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Old 16-07-2014, 12:24   #16
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Re: How does in-mast roller furling affect pointing ability?

My Jeanneau 379 had an in mast main. I could get it to tack through 75 degrees or so if I was really pinching it. Trading my genoa for a jib would have probably improved that a bit. Pointing high wasn't really a recipe for a great VMG in this boat though.
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Old 16-07-2014, 12:29   #17
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Re: How does in-mast roller furling affect pointing ability?

Other factors, like sail shape, design & trim, etc. will outweigh.

In any case, the loss (if any) will be marginal.

b.
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Old 16-07-2014, 12:44   #18
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Re: How does in-mast roller furling affect pointing ability?

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Originally Posted by Dockhead View Post
Remember that any boat will sail practically any angle to the wind -- if you don't care about speed. If you look at the polars on even quite hot race boats, the speed falls off a cliff below about 40 degrees true.

I have never been on a sailboat that would tack at maximum VMG to windward in less than 90 degrees, and that includes a 90' Swan with new laminate sails. I guess they exist, but I've never been on one. You can pinch any boat to something less than that, but why?
Fair enough. Most boats can be manipulated to point higher than is optimal, and for short distances it may be a reasonable tradeoff, like trying to squeeze around a mark instead of tacking twice. I was thinking of best vmg angle not highest possible.

While experimenting keep in mind that pointing the bow of the boat high has little to do with the angle traveled. At this point it is very possible to completely stall the keel, and be slipping sideways faster than you are sailing ahead.

When really trying to point high also take a page from Dennis Connor and drop the jib entirely. It is slow as all get out, but you will sail higher on just a main than the two combined.


I actually have sailed a few big boats (dinghys are weird and different) that could tack thru less than 90. But again it was a purpose built upwind racing boat with all sorts of weird controls to make it possible. Like running backs, jumper backs, windward shroud trims, hydrolic forstay rams, ect. It was also impossible to sail without at least six people onboard. Two just working the mast to keep it from falling down, since the mast extrusion was incredibly small.
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Old 16-07-2014, 12:45   #19
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Re: How does in-mast roller furling affect pointing ability?

[QUOTE=s/v Beth;1585791]
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Originally Posted by DoubleWhisky View Post
Just take Your COG on both tacks from Your GPS and You will have quite reliable tacking angle

Cheers

Tomasz[/QUOTE
Don't forget the current. I had my boat tacking @25 degrees until I figured in the tide
This was the reason I mentioned COG not heading, and wrote about "QUITE reliable"
With cross current the effect will be nearly balanced between the tacks.
OTOH the strong following current in light wind can do funny things

To the OP:

I was two time a part of boatyard organised regatta.
The boats were reasonably identical, but some had slab reefing, most in mast furling and only mine was with in mast furling and full vertical battens.

I was pointing as high as the boats with traditional mainsails (may be even touch better, but I had sails from really good sail loft), but being a touch slower upwind.
The boats with not battened roller mains were pointing a bit lower (not more than a 5 degrees difference) and were a bit slower than mine. Observations just for first legs after the start. I hope this help

Cheers

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Old 16-07-2014, 13:08   #20
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Re: How does in-mast roller furling affect pointing ability?

Still got ya Tomas: with a good current against the wind both tacks and sog showed 25 off the wind. Our current can be 6 kts dead upwind and ten miles wide...
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Old 16-07-2014, 13:31   #21
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Re: How does in-mast roller furling affect pointing ability?

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Still got ya Tomas: with a good current against the wind both tacks and sog showed 25 off the wind. Our current can be 6 kts dead upwind and ten miles wide...
Beautifuuuuul! You can go almost into the eye of the wind (over ground, of course)

The best pointing boat in the world You have

May be even better than one very famous Bene38...
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Old 16-07-2014, 13:39   #22
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Re: How does in-mast roller furling affect pointing ability?

That's what I thought too till l did the same thing with an adverse tide. Just telling ya that GPS can lie.
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Old 16-07-2014, 13:55   #23
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Re: How does in-mast roller furling affect pointing ability?

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That's what I thought too till l did the same thing with an adverse tide. Just telling ya that GPS can lie.
Being serious for the moment - I know the Valiants are rather well pointing boats, but for the 40 footer such a strong current on such wide area must be really difficult to go against...
Is it permanent, or tidal?
Just curious.
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Old 16-07-2014, 16:37   #24
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Re: How does in-mast roller furling affect pointing ability?

Wow - You guys have made this confusing and complicated.

Compass and boat speed...

I am amazed at the number of electronic sailors that can't even tell me how fast their boat is going.

Apparent wind, true wind, sog, cog, pointing & tacking angles - hocus pocus. The first question I always ask is, "What's your boat speed?"

The second question is, "Did you calibrate your speed log?"

If you can get past those two questions, let's talk about pointing. Biggest lie in sailing is pointing angle...
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Old 16-07-2014, 17:41   #25
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Re: How does in-mast roller furling affect pointing ability?

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Other factors, like sail shape, design & trim, etc. will outweigh.

In any case, the loss (if any) will be marginal.

b.
Agreed. The quality of the sails themselves are much more relevant than the method of reducing sail. On my first in-mast furling boat, I was amazed at the difference when I went from the OEM dacron main to a laminate, tri-radial main with vertical battens. I never got great sail shape out of the former sail, and rarely got bad shape out of the latter. That makes a huge difference when going to weather.
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Old 16-07-2014, 18:15   #26
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Re: How does in-mast roller furling affect pointing ability?

Tomas: the salish sea empties out through a big drain called the straits of Juan de F... every tide. The Columbia bank though not as wide can be more violent in places.
Tide is everything. More important than wind or destination. But we still manage to get there.
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Old 16-07-2014, 18:28   #27
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Re: How does in-mast roller furling affect pointing ability?

Dan, I agree. I just wanted to say what people were depending on can often deceive you. All I worry about is making the next landfall before the next storm. That and who is going to be on deck while I sleep.
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Old 16-07-2014, 19:18   #28
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Re: How does in-mast roller furling affect pointing ability?

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Beautifuuuuul! You can go almost into the eye of the wind (over ground, of course)

The best pointing boat in the world You have

May be even better than one very famous Bene38...
I've achieved an apparent tacking angle of about 10 on a Wharram cat.

Going through China Strait at peak flow in very light winds. Doing 8 knots SOG. COG was almost the same on both tacks.
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Old 18-07-2014, 17:34   #29
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Re: How does in-mast roller furling affect pointing ability?

I did some tacking yesterday and was able to maintain speed across 80 degrees to true wind by my instrumentation, without taking into account tides, currents, leeward motion of the boat, etc. Winds averaged 10..12 knots and boat speed consistently averaged about half of true wind while pointing. Below that, speed definitely fell off but the boat was able to maintain course down to 60 degrees true without luffing, but performance fell off down to less than 25% of true wind speed. Below that it was in irons.

So I would say its useful range is about 75 degrees, 70 if you're willing to take the performance hit or have higher winds than you need.

Sorry about the kerfuffle caused by not paying close attention to my instrumentation, and thanks for calling it out!

I'll hold off on reporting anything more accurate until I sort out exactly how to be more accurate.

Why is pointing ability reported as the sum of both tacks across the wind rather than the angle of a single tack?

Matt
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Old 18-07-2014, 17:58   #30
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Re: How does in-mast roller furling affect pointing ability?

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!


Why is pointing ability reported as the sum of both tacks across the wind rather than the angle of a single tack?

Matt
Many factors affect pointing - keel, hull, rudder, rig tune. Most boats will perform better on one or the other.

Knowing the angle on one tack may point out your favored tack.

But imagine a pure beat - Draw the rhumb line. In theory you hey diddle diddle zigzag up the middle and Machts nichts on time - knowing one angle is favored can help.

My boat does better on starboard - It is a science project to figure out why, and a nightmare to solve. I know I prefer to be on starboard but I also know that I have to tack through 90 degrees.

Current and sea state also come into play. Guys will report 15 degrees to true wind and VMG is blah, blah, blah - Great how about the other tack?

As I said before - boat performance is the biggest lie Skippers tell.
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