26m rotating mast

[mastreb]

The gain on my in a 12 knot wind is about one knot of performance as compared to fixing the rotation, as per my anemometer, on a beam reach. It's the difference between 4.5 knots at that windspeed and 5.5 knots. That's a 20% gain with no downside, which is generally pretty hard to find in vehicle efficiency.

The rotating mast on the Mac is actually what's called a Wing mast. It's aerodynamically shaped to act like the leading edge of a wing and to blend somewhat seamlessly into the thin foil of the sail. When it rotates correctly, the entire mast/sail system has a higher coefficient of lift than a sail fixed to a round mast or a non-rotating mast. The drag of the mast is considerably lower due to its shape, but it must be pointed to within 30% of the apparent wind to achieve that result.

Now, if you use slugs instead of a boltrope, you will lose a lot of that efficiency because the laminar flow doesn't transition smoothly. If you're going to use slugs, I wouldn't bother with an upgrade to a rotating mast.

I think it's great that comes with a rotating mast, but I personally would not bother with the upgrade, but rather plan on upgrading if you decide to replace your mast. It's a lot of work to swap out a mast, you'll want to change the sails as well, and then you're talking north of $3000.

Because as has been said, it's still a winnebago when you're done upgrading the mast.

To be quite honest, I was surprised by the test results, because it doesn't feel like as much difference as it actually is.

[kadet]

Now, if you use slugs instead of a boltrope, you will lose a lot of that efficiency because the laminar flow doesn't transition smoothly. If you're going to use slugs, I wouldn't bother with an upgrade to a rotating mast.

Must be my slugs that makes her a snail

[Ixneigh]

I had no idea that the slugs made that much of a difference. I may try removing them or gluing vinyl strips along the mast groove to act as fairings, or something.
Ix

[bscott]

I have the rotator on my 01 X and have mixed feelings about it:
THE BAD:
1) I don't remember the exact cost but it was north of $1,000.00 even with the dealer selling my take off, and me selling the X main and jib.
2) the M mast is 2' taller which requires a new main-you can still use your jib but mine needed to be replaced anyway. Since the sails act as a team I would not consider replacing only the main--kinda like replacing only one worn out tire on the car with one brand new one.
3) the taller mast is heavier construction and puts more weight aloft. Must reef sooner
4) main halyards need to be replace along with Harken swivel blocks at the mast base ($$$$)
5) engineering a dual back stay system to allow the mast to rotate is still work in process
6) the chain plates need to be moved OR the spreaders cut shorter-my choice
7) the rotation is not consistent and needs constant attention to get that extra fraction of a knot
THE GOOD:
1) looks like a real yacht
2) better light wind performance because the extra 2' reaches the early wind sooner-don't need a genny on a flukey high altitude lake.
3) better sails=much better pointing and performance
4) better sails with 2 reef point=less healing and better speed
5) faster than my dock mates stock X with old sails

If I had the chance to do it over again I would keep the stock mast and just replace the OEM Doyle sails with Judy's best advice and call it a day. And very happy with replacing the old Tohatsu 50 with the E-tec 60.

Bob

[Russ]

I had no idea that the slugs made that much of a difference. I may try removing them or gluing vinyl strips along the mast groove to act as fairings, or something.
Ix

In his book "Sailing Theory & Practice" professor C.A. Marchaj estimated about 2% loss of power from a mainsail separated from the mast on slugs. Prof Marchaj is widely recognised as the guru of everything aerodynamic and hydrodynamic about sailing boats.

See post about Winnebago. You can't turn it into a Corvette with a bolt rope. People will just laugh at you.

These discussions about performance are fruitless. High performance rudders, sails etc. It's a powersailor. The only real mod that might make a significant difference for the investment cost is a weighted keel and removing the water ballast. Make sure your rudders are parallel (many are not) and go out and enjoy the sea. We bought powersailors, not J-boats for a reason.

--Russ

[Russ]

I have the rotator on my 01 X and have mixed feelings about it:
THE BAD:
1) I don't remember the exact cost but it was north of $1,000.00 even with the dealer selling my take off, and me selling the X main and jib.
2) the M mast is 2' taller which requires a new main-you can still use your jib but mine needed to be replaced anyway. Since the sails act as a team I would not consider replacing only the main--kinda like replacing only one worn out tire on the car with one brand new one.
3) the taller mast is heavier construction and puts more weight aloft. Must reef sooner
4) main halyards need to be replace along with Harken swivel blocks at the mast base ($$$$)
5) engineering a dual back stay system to allow the mast to rotate is still work in process
6) the chain plates need to be moved OR the spreaders cut shorter-my choice
7) the rotation is not consistent and needs constant attention to get that extra fraction of a knot
THE GOOD:
1) looks like a real yacht
2) better light wind performance because the extra 2' reaches the early wind sooner-don't need a genny on a flukey high altitude lake.
3) better sails=much better pointing and performance
4) better sails with 2 reef point=less healing and better speed
5) faster than my dock mates stock X with old sails

If I had the chance to do it over again I would keep the stock mast and just replace the OEM Doyle sails with Judy's best advice and call it a day. And very happy with replacing the old Tohatsu 50 with the E-tec 60.

Bob

Great post regarding the cost vs. benefits from someone who's done it.

[fishheadbarandgrill]

Interesting analysis... couldn't help notice that none of the good are directly related to the pivoting mast. Seems you could just add a taller mast and you'd have the same outcome.

Bob

[Tomfoolery]

Interesting analysis... couldn't help notice that none of the good are directly related to the pivoting mast. Seems you could just add a taller mast and you'd have the same outcome.

Or better sails, which you'd have to do anyway. That's about all I'm willing to put into the rig. More than that, and I'd go for a speedy sailboat, not a motorsailor, and suffer the loss of the giant (for the boat's length) cabin.

[mastreb]

I had no idea that the slugs made that much of a difference. I may try removing them or gluing vinyl strips along the mast groove to act as fairings, or something.
Ix

In his book "Sailing Theory & Practice" professor C.A. Marchaj estimated about 2% loss of power from a mainsail separated from the mast on slugs. Prof Marchaj is widely recognised as the guru of everything aerodynamic and hydrodynamic about sailing boats.

--Russ

On a fixed mast, 2% is about right, but that's because the entire mast is interfering with the leading edge aerodynamics. On a rotating mast, the slugs vs. bolt-rope is a bit more important. Ferrier (of Trimaran fame) estimates it to be about 5% on a rotating mast. It's hard to tell whether Roger prefers bolt ropes because they're higher performance, lower maintenance, or lower cost, but my strong suspicion is that it's all three

I would still call 5% insignificant, but it is more important on a wing mast than a fixed mast.

[bscott]

Interesting analysis... couldn't help notice that none of the good are directly related to the pivoting mast. Seems you could just add a taller mast and you'd have the same outcome.

Bob

The rotator includes the swivel base and the swivel spreader attachment--other than that it is a relatively standard mast. There are higher quality light weight masts available for more $$$$$$$ that would probably be a better choice (I had one on my Capri 25--a very fast keel boat).

My X does very well sailing against a Catalina 25 w/standard masts on broad reaches and runs--however, they can out tack me on a close reach. I don't club race anymore but when 2 yachts approach each other then the fun begins especially with my very competitive grandkids crewing

Bob

[bscott]

I had no idea that the slugs made that much of a difference. I may try removing them or gluing vinyl strips along the mast groove to act as fairings, or something.
Ix

In his book "Sailing Theory & Practice" professor C.A. Marchaj estimated about 2% loss of power from a mainsail separated from the mast on slugs. Prof Marchaj is widely recognised as the guru of everything aerodynamic and hydrodynamic about sailing boats.

--Russ

On a fixed mast, 2% is about right, but that's because the entire mast is interfering with the leading edge aerodynamics. On a rotating mast, the slugs vs. bolt-rope is a bit more important. Ferrier (of Trimaran fame) estimates it to be about 5% on a rotating mast. It's hard to tell whether Roger prefers bolt ropes because they're higher performance, lower maintenance, or lower cost, but my strong suspicion is that it's all three

I would still call 5% insignificant, but it is more important on a wing mast than a fixed mast.

Agreed except it only matters with high quality racing sails, doubtful with OEM Doyles.

Bob

[mastreb]

Agreed except it only matters with high quality racing sails, doubtful with OEM Doyles.

Bob

True that. And I've not actually measured the loss with slugs, since I don't have them.

[mastreb]

Agreed except it only matters with high quality racing sails, doubtful with OEM Doyles.

Bob

True that. And I've not actually measured the loss with slugs, since I don't have them.