18 mph under sail. Can it be done?

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delevi
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18 mph under sail. Can it be done?

Post by delevi »

On Friday, I took the afternoon off and took the boat out for what turned out to be a wonderful sail. Winds were between 18-20 knts. Sailing a broad reach, hit 10.5 mph a couple of times during gusts. This was with full main and jib. This got me thinking. What if I had the A-spin up? I know 20 knts really pushes the limit of the spinnaker and I certainly wouldn’t have attempted this while single-handing, but just how fast could a Mac :macm: go in 20 knts wind with full main and spinnaker? Considering I hit 10.5 with a 130 sq ft jib, 18 mph just may be attainable with a 350 sq ft spinnaker. Would be a lot of fun to prove Roger’s lofty claims. 8)
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baldbaby2000
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Post by baldbaby2000 »

I've hit about 9mph. I've heard of Mac 25s planing. An X might have a better shot at it with it's flat bottom.
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beene
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Post by beene »

I'd be worried the asym would blow out before you hit the magic number.

What little I have flown the kite, she doesn't seem very strong :?

G
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CFCassidy
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Post by CFCassidy »

You actually did about as good as you can do in a 20 kt wind with the wind behind you. As the boat accelerates, the apparent wind actually decreases in speed. The wind from your motion is opposite the true wind which is pushing you. Theoretically, these will balance out at 1/2 the true wind speed on a perfect downwind run.
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delevi
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Post by delevi »

I've heard of Mac 25s planing.
I planed out under sail on a few occasions. Around 9.5-10 mph is when the bow rises.
I'd be worried the asym would blow out before you hit the magic number.
That does concern me, but how exactly would a spinnaker blow out? If it blows out in the traditional sense, it may become too stretchy, which may not be so bad since it's a baggy downwind sail anyway. Of course, if it tears or completely looses its shape so that its functionality is ruined, that's not a good thing. I haven't had the kite up in anything more than 8-10 knts so I don't really know either. This is Scott's territory. I believe he flies the kite in some heavy stuff.
waternwaves
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Post by waternwaves »

I dont mean to rock the boat here........

but the only way I have found to approach those speeds.....

and I have gotten over 12mph now.....and I chickened out before the boat gave out... I still have too much on board to flip her, and I didnt have another guy my size to hike out.

both reefs in,

and the small hobie jib strapped on,

and a lot of surfing across the 3 ft waves, winds were 35-40 kts.

I should have have paid more attention to MadMikes journeys. This was the highest winds I have ever had rags out.

always more to learn I guess. ;) :? 8) :o
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baldbaby2000
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Post by baldbaby2000 »

and the small hobie jib strapped on
What kind of Hobie jib. I've used a Hobie 18 jib on my 25.
waternwaves
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Post by waternwaves »

I was told a standard jib, white...... , the guy had the hobie in the yard when I picked it up at a garage sail. there is what looks like a number 99201, and he was putting on a beautiful blue and green set of rags.

It is not very big. and not very strong. I would really like to get a staysail instead at 7 oz or so. But right now.....all x boat procurement has stopped for me until I figure out the additional navy purchases.

Even this little sail is too far forward in really heavy wind.

I would like to find the perfect winter jib. anyone else have any suggestions for a really heavy well shaped jib that is cheap??
eric3a

Post by eric3a »

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Last edited by eric3a on Tue Mar 11, 2008 12:28 am, edited 1 time in total.
Bill at BOATS 4 SAIL
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Post by Bill at BOATS 4 SAIL »

Has anyone tried a trapeze on a 26X or 26M?
I had a customer that used one on a 26C.
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beene
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Post by beene »

Yet another reason it surprises me you did not go with the older versions of the Mac :?:

You mentioned headroom, but still.....
waternwaves
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Post by waternwaves »

Eric,

I have looked into this......

and here is what I think, even tho others probably differ.

Being a fractional rig, I have er..... difficulty with the existing mast hardware which would be used for upper attaching. Since I want to swing forward of the mast, I am limited to a connection below the forestay, ,

I have a fair amount of bend in the bast, and at my weight the foretay looses, when I hike lard, I dont think the cabin top is compressing, so I am assuming that the mast is bending more.

I think if you are going to do that, you would want something stronger for a head attachemnt than the piddly through screws and bolting we have now.
waternwaves
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Post by waternwaves »

I like to think I sail gently, just in nasty conditions........... :?

But it seems I have broken a lot of stuff, pretty much everything I didn't figure on.

And tonight, try to fix a suspected leaky ballast fill valve...... (the alternative possible reason is not nice) God I hope I didnt crack something.
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beene
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Post by beene »

eric3a wrote:I'll sail the boat gently and learn it before I push and start breaking stuff.
When you get around to pushing your Mac to its limits, give me a call and I would gladly crew for you 8)

Better we break your boat then mine :D

Just kiddn'

.....but seriously, if you want a crew for some high wind experimenting, I'll fly down and join you anytime. :)

G
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delevi
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Post by delevi »

I beg to differ. I think the Mac with its planing hull can reach high speeds downwind. With racing sails and a weighted keel, I hit double digits (not knts) on a close reach, beam reach, and broad reach. Granted, I think the boat tops out around 10-11 mph on anything higher than a broad reach, since the wind velocity needed to go any faster would just overpower the boat. That being, said, I haven't had the new sails long enough to see what they can do in really high winds. I suspect I may break a few speed records (at least personal ones) in the spring and summer months when we get consistent 25-35 knts in the afternoon. I think with reefed sails, this baby will fly. Though I have broken numerous small things, I never felt that something was about to give, even when out in 40 knts. What gave was me... got wet, cold and a bit chicken, so I headed back.

Back to my original point. I doubt the 18 mph can be attained in really high winds. What I'm thinking is around 20 knts under spinnaker.

As for storm sails, I'll say it again. Use a furler and roller-reef the jib. I do this a lot and it works great, regardless of what some say about compromised sail shape etc. A luff pad and running backstays for the :macm: or the permanent backstay of the :macx: will help keep the jib's shape. When you need to reef it, its main purpose is just to balance the boat anyway, so shape isn't much of a factor.\

W&W, good luck with your ballast issue. Man, that's not a good problem to have. :?

Cheers,
Leon
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