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Prop from transom distance - 12/15/2012 1:44 AM   
Johnwhite84



Posts: 92
Joined: 10/4/2010
Last Login: 12/18/2012
From: Granite city, IL, USA
Status: offline 		Ok guys got a fairly simple one. I'm scratch building a very small 16in hull length mono hull. I do not have a strut mounted just the stuffing tube exiting the transom. My plans are to go as fast as the hull will allow. As a very rough starting point I currently have it mounted to the tip of the stuffing tube to the transum just shy of 2 inches or 12% of the length of the hull. Curious how short or long I should go.

Thank guys

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RE: Prop from transom distance - 12/15/2012 1:58 AM   
Mikeup


 

Posts: 374
Joined: 1/13/2011
Last Login: 5/13/2013
From: Clive, IA, USA
Status: offline 		I deleted as i didn't want to give bad advise but i really didn't give you bad advise. My lenght works perfect for my boats, but i use shorter turn fins and no trim tabs and longer  struts . I also have motors placed where i need them and al l works out. I'm retired and i've become very addicted to perfection on performance of such. Paul 785 is a GURU and i respect him for it. Sorry!  _____Forgot, i run full strakes on all my boats and that works in conjunction with 3" struts  with 2 degree down or neg. angle.

< Message edited by Mikeup -- 12/17/2012 3:16 PM >

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RE: Prop from transom distance - 12/15/2012 2:19 AM   
Johnwhite84



Posts: 92
Joined: 10/4/2010
Last Login: 12/18/2012
From: Granite city, IL, USA
Status: offline 		This started out as my rescue boat for my nitros but of course speed got the best of me. Has 2900kv brushless turnigy 28-45. Tested it with 3s lipo and only pulled 270W 26A with x434. leopard water jacket. turnigy marine 60A esc. .98 drive. Have 5 props to test. 430,431,434,437 and a 632.

2 1/2 inches just seems rather long to stick out from the transom on such a short hull. Is that 2 1/2 from transom to tip of drive shaft or from transom to drive dog ?

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RE: Prop from transom distance - 12/15/2012 9:01 AM   
martno1fan



Posts: 11153
Joined: 1/20/2005
Last Login: 5/18/2013
From: blackpool, UNITED KINGDOM
Status: online 		You should be fine at 2".
Mart

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waveridermouldings

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RE: Prop from transom distance - 12/16/2012 9:56 AM   
785boats


 

Posts: 305
Joined: 8/7/2007
Last Login: 5/18/2013
From: Brisbane, AUSTRALIA
Status: offline 		John.
The general rule of thumb is 10% of the hull length from transom to face of the prop. 1.5" - 1.75" should be ideal for a 16" hull.
If the prop is too far away from the transom the hull tends to skip a bit in the corners at full noise & become unsettled.
I've not built a hull as small as 16" but I have two identical Delta Force 25" racing hulls. One of them is set at 2" (strut) & the other is at 2.5" (stinger).
The shorter strut actually handles better than the one with the longer stinger. Even though 2.5" is 10% of the 25" hull.
I'm going to replace the stinger with a shorter strut for next years racing.
Even with some of my larger 33" & 36" hulls the ones with the strut/stinger length slightly shorter than 10% seem to be a bit more stable in the corners.
Hope this helps a bit.
Paul.


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RE: Prop from transom distance - 12/16/2012 2:43 PM   
Johnwhite84



Posts: 92
Joined: 10/4/2010
Last Login: 12/18/2012
From: Granite city, IL, USA
Status: offline 		That helps a lot! This is not a race boat so getting it 100% dialed in are not my intentions. I will shorten it up to around 10% and if she performs then that's where I'll stay. If she dosnt feel quite right ill shorten her up just a bit more. My previous measurement was tip of the stuffing tube to transom. Now I know where to measure from. Tanks for the help!

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