Importance of mast rotation

[mikelinmon]

Well, to open a can of worms; maybe rotation of the mast contributes up to 1/2 knot of speed like recently posted. Maybe more. I think most of the time, much more. Big picture is mast area is 15 sq-ft (6" times 30 feet). Un less rotated, It is turned sideways to the wind causing the boat to lean over and not giving lift or forward drive. First thing we noted on the first Mac with rotated mast was the lower heel angle, just our estimate, no measurement. The M was then designed to have 2' more mast than before. in light wind you have more drive, in high wind you have less heel. Any questions can be adressed to the by now many X owners with the rotating mast retro-fited. In general, they say " best add-on ever done". None I know of would switch back. Now as to the slugs, many have enjoyed the ease tof sail handling that slugs add, most state they are worth it. Few noted lower performance (although I am certain of it, that is just me). Most speed producers give such a small increase you can't measure it on a GPS. Try this; get someone to tighten all the way and ease/release the vang back and forth while keeping close watch on the GPS. I think you can feel much more change on rotation of the mast than mismanagement of the vang. A GPS will show the mast rotation! See, we had to decide whether to spend some Macgregor money on a very costly mast rotation based on pure performance. Not only that, we lost the backstay in the process. Roger really did not want to lose the backstay. Was tested for a year with no backstay and treated very rough with full standing gybes in high wind before the rotating mast got the go ahead. Notice the base of the mast has a tang which can and was used to control rotation. Tests indicate max rotation is needed upwind and even more downwind so the controls were not added. Good place to experiment on your own, let me know! Just grease the little washers under the mast once every tow years.
Mike Inmon

[c130king]

Does anyone have a photo of the washers Mike is referring to? A pic is worth 997.451 words (or so I am told).

Cheers,
Jim

[bscott]

What kind of grease and how do you access the washers? I have to run my shrouds a little looser than I'd like to get the mast to rotate in light winds. And yes, there is a performance plus to the rotation.

Bob

[TAM]

I have line run from the mast, past the stanchions, and back to the cockpit so I can rotate the mast manually in light winds. I can also force it to rotate in the wrong direction to de-power the main rather than reefing. I think others have done this mod also.



Terry

[magnetic]

Hi Terry

do you have any photos of these lines, or a description of the attachment points?

thx

A

[parrothead]

Photo of attachment point at mast [knot in control line creates a loop, so it can be connected to the shackle where the vang attaches at the base of the mast.


Photo showing the control lines leading aft through turning blocks [at the stanchion on the port side; using the dealer's original "halyard led aft" block that is stacked atop the daggerboard turning block on the starboard side].


Both control lines lead to clam cleats between the companionway and the winches, so the rotation position can be adjusted as desired and then "set"... handy for keeping the mast motionless when motoring or moored.

If curious about the "crossover" jib sheets, see mod explanation at http://www.macgregorsailors.com/modt/in ... ?view=1107

[Terry]

What kind of grease and how do you access the washers? I have to run my shrouds a little looser than I'd like to get the mast to rotate in light winds. And yes, there is a performance plus to the rotation.

Bob

Bob,
Your shrouds should be taught, not so tight to strum a chord, but tight, not loose, a well tuned rig will give you better performance. I used a Loos Guage to tighten mine and they are quite tight.
BWY has these little bearings you can buy for $20.00, but they are a wear out item that need replacing every couple years. They work quite well though and are worth the $$. My '03 M came with two white teflon washers about the diameter of the bottom of a coffee mug, I replaced them with the BWY bearing a copulpe years after I got the boat. (Istill have them) Some boats I have seen only have one teflon bearing. It is easy to remove the base plate on the mast bottom and replace the teflon washers.
I also have a couple lines rigged up for mast rotation control along with a 2:1 purchase pulleys. They run abeam from the mast at the vang attachment out to the stantion, around a pulley and back to the cockpit. They are a nice feature in light winds and are an easy to configure & install system.

[pokerrick1]

There is NO QUESTION for me that mast rotation ABSOLUTELY increases speed. I used to tack out of Marina Del Rey almost every day, and occasionally the mast would not rotate properly so I would rotate it manually (either with the boom or the line I attached to the base of the mast) and IMMEDIATELY - - -EVERY TIME - - - I could "feel" the surge of speed after it rotated.

If I were to rebuy a Mac, I would only buy an M with a rotating mast.

Rick Less

PS Whip me slap me I am starting to look at powerboats in the 21' to 26' range in which to be on the water in Lake Mead

[delevi]

I made some comments in the single line reefing thread on my personal tests with rotation.

The washers in question are at the mast base. To get to them, you must remove the bottom mast fitting (obviously when the mast is down.) Greasing them does help a lot. I would strongly caution anyone looking at the BWY ball bearing. I bought it and it lasted less than a month. It actually caused the mast to bind because the whole piece was crushed by rigging loads. The reason is the tiny diameter.. about the size of a penny which is all your mast is sitting on. The stock washers are a bit bigger, about the size of a quarter. I replaced the stock washers with ones more than twice the diameter and keep them greased once/year.

Leon

[Hardcrab]

As for grease, I use a white lithium based grease in a spray can.
I think I found it at an auto parts store.
This stuff does not make a big mess, and is water resistant/proof according to the can.
With the spray, a somewhat decent job can be had with the mast up.
Spray it on, work the mast around to distribute, repeat until it's worked it's way well into the washers, then clean up any excess overspray.

My grease effort seem to last about a year, but then again, I keep my mast up 24/7 in the storage lot.
If I lowered my mast to travel, I would respray every couple of trips just to be sure.

It makes a world of difference.

[dxg68]

I have stock washers and at first the mast didn’t rotate. Then I needed to adjust shrouds and lowered the mast by 10 – 15 degrees with mast raising system with boom and sails attached. I used white lithium based grease (actual grease not the spray) and little screwdriver and put the grease between each washer. It worked great the whole season even in light winds. Will do it again this year.

[delevi]

Spray didn't work too well for me, perhaps due to the high rig tension I prefer. Teflon grease is great stuff. Expensive, but worth it.

[dreamer]

I use Mclube Sailcote on the washers,very slippery and doesn't seem to attract dirt

[John McDonough]

First time I saw a M it was tied to the public dock at the pittsburgh Pirates stadium along the river. As I sailed along side I noticed the boat was not properly tied off,shaken loose by the wake from motorboats is always bad during events. Then I noticed the mast was flopping excessivly. I tied off to the M, and fixed the dock lines, but there was nothing i could do for the rigginng. I met the owner a few hours later. He had just bought the boat. I never saw him again. As a newbee to sailing, he just used it as a motorboat.

Can a 26X mast be modified to rotate. I would not want to change mast, but I suppose you could buy new rigging.

[Highlander]

I use Mclube Sailcote on the washers,very slippery and doesn't seem to attract dirt

I also use the same for mast base washer's mine are about the size of a siver dollar I will be changing them out for something a lot bigger this season as big as the mast base allows the bigger the washers the less pressure per sq. inch should turn easier !
i also use the sailkote on the mast slot and main sail slugs

J