Hey 6LP Owners, What prop are you turning?

[RobS]

I guess my last topic "Prop, Pitch & Cup" was more of a broad discussion on the topic.

I am specifically looking for feedback from 6LP 28TE owners regarding prop pitch & cup and WOT rpm.

I assume it will all be 19" dia LH 4-blade props, either 19x19, 19x18 or some pitch in between. And cup specs too.

Thanks in advance for the feedback.

[mhanna]

My prop was stamped 19x19 and it is a 4 blade and I feel its working great. It could have come from the factory like that and been modified they probably would not re-stamp it. When the boat comes out of the water I will be taking it for a propscan to see.
In the beginning of the year my tach was checked and it was very close to accurate. I turn just under 4000 rpms at wot with full fuel and 2 people.Like I said above I like the way it works and am not looking to change a thing.
When I find out my results of the scan I will let you know.


Matt

[Anthony1013]

Our 1999 6LP is the 300HP version and we're turning a 19x19 LF with a medium cup. On the tach, I am getting just about 4000 RPM's with full fuel and 2 people on board. Our engine had the valve guide issue's a few years back so I didn't dare add any more cup to the prop.

Anthony
"MadMoney"
Ilwaco/Seattle Washington

[RobS]

Matt,
Thanks for the info. Look forward to seeing what your prop scan specs are and I will probably await re-tuning mine until you have yours scanned.

Anthony,
Thanks for the info. I agree, seems yours is setup just right. Has your propped been scanned? - curious as to the "actual" pitch and cup specs.

[Anthony1013]

Rob -

I imagine it was scanned to get the proper balance and pitch however when I asked about the cupping, the guy's response was "the orginal prop had a medium cup". It seemed rather vague to me but when we bought our spare prop, I brought it into him to have him add a "medium cup" and he nailed it perfectly.

Anthony

[Cape Codder]

I'm running a 19x19 too. I just don't trust the Beede tachometer!
It would be helpful if along with the prop size and rpm's we all add the top speed in kts.
My top rpms read about 3700 and top speed is 24 kts
If everyone with 19x19's are running around 24 kts wide open, then I know the tach is off.
Thanks.

[RobS]

I have never looked at my speed at WOT, the only reason I ever push it to WOT is to check RPM's and Temp. Next time I'll note it.

[Jack28]

WOWZERS! 24 knts if I get 22 wot with the tide it is a lot. I think I have 19x19 will check when I haul. wot is 3900 on the yanmar tach at 3600 I do 17-18 with 3/4 fuel and water 3-4 pob's JACK

[RobS]

3-4 pob's JACK

3 to 4 Prisoner's on Board.....

Did you ever have that Yanmar tach checked for accuracy? They are notorius for being 150 over actual rpm's. Too bad they are not adjustable. Would be nice if they sold a "black box" type gadget that could go in-line with the tach sender wiring to the flywheel sensor that would allow adjustment of the tach.

[furball]

I have a 28 Flush Deck with the 6LP. I'm running a 19X18 LH prop. 3600rpm's and I'm at 18knts, WOT is around 21knts. My rpm's just make 3800 fully loaded, full fuel and water, fishing gear, dive gear, 2 people, 2 dogs, everything but the kitchen sink. This spring I think I was closer to 3900 WOT before everything got added. I had the the engine checked with a phototach during the survey and the Beede was very close. I found both tachs set for the wrong number of flywheel teeth, Beede off by 1 tooth and the Flowscan was off by 4 teeth. Both are now set at 117 teeth and are within 25rpm of each other. I hoped to add some pitch and pickup some speed earlier this year but now that the tachs are correct, I know I can't. I'm suprised at the number off 28's that have 19x19 props and still seem to turn 3800 or better. I'm wondering if it's a differance in the flush deck vs. the engine box setup. I plan to pull my prop this winter and have it scanned and tuned. Look forward learning something.
John

[RobS]

I'm suprised at the number off 28's that have 19x19 props and still seem to turn 3800 or better.John

John, Thanks for the feedback. Have you had your prop scanned? Cup is important with cruising speed, providing lift and an efficient, cavitation free, cut through the water. Cup will effect speed. H&H advised me that the "stock" prop should have been a 19x18, 5 cup.

The numbers do seem to fluctuate a bit btwn different 28's. I think the accuracy of the tachs is an issue. Also, just because a prop is stamped as a x18 or x19 does not mean that this represents the "actual" pitch as props can be tuned to add or remove an inch of pitch. Plus there is always the cup to consider too. So without a prop scan you really cannot be 100% sure of the prop specs.

[RobS]

I ended up having my 19x19 with 6 cup taken down to a 4 cup. The 19" Pitch was left unchanged. Cup was able to be done while I waited at the prop shop and at no charge because he did a recon the season before. By going down 2 on the cup I was able to gain the rpm's I needed and now turn 3900ish WOT. Any loss in speed was negligible.