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01scarab29 07-29-2014 09:14 PM

PropShaft Centerline
 
What do you guys have for prop shaft height ? wondering about boat lengths compare to shaft height

Griff 07-30-2014 12:55 AM

2-6 inches below the bottom on most single engine boats. It depends on if its a stepped hull, how much hp and how big of boat.

A 29 non step with 500hp is going need to be a lot deeper than a 29 stepped hull with 800hp.

Deeper gives more leverage to carry the bow and reduce the wetted surface. Stepped hulls don't need to carry the bow as much.

01scarab29 07-30-2014 08:33 PM

29' Scarab, twin 383,s 400hp/425tq ,,,, less than 5' of boat in water at WOT

hullofjustis 08-04-2014 10:35 AM


Originally Posted by 01scarab29 (Post 4162737)
29' Scarab, twin 383,s 400hp/425tq ,,,, less than 5' of boat in water at WOT

she ought to run good with that power? what is you r reason for asking? are you considering 2 inch shorties?

01scarab29 08-04-2014 08:05 PM


Originally Posted by hullofjustis (Post 4164950)
she ought to run good with that power? what is you r reason for asking? are you considering 2 inch shorties?

Run's 73mph with a 25p mirage ,,,, reason is I'm thinking tremendous drag,,,, I'm 7 1/4' below hull ,,, I am thinking shorties,,,,,, THOUGHT's ,,,,,

dereknkathy 08-07-2014 06:07 AM


Originally Posted by Griff (Post 4162204)
2-6 inches below the bottom on most single engine boats. It depends on if its a stepped hull, how much hp and how big of boat.

A 29 non step with 500hp is going need to be a lot deeper than a 29 stepped hull with 800hp.

Deeper gives more leverage to carry the bow and reduce the wetted surface. Stepped hulls don't need to carry the bow as much.

is that 2-6 inches below hull where drives are, or below lowest point at keel? edit; ok, that is single engine spec. well, question still valid for his twin engine scarab. 7-1/4 inches sounds a little deep to me.

hullofjustis 08-08-2014 09:41 AM

the black hawk drives on p29 were shorter drives than a bravo 3 and that boat ran great speeds with minmal power i would recommned shorties

drpete3 08-08-2014 10:11 AM

No extension box correct?

hullofjustis 08-08-2014 11:08 AM

i would try the shorties first and see what you get. if you don't like the results or want more then go with an extension boxes i put 3 up imco boxes on my panther and had to change the engrine mount location, so unless you have to pull an engine i would wait on them.
i would be very interested to see how yours runs with shorties. i set my panther up to be 1 1/4 below the bottom with shorties and 3 1/4 with standard length with the 3 up boxes

01scarab29 08-08-2014 04:38 PM

correction, runs 73mph with 23mirage plus,, run 25 on long poker runs for better cruise, measurment is inline with drives ,, i am wanting to buy shorties, prefer case only ,, would like -3, thinking i can always add ,, ,,,, also has anyone with twins run props inward ? thoughts ?


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