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Old 06-07-2014, 12:24   #1
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How does in-mast roller furling affect pointing ability?

I don't have in-mast furling, nor do I plan to have it anytime soon (if ever). Just curious about this.
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Old 06-07-2014, 13:08   #2
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Re: How does in-mast roller furling affect pointing ability?

I plan on doing polars shortly on my instrumented Beneteau Oceanis 38 with stock in-mast roller furling. I'll post the results when I have them, if someone would like to post polars for the same boat with the standard mainsail.

The RF mainsail is about a 20% loss of power overall, losing about a knot of speed in the same winds compared to the standard main. But that shouldn't affect pointing, and may actually improve it because there should be less laminar detachment between the mast and the mainsail at the RF slot as compared to slugs. That's just a guess on my part however.
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Old 07-07-2014, 09:58   #3
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Re: How does in-mast roller furling affect pointing ability?

Quote:
Originally Posted by sneuman View Post
I don't have in-mast furling, nor do I plan to have it anytime soon (if ever). Just curious about this.
I cannot tell you what the polars are for my boat because I am still refitting her and she is lacking the instrumentation. But my Slocum 37 which is a modified Rafiki and similar to the Tayana has a housed after the mast Furlex system with Selden mast. I had my reservations concerning this set up but after tuning the rig the system although outdated performs. I estimate that she points within a 100 degree arc. Sail shape is remarkable considering she has a battenless main. When I get the money for a new main I will go for vertical battens.

As you get older, having everything lead into the cockpit is not only a convenience but a great safety feature. Btw both my head sails have Pro-Furls and it can't get any easier. Particularly when my son's are pulling all the lines.

Regard,
BZT
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Old 15-07-2014, 23:46   #4
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Re: How does in-mast roller furling affect pointing ability?

So I was taking good note of the wind direction while sailing, and I have to say the RF furling is almost certainly no issue with my Beneteau 38. It's easily pointing to 30 degrees off true, which is better than I'd expect from any main.
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Old 16-07-2014, 00:18   #5
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Re: How does in-mast roller furling affect pointing ability?

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Originally Posted by mstrebe View Post
So I was taking good note of the wind direction while sailing, and I have to say the RF furling is almost certainly no issue with my Beneteau 38. It's easily pointing to 30 degrees off true, which is better than I'd expect from any main.
Another astonishing performance reported for this phenomenal boat. It would be a crime to not race it, for your various reports indicate that it outperforms race boats of her size. A few races and either your competitors would be buying B-38s or you might be re-evaluating your impressions.

Tacking within 60 degrees, as you seem to think you can easily do, is better than all but a very few dedicated racers can do. If actually true, I'm deeply impressed, but I remain skeptical. As I say, a few races could dispel my skepticisim.

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Old 16-07-2014, 01:02   #6
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Re: How does in-mast roller furling affect pointing ability?

To be frank, I'm skeptical of the wind instrument. The masthead vane is closer of course because it reports apparent wind, but as I rotate the boat around the true wind varies by more than the feel of it tells. I think I'll have to calibrate this new boat's sensors before I make firm statements.

But what will say is she makes 6 knots in 9 knots of true wind while pointing, and 2 knots in 3 knots on a broad reaching the stock jib and mainsail. I'm happy!


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Old 16-07-2014, 01:05   #7
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Re: How does in-mast roller furling affect pointing ability?

Jim,
I' know I would like you as a person, you are very kind. Our friend with the B38 is obviously a newby with his many claims that share space with religious fanatics.
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Old 16-07-2014, 01:10   #8
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Re: How does in-mast roller furling affect pointing ability?

Robert, I'm sailing the boat daily right now, and quite happy to run video of the instruments reporting the boat's speed, heading, and true wind as I sail through San Diego Bay. New to this boat and forum, yes. New to sailing, no.


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Old 16-07-2014, 09:06   #9
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Re: How does in-mast roller furling affect pointing ability?

Quote:
Originally Posted by mstrebe View Post
Robert, I'm sailing the boat daily right now, and quite happy to run video of the instruments reporting the boat's speed, heading, and true wind as I sail through San Diego Bay. New to this boat and forum, yes. New to sailing, no.


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I appreciate that you are reporting what the instruments say, but your instruments are wrong. The number of boats that reliably tack thru 60 degrees true is vanishingly small. This would be right there with the AC 90's which had an ideal tacking angle of 19 degrees apparent or about 60 degrees true. But the B-38 is in no way optimized for upwind ability. Theta angles are too big, keel is the wrong shape, even the mast is all wrong to be playing at these fine tacking angles.

Other than the AC90's a very good pointing boat like a OD35 may have a target of 35-40 degrees but these are purpose build upwind machines. For a cruising boat to approach these angles means that either the instruments are wrong, or they are being used incorrectly.

As for 6kn in 9kn true... Possibly, but at the very high end of what I would expect. More likely a peak speed than an average.


Back to the OP. Generally I would guess 5-7 degrees is the trade off, but it is hugely dependent on what boat you do this too. A massive roach catamaran for instance may loose much more, while an IOR optimized boat with a small main and massive jib it may not effect nearly as much.
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Old 16-07-2014, 09:21   #10
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Re: How does in-mast roller furling affect pointing ability?

Our previous boat had other performance issues besides the roller furling in the main mast, but some of the performance issues were undoubtably due to the roller furling. No battens, less than optimal sail cut, etc. We loved it though as we could reef in almost any conditions from the cockpit. There were times we probably should not have. We consistently would either bring out the main and reef without going in to the wind. It took some hard winching sometimes and I always wondered if it would break things but it never happened. I also suspect it was easier on the sail because it did not flog. It certainly was safer for us in challenging conditions.

We now have a traditional rig and I am learning to uphaul and reef the main. This boat tacks so much better it is like comparing a fighter jet to a paper airplane. I may grow to love the difference but I will miss the roller furling in bad weather.

Having said all that, the system used is very important. Some of them can jamb at times which could be a real problem. Our mizzen furler was a different design and it jambed so much, even in light air, that I basically quit using it. The new owners solved that by removing the mizzen altogether. Kind of extreme.
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Old 16-07-2014, 09:40   #11
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Re: How does in-mast roller furling affect pointing ability?

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Originally Posted by mstrebe View Post
Robert, I'm sailing the boat daily right now, and quite happy to run video of the instruments reporting the boat's speed, heading, and true wind as I sail through San Diego Bay. New to this boat and forum, yes. New to sailing, no.


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Just take Your COG on both tacks from Your GPS and You will have quite reliable tacking angle

Cheers

Tomasz
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Old 16-07-2014, 10:19   #12
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Re: How does in-mast roller furling affect pointing ability?

[QUOTE=DoubleWhisky;1585751]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
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Old 16-07-2014, 11:17   #13
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Re: How does in-mast roller furling affect pointing ability?

Quote:
Originally Posted by Stumble View Post
I appreciate that you are reporting what the instruments say, but your instruments are wrong. The number of boats that reliably tack thru 60 degrees true is vanishingly small. This would be right there with the AC 90's which had an ideal tacking angle of 19 degrees apparent or about 60 degrees true. But the B-38 is in no way optimized for upwind ability. Theta angles are too big, keel is the wrong shape, even the mast is all wrong to be playing at these fine tacking angles.

Other than the AC90's a very good pointing boat like a OD35 may have a target of 35-40 degrees but these are purpose build upwind machines. For a cruising boat to approach these angles means that either the instruments are wrong, or they are being used incorrectly.

As for 6kn in 9kn true... Possibly, but at the very high end of what I would expect. More likely a peak speed than an average.


Back to the OP. Generally I would guess 5-7 degrees is the trade off, but it is hugely dependent on what boat you do this too. A massive roach catamaran for instance may loose much more, while an IOR optimized boat with a small main and massive jib it may not effect nearly as much.
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?
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Old 16-07-2014, 11:23   #14
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Re: How does in-mast roller furling affect pointing ability?

what about the same question for free standing roller furled, loose footed main?
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Old 16-07-2014, 11:28   #15
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Re: How does in-mast roller furling affect pointing ability?

I won't even try to get into technicalities such as polars, but I ended up on a Hunter for 7 years for a variety of reasons, and I was skeptical and (for a long time) concerned about how the negative roach and low aspect of the in-mast main would affect pointing. I never ceased being surprised at how well it pointed, I would say that it pointed as well as any other comparable boat that I have sailed, roughly 30o off the apparent wind in moderate conditions. Perhaps it was the hull design, mast placement, I don't know, but I can say that I no longer systematically conclude that a boat with in-mast furling will not point well, they can for sure. pete
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