Max prop on a saildrive

[levenezia]

I just ordered a new boat and opted for the saildrive instead of the standard shaft and prop. I did so because in this particular boat, with the standard propellor and shaft configuration, there is a hard pull to port due to location of the prop and rudder. The saildrive puts the prop that much further forward of the rudder and reduces prop wash. My question is, does the max prop work as well with this system as it does with the standard configuration? Would it be a worthwhile option over the folding prop that comes standard with the saildrive system on this boat? My main concern is straight tracking in reverse as I have a tight slip to back out of. (into) Larry

[Jeff_H]

Oddly enough saildrive systems generally have more prop walk than conventional systems. I would not expect better performance under power or sail with a max prop over a well designed folding prop except in that situation where you need stop the boat quickly by putting the boat in reverse. That said a max prop would have slightly worse performance when sailing.

Jeff

[SailorMitch]

The people I know with sail drives all talk about the LACK of propwalk, and how the boats back straight and true. In fact, they all give the sail drive very high marks for close maneuvering.

[Jeff_H]

I had a saildrive on my Laser 28 and thought there was a lot of prop walk for the size of the engine and prop. I had also experienced the same on a boat that I raced as well. Discussions that I have had seems to suggest that there is a bit more prop walk because if the vertical prop position but like other things in boating I can only assume that it is heavily dependent on the installation.

Jeff

[Jeff_H]

I had a saildrive on my Laser 28 and thought there was a lot of prop walk for the size of the engine and prop. I had also experienced the same on a boat that I raced as well. Discussions that I have had seems to suggest that there is a bit more prop walk because if the vertical prop position but like other things in boating I can only assume that it is heavily dependent on the installation.

Jeff

[Jeff_H]

[wwilson]

Actually, in forward the MaxProp provides about 96% of the efficiency of a fixed prop. The difference in drag under sail between the Max and folders is virtually inconsequential. In reverse the MaxProp provides much higher directional stability and efficiency than any folding propeller and approximately 80% of what a fixed prop would provide. If maximizing performance under sail and preserving backing power is your concern, the MaxProp is probably your best choice.

[Sailmc]

I have a 3 blade Maxprop and was told that it gave only 75% of the thrust of a 3 blade fixed prop in forward. Since it gives virtually the same thrust in reverse that it does in forward it give considerably more thrust in reverse than a fixed blade.

[wwilson]

sailmc,

Your MaxProp, for that matter almost any 3 blade feathering or folding prop, will deliver much better than 75% efficiency in forward (compared to an equivalent sized 3 blade fixed prop). The advantage of the Max is that it rotates its blades in reverse to turn its blade leading edges the most effective orientation for reverse. This actually increases its backing efficiency as much as 80% over that of a fixed prop. See this URL for the particulars.
http://www.max-prop.com/max-prop-in-pictures.html

[Sailmc]

The reason the Maxprop looses efficency is that the blades ar flat not cupped as on a fixed blade. They can''t be cupped because they must function in reverse. They give the same thrust in Fwd as reverse but you do loose due to blade shape.