Before I splashed my 26C this season, I had a 2-blade MaxProp
installed. Used the MaxProp recommended settings for my W-21, 2:1
transmission. Prop makes the boat go forward and backward, when
asked...no complaints.
However, since I do not have experience with any other prop, I have no
point of comparison. Maybe it's over or under pitched. How do I
determine if the current setting is optimal or if it should be tweaked
when the boat is hauled next month? I figure there must be some on
the water test for this.
I, also, Have a Max prop. Performs with no complaints. Put the sail up
(electric Lewmar 40 winch) get under way, shift to neutral. Prop feathers,
shut down diesel. A great prop. Bob Horne. N26C, 1989 #249, Encore,
Pocasset, MA.
Bob,
My boat, formerly known as "Cat Nap", used to live just down the road from you in Green Harbor (Marshfield), MA. I don't have an electric winch, but I do have the Tides Strong Track installed. Sail goes up easily for most of the way...I just use the winch for the last few feet.
Regards,
Jim
With no wind, no seas, engine warmed up , throttle up to max.
At this point, max RPM should reach engine rated max RPM.
If it doesn't, you have too much pitch. You will be causing the engine to "LUG".
If it is exceeded, you have too little pitch. Problem here is governor on injection pump
may prematurely limit RPM. Check manual and with engine manufacturer.
Some engines have a short term max RPM rating and a continuous RPM rating.
Use the Max figure to be safe.
I agree w Allen completely. When I checked mine I had a hard time finding the max rec RPM for my W 27A, though. I think I had to talk w someone from Westerbeke, or a distributor, to get THE REC 3000. But once you have the number and you just manage to get to that RPM, then you should have it right. You should get good boat speed running at 75-80 % of the max, which is also recommended. Joe Valinoti can and will answer the engine questions best.
Bob Horne mentioned about shifting to neutral and then shutting down the diesel. I believe I was told the opposite - shut down then shift to neutral. More likely to force the prop to feather. Could others jump in on this point?
Fred Rachwitz
NS 30 U 445
Concerto
Harbor Springs, MI
The Max-Prop Manual at page 8 states:
"The Max-Prop works automatically. By putting the engine in gear the
blades will engage in either forward or reverse.
The best way yo feather the propeller is:
--- Power at 2 to 3 knots in forward.
--- Kill the engine while still engaged in forward.
--- When the engine is stopped, if the shaft is still spinning engage
the transmission in reverse to stop the freewheeling.
You can check to see if the propeller is feathered or not by taking
the engine out of gear. IF the propeller is not feathered the shaft
will freewheel like with a fixed blade propeller. In that case start
the engine again and repeat the three steps. If your propeller has
been greased properly it will feather in a fraction of a second as
soon as you stop the shaft from freewheeling.
Once the prop is feathered, you can either leave the transmission in
gear or out of gear, it does not matter.
Do not kill the engine while in reverse. In this case the blades will
be in the reverse position and will not feather. You can actually use
this feature to drove a shaft alternator."
In summary, have the boat in gear and the engine running. Then kill
the engine. You can leave the transmission in or out of gear.
Mark Powers and Nesta Davies (M&N)
La Reina 26C
Burrard Civic Marina
Vancouver B.C.
There is usually a metal plate on the engine which gives the model number, serial number and the horsepower at a specified rpm. With a clean bottom, you should be able to reach that rpm in flat water after the engine is warmed up. If you can go above that rpm, you have too little pitch. If you can't get to that rpm, then you have too much pitch. Diameter also effects this, but it is clearest to think only in terms of pitch.
I can get to about 2950 rpm after splashing in the Spring with my Universal M-35 (30 hp) but I should get to 3200 (I think). When I had my MaxProp remanufactured last Winter (half the cost of a new one after 18 years of service), I asked them about changing the setting. I don't recall the exact numbers, but they said changing one letter up or down would change it by maybe 400 rpm, and that was too much. So the recommendation was to leave it alone.
A prop shop can change both the diameter and pitch of a solid bronze non-feathering prop pretty easily and exactly...I did that on my last boat. But the MaxProp with its mechanical adjustment is not that precise. Nevertheless, I would not trade my MaxProp for any amount of money.
A friend of mine installed a new MaxProp last Winter on a 38' sloop, and in September he hit what was probably a submerged log or a stump on the Bay. His shaft was bent; when they went to straighten it they discovered it was also twisted so that the keyways did not line up, and it had to be replaced. His MaxProp was undamaged. Hartge's Alex Schlegel (the Gold Standard for honest competence in this area) told him it must have hit the tip of the blade to twist the shaft like that. That's a pretty good recommendation for MaxProp, I think.