

  • Guest
Re: guestimat of prop size
« Reply #2 on: December 20, 2011, 08:00:37 PM »

Hi I can only comment on a heavy 4 foot long wooden Huntsman 31 fitted with an SC61. It runs well on the following two bladed props, 2220, 2025 and 2027.

The 2027 is very high pitch. This clips shows the boat running on it:

http://www.youtube.com/watch?v=2reXeZYxb8o

Cheers
Craig
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gwa84

  • Guest
Re: guestimat of prop size
« Reply #3 on: December 20, 2011, 08:39:40 PM »

hi peeps thanks for the info the boats a 46 ich wild thing more a shallow v   wood hull bult from plans  :-))
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ids987

  • Guest
Re: guestimat of prop size
« Reply #4 on: December 20, 2011, 09:16:43 PM »

hi peeps thanks for the info the boats a 46 ich wild thing more a shallow v   wood hull bult from plans  :-))

I think the V angle of the Wild Thing puts it in Deep Vee territory, and in the sort of size bracket I was thinking of, so I think the X455 won't be far wrong - as a start.
Findings at our club have been similar to Craig - for submerged drive. We've had SC 61s pulling props in the 2027 or 2028 region - which takes a lot of torque. For racing engines, the pitch of those props is in the .90 size bracket. Similarly, a sport .46 engine, will often pull almost as much prop as a racing .67. 
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gwa84

  • Guest
Re: guestimat of prop size
« Reply #5 on: December 20, 2011, 10:41:31 PM »

that whas my next dilema weather to use the sc or an ops .40 i have its just a case of weather thepawer increes of the sc will justify the whait gain  :-))
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BJ

  • Guest
Re: guestimat of prop size
« Reply #6 on: December 25, 2011, 10:04:09 AM »

.... and yet again
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