Sail servos for "sail areas" ?

Somewhere, a long time ago,…and probably in a far off land :wink: I think (???) I recall a table of sail winch comparisons - and it also had a secondary table of average or recommended servo torque ratings for various sail areas. It didn’t factor in the type of boat/hull - or wind conditions, just recall it being something to the effect that … for “X” square inches of sail, look for a servo providing “Y” minimum torque.

for 1100 sq. inches SA - RMG280 or Hitec 815BB (or something like that)

Is there something out there - or perhaps I’m just dreaming (from too much acetone fumes) :smiley:

Any help greatly appreciated. Thanks in advance.

as a second thought, I can list the general sail areas, and suggested/recommended torque (or winches) listed…

below 300 sq. inches
300 sq. inches to 600 sq. inches
601 sq. inches to 800 sq. inches
801 sq. inches to 1100 sq. inches
1101 sq. inches to 1400 sq. inches
>1401 sq. inches

Will also post at a couple of other sites - sorry for duplication.


What about pulleys and such?

Adding pulleys to a sailwinch arm changes the torque so you probably can’t compare things straight up, unless you first specify the sailwinch arrangement, like a double arm with brass eyelets or single pulley/single purchase setup.

Tomo -
I understand that, but then we go down the road of on-going “what-ifs”…

If using your suggestion, then we start to play with arm movement or number of turns for a drum “what-if”.

Not saying it isn’t important, but “usually” the ratio is 2:1 for most boat set-ups and then length of arm movement will need to be used to calculate the length of mainsheet possibly moved, which then suggests a drum winch of 2 inches diameter can haul “X” inches of line, but increasing diameter slightly will provide “X+Y” amount of line, but then it will reduce the strength of the servo depending on the arm and so on and so on… I think you see my point.

I was hoping more for a few boat designs to follow the listed sail areas - given those are actually being used (or replaced) … I can also use a few of mine, but found my Hitec selected for my RG-65 was considered “overkill” by some, so there is another tangent to consider - or muddy the waters.

Perhaps, folks can simply post the boat, the advertised (or actual) sail area and the winch they are using. Let’s not worry about “over-kill” for the first pass on this basic data.

Something like:
1 meter multihull - 1100 sq. in. - Hitec 815BB (arm)
IOM monohull -
US1M monohull - 600 sq. in. - ???
RG-65 monohull - 300+ sq. in. - Hitec HS-645MG (considered overkill)
F-48 multihull - 1400 sq. in. - RMG 380
65M - multihull - 300+ sq. in. - GWS-1T (swing rig)


If you want - you can PM me and I’ll consolidate into a reference chart if there is enough cooperative interest.

What are they using in the Laser now? … in the Nirvanna (factory vs. custom), ETNZ (stock & custom), CR-914, ODOM, etc.

Having a standardized winch setup allows you to directly compare how the servos work. You could add some rules to allow noobs to get an idea of how much (sort of) to increase or decrease the rating, but since you cannot quantify that stuff, put in a disclaimer. :scared:

Hi Dick,

I tripped over this servo database (650 servo’s) which compares torque etc. unfortunately does not give torque rating for various sail areas, love to find that info as well.

Cheers K1


K-1 —thank you. That is one I had not seen before - and I may have to amend for US measurements.

Rusty — you hit it, and it is now saved to my favorites. That was the one I had seen and “thought” I had saved. Excellent reference material

Thanks to both of you for posting. I’m sure this will be helpful to others.