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yeller
06-24-2015, 03:34 PM
This may be a dumb question, but how do you determine where "straight up" and "straight down" is when clocking the props?
I have the documentation showing the clocking procedure, but what is not clear to me is, what part of the prop do you look at when determining the up/down positions.
If you take it from the base of the props, you get wildly different positions than if you take it from the tip of the props. The same holds true if you take the up/down positions from the front, centre, or rear of the props.
I have mine clocked so they appear to be the same as in the clocking diagram, but I have what I feel is excessive vibration. Of course I can move it one spline left and right to test, but I'd prefer to get it right before I put the boat back in the water and avoid the testing.

yeller
06-24-2015, 03:54 PM
Looking at the diagram, it appears the front prop is set with the tip straight up and the back prop is set with the middle of the base set at straight down. Is that correct?

Morgan's Cloud
06-24-2015, 05:18 PM
That's actually how I set up the props on my B3 and DPS-A but as nice as it looks they only ever re-align at that exact position after x number of rotations .
But , still we do it .

yeller
06-25-2015, 04:41 PM
Thanks MC. From my understanding, a "submerged" dual prop doesn't need clocking. I'm sure it doesn't hurt though.
The BH has to be clocked because the props break the surface and need to be timed in order to properly feed the back prop.

Ghost
06-25-2015, 05:14 PM
Volvo specifies that duo props should be clocked such that the blades are NOT overlapping when in the 12 o'clock position. My understanding is that this is so that they don't cross while under the plate, which I suppose would add to the interference that passing the plate causes.

mattyboy
06-26-2015, 07:29 AM
I think all counter rotating props needs to be clocked someone moved the outer prop on my nephews B3 setup it was off it had a bit of a vibration and it lost some top end. the easiest way to picture it on a 3 blade prop is 2 Y's the first one upside down so the bottom of the Y is at 12 o'clock and the other 2 ends point at 4 and 8 then the 2nd Y right side up with points at 10 and 2 with the bottom at 6.

that pic looks off due to the round blade on a sharp clever like the BH props it is easier to see.

BUIZILLA
06-26-2015, 09:38 AM
that picture, as drawn, is not correct..

Morgan's Cloud
06-26-2015, 10:39 AM
that picture, as drawn, is not correct..

Not sure how precise and exact the diagram really is , or whether it's a case of 'this is kind of what they should look like'

How do you do the props on your Baby 16 ?

BUIZILLA
06-26-2015, 02:05 PM
Not sure how precise and exact the diagram really is , or whether it's a case of 'this is kind of what they should look like'

How do you do the props on your Baby 16 ? the Yammi works differently and doesn't lock in unison on the driveshafts, in fact, in reverse, only the front prop locks in and the rear prop spins free.... on my B3 in my Formula I used the trailing straight edge of the blades and clocked them that way, if your off as much as 2 teeth you can feel the vibration in the hull...

yeller
06-26-2015, 04:05 PM
that picture, as drawn, is not correct..it's certainly confusing. The BH has a round ear in front and a clever in the back so I need a specific point on both props to determine straight up/down.
Just got a PM from a Cig 20 owner that said he'll send pics of his setup, so I should have an answer soon

craigdskilling
06-27-2015, 08:34 AM
I set mine at front prop cutting edge of the blade at 12:00 and the back of the cutting edge of the prop at 4:00 works for me can't wait to see what you heard.:)

younger
06-27-2015, 11:38 AM
The front prop loads the rear, so phazing the props is critical. On the 16 I played with this for some time and when its right there was no vibs. My props were Hoss cleavers so I referenced off the rear strait edge of the props. With the front at 12, and made the adjustment on the rear one spline at a time till it was golden. What happens when the props are out of phaze, the front prop pushes water into the rear prop blade causing your vibration.

Morgan's Cloud
06-27-2015, 12:35 PM
the Yammi works differently and doesn't lock in unison on the driveshafts, in fact, in reverse, only the front prop locks in and the rear prop spins free.... on my B3 in my Formula I used the trailing straight edge of the blades and clocked them that way, if your off as much as 2 teeth you can feel the vibration in the hull...

That's interesting about the Yammy . So you can't time them at all ?

While we're at it , I've never driven anyone else' s B3 but out of curiosity can you tell me what happens with your Formula when you're running at speed and you over trim ?
And also , do you find that it has less +trim range than what you'd expect compared to a B1 ?

Morgan's Cloud
06-27-2015, 03:10 PM
The front prop loads the rear, so phazing the props is critical. On the 16 I played with this for some time and when its right there was no vibs. My props were Hoss cleavers so I referenced off the rear strait edge of the props. With the front at 12, and made the adjustment on the rear one spline at a time till it was golden. What happens when the props are out of phaze, the front prop pushes water into the rear prop blade causing your vibration.

While , at first blush , this makes perfect sense the thing is that for 50% of every single rotation the props are positioned with one blade directly behind (or in front of ) the other.

yeller
06-27-2015, 05:07 PM
Thanks guys. I got a pic and a video from the Cig owner but I need to still call him for clarification, which I can't do for a couple of days.
While , at first blush , this makes perfect sense the thing is that for 50% of every single rotation the props are positioned with one blade directly behind (or in front of ) the other.
Good point MC but I think it's critical on the BH where that happens because the props are not fully submerged.

MOP
06-30-2015, 08:02 PM
Well worth the time clocking, I had slight but noticeable vibration, the picture and write below smoothed thing out.