'On-Boom' furling systems do exist. I had one on my last boat.
It is very, very simple, and works really well.
All that is needed is a hole in the mast where the gooseneck is. This hole is sheathed with a stainless molded plate either side to take the boom fitting, which is just an extended pin around ten millimetres thick. The pin goes all the way through the mast, with about 25 millimetres (an inch) sticking out the other side. Onto that is fitted a truning handle with a grub screw-type arrangement for gripping the shaft. There is another hole in the mast corresponding with the other end of the handle so that when the sail is in the required position, the axle of the handle can be pushed through this hole to lock the whole device.
It is simply necessary then to allow the fitting where the mainsheet connects to the boom to swivel freely. Of course, the system can only be applied to boats with end-boom sheeting. This all works perfectly with fully battenned, loose-footed mains. The benefits in reefing are terrific as all you have to do is have someone stationed at the mast, ease up and luff the boat, release the halyard, wind in some sail (or all of it, if taking down), re-tension the halyard, and come back on the breeze. The main should be designed with a reinforced leech for longeitvity, but this aint critical.
The one that was on my old boat was made by the people who built the mast, but the same could be easily fabricated by a handyman.
Mainsail Furling/Reefing System by CDI
Lease,
With the system you describe, you couldn't use a boom vang and I've not yet seen an X or M that was sheeted at the end of the boom.
But, what wtelliott is describing is (I think) taking a roller further system and mounting it just above the boom, but parallel with the boom.
Gerald, in Hawaii, mounted a roller furler behind the mast, parallel with the mast. He's gotten that to work out.
It seems that this might even be simpler... It would likely provide even less of a performance penalty, than Gerald's mod, and not add significant wieght aloft...
I'm not up to it, but I don't see why wtelliott's idea wouldn't work...
With the system you describe, you couldn't use a boom vang and I've not yet seen an X or M that was sheeted at the end of the boom.
But, what wtelliott is describing is (I think) taking a roller further system and mounting it just above the boom, but parallel with the boom.
Gerald, in Hawaii, mounted a roller furler behind the mast, parallel with the mast. He's gotten that to work out.
It seems that this might even be simpler... It would likely provide even less of a performance penalty, than Gerald's mod, and not add significant wieght aloft...
I'm not up to it, but I don't see why wtelliott's idea wouldn't work...
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Lease
- First Officer
- Posts: 290
- Joined: Thu Nov 17, 2005 3:07 pm
- Location: Canberra Oz; 1995 26X "MACMAC" Tohatsu 50
DLT - You are absolutely right about the vang (a detail I forgot), though it never caused us much of a problem. We used a snap shackle on the boom end to ditch it. It could be argued that reduced sail obviates the effect of the vang to an extent as the centre of effort moves forward, but wouldn't want to push the point with a performance hound.
As far as end-boom sheeting is concerned, I confess to being an ignoramus in regard to the M, but the X, my X anyway, is.
As far as end-boom sheeting is concerned, I confess to being an ignoramus in regard to the M, but the X, my X anyway, is.
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Frank C
I have not seen anyone express intentions to acquire the CDI mainsail furler ... beyond basic discussion in this thread. But without intent to specifically criticize CDI, I just don't see how a mainsail furler with flexible foil makes any design sense at all. In fact, the design is backwards. Even CDI's primary photo of the reefed mainsail shows the foil curving back from the mast (in zero winds?).
That's precisely the opposite luff behavior intended by the sailmaker.
Further, if your sail was designed with battens (a show of hands, please, if your mainsail has battens?), then you need to fly it bare. Further, all 26X mainsails have a luff-curve to match a 2 to 3-inch mast bend, so I cannot see how any of our factory mainsails will roll neatly. For starters then, you really should order a new mainsail to go with this design.
Even with a multi-boatbucks in-mast furler, its steel mandrel will suffer some reverse bending as wind fills the sail ... so it's surely inevitable with the flexible foil. Therefore, even with a luff pad in the mainsail, as wind speeds build, the sail will balloon as the plastic foil bends aftward. That's precisely the opposite of desired behavior. After installing the main furler, it seems there is no sail control to limit this effect.
Even the fancy boom furlers have this design fault. However, the boom mandrel is only 10 feet long (in Macgregor scale) compared with a luff mandrel of 25 feet ... again, the mast-furling design seems inately backwards, but vastly more so when the mandrel is plastic.
CDI's "marketeers" claim that modern mailsail fabrics demand only slight luff tension (50 pounds?) ... and only very slight adjustment for changing wind conditions! That's directly opposite of the anecdotal evidence I read in this forum. Guys here are using winches to gain a clean hoist on these little sails. How can one expect to do so with CDI's internal halyard? How can one improve halyard tension when the wind pipes up? I suppose this answer is, "... go on deck to fuss with the internal halyard!"
But isn't avoiding the deck a primary reason for roller-reefing the main?
As mentioned right at top of this thread (post #2), mast furling designs already have the inate disadvantage of permanently holding more weight aloft - much more than the basic flaking system, and more also than a furling boom. If the mast-furler jams, there's no quick way to reduce sail aloft. With our water-ballasted design, these are not the boats to tolerate added weight aloft.
Sorry, but beyond the obvious, initial cost of this system, it probably also demands a new mainsail. It seems to offer mostly disadvantages in the design, far beyond those that attach to headsail furlers. Seems from here that mainsail furling/reefing is best at the boom ...
whether flaking, rolling on-boom, or rolling in-boom.
That's precisely the opposite luff behavior intended by the sailmaker.
Further, if your sail was designed with battens (a show of hands, please, if your mainsail has battens?), then you need to fly it bare. Further, all 26X mainsails have a luff-curve to match a 2 to 3-inch mast bend, so I cannot see how any of our factory mainsails will roll neatly. For starters then, you really should order a new mainsail to go with this design.
Even with a multi-boatbucks in-mast furler, its steel mandrel will suffer some reverse bending as wind fills the sail ... so it's surely inevitable with the flexible foil. Therefore, even with a luff pad in the mainsail, as wind speeds build, the sail will balloon as the plastic foil bends aftward. That's precisely the opposite of desired behavior. After installing the main furler, it seems there is no sail control to limit this effect.
Even the fancy boom furlers have this design fault. However, the boom mandrel is only 10 feet long (in Macgregor scale) compared with a luff mandrel of 25 feet ... again, the mast-furling design seems inately backwards, but vastly more so when the mandrel is plastic.
CDI's "marketeers" claim that modern mailsail fabrics demand only slight luff tension (50 pounds?) ... and only very slight adjustment for changing wind conditions! That's directly opposite of the anecdotal evidence I read in this forum. Guys here are using winches to gain a clean hoist on these little sails. How can one expect to do so with CDI's internal halyard? How can one improve halyard tension when the wind pipes up? I suppose this answer is, "... go on deck to fuss with the internal halyard!"
But isn't avoiding the deck a primary reason for roller-reefing the main?
As mentioned right at top of this thread (post #2), mast furling designs already have the inate disadvantage of permanently holding more weight aloft - much more than the basic flaking system, and more also than a furling boom. If the mast-furler jams, there's no quick way to reduce sail aloft. With our water-ballasted design, these are not the boats to tolerate added weight aloft.
Sorry, but beyond the obvious, initial cost of this system, it probably also demands a new mainsail. It seems to offer mostly disadvantages in the design, far beyond those that attach to headsail furlers. Seems from here that mainsail furling/reefing is best at the boom ...
whether flaking, rolling on-boom, or rolling in-boom.
Last edited by Frank C on Sun Aug 20, 2006 12:43 pm, edited 1 time in total.
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Frank C
Hmmmm .... maybe one could "design to" the flex-luff problem?
Could a sailmaker build a reverse-luffed mainsail ???
(that would requre a fourth dimension! or at least Frank M's fourth mode of sailing?)
Could a sailmaker build a reverse-luffed mainsail ???
- - such that the stronger the wind blows,
- the more the luff flexes aft,
- and the flatter it pulls the sail's belly!!
(that would requre a fourth dimension! or at least Frank M's fourth mode of sailing?)
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Terry
- Admiral
- Posts: 1487
- Joined: Thu Feb 19, 2004 2:35 pm
- Sailboat: MacGregor 26M
- Location: Vancouver, B.C. Canada. '03 26M - New Yamaha 70
Ressurection
OK, I just had to resurrect this one because I found a boom roller that I'd like others to comment on. Check out this site and see what you think, then post your comments.
http://www.acmo.fr/nautisme/nouveaute/n ... isme_E.htm
http://www.acmo.fr/nautisme/nouveaute/n ... isme_E.htm