Boom Furling Questions

Tedd

.
Jul 25, 2013
465
Between Boats near Vancouver, BC
I'm posting this in the cruising forum because I think the answers to my questions may be quite different depending on the context (cruising versus racing, for example), and I'm only interested in the answers as they pertain to cruising.

I was watching a video on Schaefer boom furlers and wondered about a couple of things. To what extent does the Schaefer system (or a similar system) affect mast bend? Presumably, it makes the mast stiffer, thereby reducing mast bend for given stay and sail loads. Or is the sail track designed so as not to influence the bending stiffness of the mast? If the system does make the mast stiffer, does one just accept less bend, or can the greater stiffness be compensated for with stay tuning? Also, the Schaefer system moves the sail aft, relative to the mast, thereby (other things being equal) moving the center of effort aft. Is this usually compensated for in the shape of the sail used with the boom furler (i.e., roach) or is it compensated for by mast rake (or both)?
 
Jan 11, 2014
7,827
Sabre 362 113 Fair Haven, NY
Generally mainsail furling systems are designed and built for ease and convenience, not sail control and speed. The sails tend to be a bit smaller and battens are an issue as they don't roll up well.

A furling mainsail will not have the same shape or be as shapeable as a well designed loose footed mainsail.
 
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Tedd

.
Jul 25, 2013
465
Between Boats near Vancouver, BC
Thanks, @dlochner . I expected that would be the case, but I'm interested in what mitigating features or strategies might be employed.
 
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Feb 10, 2004
3,508
Hunter 40.5 Warwick, RI
I have the Schaefer Gamma (larger) boom. 6-7 years experience with it. My recollection is that there is a specified limit for pre-bend. I think it may be 3-5", but I am not sure. My rigger took care of that. If the additional stiffness is thought to be due to the track, I doubt any additional stiffness is present.
Having the main sail moved aft by 4-5" is insignificant IMHO.
If the sail is a few square feet smaller (it may or may not be) as cruiser I don't think you would notice.
As for the battens rolling up, mine roll up flawlessly. You can furl and unfurl 45 degrees off the wind. One of the important advantages of boom furling is that you can maintain sail shape with full length battens.
I can't speak to loose-footed mains because I have no experience with them.
As an aside, compared to other manufacturers of furling booms, my opinion is that the Schaefer design is superior.
 
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Tedd

.
Jul 25, 2013
465
Between Boats near Vancouver, BC
Thanks, @Rich Stidger , that's very helpful. Any thoughts on boom furlers for a smaller boat? I'm shopping for a Hunter 260 and thinking a roller main would be nice, but I can also think of some disadvantages. The boom might be a lot heavier to handle when taking the rigging down, for example. And the sail track might complicate things, too. (I trailer a lot.) On the other hand, other than weight it might actually be easier than stowing a regular sail and boom.
 
Feb 10, 2004
3,508
Hunter 40.5 Warwick, RI
@Tedd - Schaefer makes a smaller version but I dont know what length boom it will replace. All of the furling booms are heavy and a boom brake is highly recommended.
Knowing the setup I would not think boom furling would work well for a boat that is trailered. At least not for the Schaefer or Leisure Furl.
 
Jan 11, 2014
7,827
Sabre 362 113 Fair Haven, NY
Thanks, @Rich Stidger , that's very helpful. Any thoughts on boom furlers for a smaller boat? I'm shopping for a Hunter 260 and thinking a roller main would be nice, but I can also think of some disadvantages. The boom might be a lot heavier to handle when taking the rigging down, for example. And the sail track might complicate things, too. (I trailer a lot.) On the other hand, other than weight it might actually be easier than stowing a regular sail and boom.
The mainsail on a 26 foot boat is pretty small and light. It's hard to see the advantage of a an expensive fuller for the boom. A better alternative is a Stack Pack or Mack Pack whatever the local sailmaker calls them.

 
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Feb 11, 2017
121
former Tartan 30 New London, CT area
As a furling system, this may work fine. Eliminates doing a harbor furl, putting on sail ties, and installing a cover (which I did for many years on different boats).
What's missing is any discussion of reefing. How would I put in a first or second reef? I've had boats that had a roller boom - both got converted to slab reefing. First one it took me a while to realize the roller boom wasn't doing the job. Later boats got converted right away.
I suspect this system is fine up until you need the first reef. Looks like then you're supposed to furl the entire main and go under power.
 
Feb 10, 2004
3,508
Hunter 40.5 Warwick, RI
As a furling system, this may work fine. Eliminates doing a harbor furl, putting on sail ties, and installing a cover (which I did for many years on different boats).
What's missing is any discussion of reefing. How would I put in a first or second reef? I've had boats that had a roller boom - both got converted to slab reefing. First one it took me a while to realize the roller boom wasn't doing the job. Later boats got converted right away.
I suspect this system is fine up until you need the first reef. Looks like then you're supposed to furl the entire main and go under power.
My Schaefer boom furler will reef at many points. The instructions say to roll up the sail until one of the full battens is just on the mandrel. Then re-tension the main halyard. Another 1/4 turn of the mandrel will tighten the sail very nicely. The most useful reef points are at my lower two battens.
I think the reason that the old roller booms never worked that well is because the main sail was not cut for that application.
 
Feb 11, 2017
121
former Tartan 30 New London, CT area
I think you're right. The old roller furl booms didn't use mains with full battens. With a full batten at the reef point, the batten provides tension in the foot of the sail.