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Re: 18 mph under sail. Can it be done?

Posted: Mon Mar 01, 2021 6:54 am
by seaskipr
I can confirm the forestay plate sliced aft about 1.5cm on my mac 26X, when the jib let go in a 50. The flogging action pulled the plate aft, loosened the rig and I guess then pulled further back. I can send a pic. My question is, how to get access inside the bow to fix etc.

Kind regards, Tony

Re: 18 mph under sail. Can it be done?

Posted: Mon Mar 01, 2021 9:19 am
by rsvpasap
So this is what it looks like on the underside of my 26X bow, showing the holes for the BWY bow roller I previously installed and removed, the bolts for current larger bow roller, the bolts for the cleats and the steel forestay attachment strap inside the bow. Access requires some contortionist skills.
Image

Re: 18 mph under sail. Can it be done?

Posted: Thu Mar 04, 2021 11:41 am
by Ixneigh
Hmmm. Well I read the whole thread here. A few thoughts;

Planing is skimming on top of the water for long periods. Not just surfing down a wave.

I don’t think the m/x has the stability under sail to do it. And if it does, it doesn’t have the rudders to do it. All those planing race boats are wide in the stern. No narrow nellies. The m/x are narrow. The rudders are the wrong size (too big) to operate at that speed. It’s why the manual tells you to raise them powering over six knots. The rudders are an effective size for average sailing conditions. At speeds above say 8 knots, they will either oversteer the boat, or contribute to roll and possible broach. Same way with the M daggerboard. So above a certain speed you can’t have the M dagger down else it acts like a wing to roll the boat over. Re: the warning to NOT motor over a certain speed with it down.
The downwind conditions I had my M in, I could hit about 6.5 knots. Maybe 7 for a moment. (Surfing) the boat was extremely difficult to control and rounded up uncontrollable a few times. It was almost impossible to get her pointed down wind again. ANY amount of dagger board down will contribute to instability, but you need something for control against broach. Maybe the X would do better with her center board, I don’t know. I installed runners to feel comfortable pushing the boat harder downwind. I’ve been out in winds strong enough to render the boat almost unsailable with only a double reef main. If you can get her off the wind and keep her there you aren’t going to plane. You just are not going to do that with these boats I don’t believe, in any circumstances. At 8-9 knots, she’s in semi plane mode. It takes a lot MORE energy to get her to full plane. The hull and rig can’t provide it.
Maybe, with no ballast, no gear, and several people on the rails, you might do like those beach cat sailors did. But that’s a stunt. Not something the usual owner could do.

Ix

Re: 18 mph under sail. Can it be done?

Posted: Mon Mar 08, 2021 2:08 pm
by sailbert
Comment regarding the rudders.
Never sailed my X yet, but I can tell you that the rudder of a F-27 Tri is way larger (too large compared to modern designs) and does stand 15kn++
Seeing the X on the dry now, it is more the mounting that will go in pieces, it's just very tiny and fragile.
Don't get me wrong, no compaining here...
Proven and suitable for everything the boat is designed for, not less, and most likely not more

Re: 18 mph under sail. Can it be done?

Posted: Tue Mar 09, 2021 5:44 am
by Inquisitor
Ixneigh wrote: Thu Mar 04, 2021 11:41 am ...
Maybe, with no ballast, no gear, and several people on the rails, you might do like those beach cat sailors did. But that’s a stunt. Not something the usual owner could do.
Ix
Obviously, this falls in the, "don't do this at home category". A buddy and I were competing in a race down in Florida. It was a large fleet, but there were only four other Mac X and M's and about dozen total in our Perf class. They start the boats on a slowest first with the idea that you all hit the finish line at the same time. The winds were far lighter than we had hoped for, but we had a tail wind for the first leg of the race. Before our slated start time, I used a 12v transfer pump to drain the ballast via the vent hole. We did pretty good on hitting the start line at full speed with the Asym pulling. 8) We were clearly faster than the others in our class, but with the light winds, that still was only 7 knots. The boat felt surprisingly stable. I want to recall that we had nearly thirty minutes on this heading and there was a large ten minute sweeper next into a beam reach. Of course, we were feeling cocky having a sizable lead and stretched keeping the Asym up to long. With full ballast, we'd always kept it up in a beam reach... not so without ballast. Of course we smacked the water with the mast. We were prepared and actually enjoying the experience. It turned into the wind and popped right back up. We lowered the Asym and opened the ballast tank. :(

Point being... IMO, I doubt at even the max wind the Asym can tolerate AND without ballast, we'd have gotten to 10 knots sustained. That getting on plane power requirement is just way higher than can be supplied by wind.

Maybe, some more rocket science is called for...
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Re: 18 mph under sail. Can it be done?

Posted: Tue Mar 09, 2021 8:55 am
by Be Free
Inquisitor wrote: Tue Mar 09, 2021 5:44 am Obviously, this falls in the, "don't do this at home category". A buddy and I were competing in a race down in Florida....
Mug Race?

Re: 18 mph under sail. Can it be done?

Posted: Tue Mar 09, 2021 9:04 am
by Inquisitor
Be Free wrote: Tue Mar 09, 2021 8:55 am
Inquisitor wrote: Tue Mar 09, 2021 5:44 am Obviously, this falls in the, "don't do this at home category". A buddy and I were competing in a race down in Florida....
Mug Race?
You got it!

Re: 18 mph under sail. Can it be done?

Posted: Thu Mar 11, 2021 7:11 am
by Ixneigh
Re farrier tri rudder size

it has something that the m/x does not. Width. (Stability)
A few pages ago someone posted about uncontrolled rounding up at above hull speeds. This has been my experience. One of the causes of this is rudder lift. This is an issue on the m at least, due to low form stability, rudder shape and position. Off the wind, you can ignore lack of righting moment long enough to reach a point where the steering becomes very squirrly, just like that poster described. Having just the right amount of board down will help a little, but at a certain speed, the rudders start to contribute to rolling due to lift, and the boat rounds up. It’s a feature, not a bug. It keeps people from exceeding the boats rigging and sail capabilities. You actually can’t break anything on the stock boat just under sail unless you maybe do an uncontrolled gybe and tear the main on the spreader tip. The Boat is what she is. The mods I’ve done to mine haven’t been in a quest for more speed, but rather more control when the boat is sailing in the 5 plus knot range. Specifically reducing loads on rudders, hardware and steering gear.

Oh yea, so say you actually do get the boat to 10 knots under sail, downwind. One wad of seaweed on the rudders will end it with a spectacular broach 😂😂😂

Ix