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delima
Posted: Jul 17th, '07, 21:18
by thereheis
well i had my props cut from 19x20 to 18x19 with a slite cup in the tip.now all i am gettin is 30kt at 3866rpm wot,i was getting at 3500rpm 30 kts and was only turning on wot 3833 gettin 31 kts on wot.i have 6lpa-stp2- 315 yannies with zf-gears 1;5-1 model zf-63a-16,,,any help on what it might take to get the 4100 wot rpm that they are needing ???i am gettin the noload spec rpm with no prob,,,, any help on this one ????
phil
Posted: Jul 17th, '07, 21:55
by Kingfish
I don't know if you have tried this.
They have a prop calculator that is helpfull.
http://boatdiesel.com/index.cfmiesel
If nothing else a Prop Shop should be able to calculate on their computer to get you close.
Posted: Jul 17th, '07, 21:56
by nic
Phil,
3500 for 30 knots does not sound right if you were revving out to 3833 and then getting 31 knots. How are you measuring speed and revs?
From what I have read from the guys I understand ideally you should be looking for around 3950 w.o.t. with the boat fully loaded, or at least 3900+ w.o.t. fully loaded, not 4100 - that is almost the no-load revs, we got 4180 no load and after a bit of playing are getting 3966w.o.t. half load.
At 3833 you were overpropped, and at 3866 you are still a bit overpropped - but you are heading in the right direction to get 3950 or so.
Most of the 315 installs have 2:1 so I haven't seen propellor comparisons for the 1.5:1s but it sounds like you are nearly there and at 3950 you'll be back around the 31 knots which sounds about right.
btw, I've never been able to get the boatdiesel calculator close, might be me though.
Good luck with it, hope this helps.
Nic
Posted: Jul 18th, '07, 06:16
by Bruce
Phil,
Call me today.
561-622-1736