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Old 17-05-2011, 10:05   #16
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Re: Boom Furl vs In-Mast Furl

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Originally Posted by doug86 View Post
Can someone explain this "too much weight aloft" argument against in-the-mast furling?
- leverage
- bigger mast
- windage
- extra water weight
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Old 17-05-2011, 10:26   #17
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Re: Boom Furl vs In-Mast Furl

Have had both systems, used them extensively..... 43' cutter with in mast rig custom made by Norseman, then a 52' cutter with Leisure furl boom.

Both are really useful if you are
1. singlehanding or have weak, old or useless crew
2. singlehanding with crew... in otherwords, standing single man watch at night

The furling option lets you adjust easily, and you tend to keep the sail area insync with the current weather conditions.

I like the boom option much more than the mast option; the boom sail has full battens and a much better shape, as well as a lot more roach to the sail. It is really bullet proof; you can always drop the sail and secure it around boom. The mast option has no battens, a much poorer sail shape and much less sail area without roach. If you have a problem, it can be a real hassle..... you have a sail up and no really good way to secure it if it is jammed.

Finally, the most important thing in either of these systems is having the right angle of the boom during furling and unfurling..... this prevents "bunching" in the mast or on the boom by keeping the same tension on both the foot and the leech edges of the sail.

Fair winds.
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Old 17-05-2011, 10:30   #18
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Like one of the threads said most opponents have never used one. I find then easy to use, efficient if the boat is designed for it. They do not jam unless poorly handled and need the usual
Maintenance that any mechanical device needs

As to weight aloft. All that's different is a slightly larger profile and some extra hardware. It's not a lot. A radar upsets the balance more.

Dave
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Old 17-05-2011, 10:39   #19
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Re: Boom Furl vs In-Mast Furl

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Originally Posted by doug86 View Post
Can someone explain this "too much weight aloft" argument against in-the-mast furling? I see comments that the weight adversely affects stability. But... but... most of the weight we are talking about is the sail, which is already aloft when the boat is under sail. How much extra weight can the furling gear add? 100#s? Certainly, no one is arguing that the weight of the furled sail is adversely affecting stability, are they?

The boat was designed to carry the weight of the sail up there, and the weight of the sail doesn't change whether it's flying open or furled.
You are correct that the weight of the sail is up there when it set and the boat deals with it without a problem.

The problem comes when the wind and waves get up a bit. With a normal slab reefing system the first thing you do is lower the sail and all the weight comes lower down - or to the bottom of the mast if you take it down completely - where it can do no harm.

With inmast reefing when you roll it the sail away the weight stays at exactly the same height on the mast which means that weight is acting on the end of maybe a 60ft mast. Multiply say 20lb of sail by 60 ft at the top of the mast and you get 1200 ft/lb of leverage acting on the hull. Then add the increasing weight of the rest of the sail at a lower height and you get a lot of ft/lbs trying to tip your catamaran over. It may not cause a problem but it could just make the difference between capsize or staying the right way up.
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Old 17-05-2011, 10:59   #20
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Re: Boom Furl vs In-Mast Furl

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Originally Posted by Bash View Post
the larger the boat, the more in-mast furling makes sense. Most production cruisers over 15 tons displacement are currently being designed with furling rigs, even on the high-end boats such as Oysters. While you can order boats with a "standard" rig, they are not under-canvassed with the rigs for which they are designed. Talk of "performance loss," therefore, is a bit naive with anything designed in the last decade. Such boats have got all the sail they need in normal conditions, and are readily able to shorten sail when the wind freshens up.
In the UK, at least (where there are some pretty ferociously keen sailors and really challenging conditions), cruising boats over 45 feet made in the last 10 to 15 years are almost never seen without furling mains. They are practically universal. I spent a lot of time at the Oyster facility in Ipswich a couple of years ago and never saw a big Oyster without a furling main other than one 1980's Oyster 55 ketch. Many of these Oysters had really expensive laminate sails, sometimes with vertical battens, but they always had furling mains. In support of what Bash said about big boats and Oysters and furling mains.

That doesn't prove that they are good, but to say that they are widely accepted is an understatement.

I don't quite agree with Bash that there is no performance loss. I think clearly it is harder to trim them perfectly, which means meaningful performance losses. But if the boat is designed for it, with a taller rig and more and/or deeper ballast, I think the performance loss is modest to barely noticeable. A bonus no one has mentioned is that the taller rigs are pretty -- the proportions are nice.

And as Bash mentioned, there is a concrete gain in performance to be had in many conditions from being able to instantly and exactly dial in the precise mainsail area you need for given conditions. Being able to always have precisely the right amount of mainsail out is a very big advantage.
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Old 17-05-2011, 11:10   #21
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Re: Boom Furl vs In-Mast Furl

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Originally Posted by Jeannius View Post
You are correct that the weight of the sail is up there when it set and the boat deals with it without a problem.

The problem comes when the wind and waves get up a bit. With a normal slab reefing system the first thing you do is lower the sail and all the weight comes lower down - or to the bottom of the mast if you take it down completely - where it can do no hasrm.

With inmast reefing when you roll it the sail away the weight stays at exactly the same height on the mast which means that weight is acting on the end of maybe a 60ft mast. Multiply say 20lb of sail by 60 ft at the top of the mast and you get 1200 ft/lb of leverage acting on the hull. Then add the increasing weight of the rest of the sail at a lower height and you get a lot of ft/lbs trying to tip your catamaran over. It may not cause a problem but it could just make the difference between capsize or staying the right way up.
This is undoubtedly true. And it's even worse than Jeannius says, because to make up for the lack of roach and subsequent loss of sail area, boats designed for in-mast furling tend to have taller masts. So you have more weight higher up, which is all bad. That's why you need a deeper and/or heavier keel to compensate, unless you are willing for your boat to be more tender and less stable.

Just to show how complicated boat design is: there is a tertiary effect of all this. That is -- aspect ratio. Taller rig and deeper fin keel will have higher aspect ratios, which increase their efficiency as airfoils or hydrofoils. That helps even more to close the performance gap with fully battened mainsail rigs.
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Old 17-05-2011, 11:19   #22
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Re: Boom Furl vs In-Mast Furl

Dockhead... If I sailed a mono I would have in mast furling. Absolutely no question about it.

However, the OP has a multihull, this thread is in the multihull forum. I think everyone who has posted in favour of in-mast in this thread sails a mono. You won't find many multihull sailors in favour of in-mast for the reasons I stated in my previous post.

Nice boat by the way... a Moody 54 was high on my wanted list before I converted to cats.
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Old 17-05-2011, 16:15   #23
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Re: Boom Furl vs In-Mast Furl

I agree with comments made by Jeannius, this is a multihull thread so comments should be based around multihulls. I have sailed on monohull yachts with both in boom and in ,ast reefing, but can say I have never seen a multihull with an in mast furling system.
With a cat or tri the idea is to get as much power as possible down low, be it racing or cruising and a mast system cannot provide these needs.
Myself, I prefer a slab reefing system, it works and a reef can be installed very quickly if all reefing lines are run in advance.

Peter
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Old 17-05-2011, 17:12   #24
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Re: Boom Furl vs In-Mast Furl

I have a Leisure Furl Boom installed on my Bristol 41.1. It takes a little tweaking to get the correct relationship of boom to mast angle, but once set I am very happy with it. Good sail shape, infinite reefing, and I don't have to leave the cockpit. An electric winch is neccessary for raising and lowering the sail. I had to wait a season for an Anderson winch, they were the only winch with a low profile motor at the time, and that season I was questioning if I did the right thing. It was the right thing to do.During our ten years of cruising, I have been at the mast in too much of a blow, reefing way after I should have, and it is not fun. As for maintainence, there is very little. It does add weight, but cruisers aren't racers, and I think cruising cats are more tolerant of weight than most people think. I am not sure, but I would imagine that the Leisure Furl could be sized for a main with a very large roach. In mast or behind mast won't allow for full battens. It was expensive, but when it comes time to sell, I think it will yield a partial return, or at least make my boat more desirable than others.
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Old 17-05-2011, 17:45   #25
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Re: Boom Furl vs In-Mast Furl

When people make the argument regarding weight aloft, it's not the weight of the sail they're referring to. It's the weight of the furling unit itself.
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Old 17-05-2011, 17:56   #26
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Re: Boom Furl vs In-Mast Furl

Watched a guy on a gazillion-dollar, high tech racy 45 footer spend all day trying to free his jammed up in-mast sail last summer. He finally had to call the manufacturer to come out. I'm sure these things are handy but the more complicated it gets, the more likely it is to break. If he was out in the middle of the ocean he'd have been F#%*ed.

I have one of those roller booms with a crank at the gooseneck that were popular in the 60s. Have never used it because I've read everywhere they don't really work that well and distort the sail. It's really just as easy to reef by flaking the sail down. Anyone out there who uses one of these successfully?
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Old 17-05-2011, 18:09   #27
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Re: Boom Furl vs In-Mast Furl

Spiritcat=but can say I have never seen a multihull with an in mast furling system.

I've never seen one in person either but there is a Privilege and a Catana for sale with in mast furling so they are out there. BOB
PS.I botched the quote deal
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Old 17-05-2011, 18:19   #28
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Re: Boom Furl vs In-Mast Furl

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Originally Posted by Jeannius View Post
However, the OP has a multihull, this thread is in the multihull forum. I think everyone who has posted in favour of in-mast in this thread sails a mono. You won't find many multihull sailors in favour of in-mast for the reasons I stated in my previous post.
Apologies; I didn't realize this thread was in the multihull forum. I accessed it through the general portal, and I seldom look to see where I'm trespassing.

It seems that cats, because of the way the stays stabilize the rig, tend to go with mainsails with significant roach--much more roach than you'd want to mess with on a mono with a conventional backstay. That being the case, a full-battened main would certainly be the call.
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Old 17-05-2011, 18:34   #29
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Re: Boom Furl vs In-Mast Furl

Cats or not cats, if other people browse this forum later, some of the issues will certainly be relevant.

Regarding weight aloft, one must also consider the added weight of water on rainy days. I am no physics professor, so I cant give any formulas, but the weight of several buckets of water up in the air is going to have an effect regardless one would think. Perhaps a smarter person than me may be able to figure out the changes to the righting moment.
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Old 17-05-2011, 23:16   #30
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Re: Boom Furl vs In-Mast Furl

Thanks guys, all in all it seems if in boom furls seems the better option for keeping the weight down, not that a cat cannot handle a inmast or behind mast furl but it certainly seems the in boom furl really have only one disadvantage and that would be relayed to reefing and the boom angle to the mast... this can be a bit of a teaser in strong winds maybe someone can come up with a simple yet effective way of speeding up the boom alignment issue.
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