In-mast vs in-boom furling

[Wavehiker]

In-boom furling is a standard option from X-Yachts. No issues getting one for my boat.

[Dockhead]

Originally Posted by a64pilot

A boom furled sail can have a lot of roach, I don’t believe an in mast can though?

Correct. Big plus of boom furling. You can have just as much roach as a normal main can have.



I've heard that with vertical battens it's possible to have a bit of roach with in-mast, but I don't know that for a fact. I do know that my sailmaker, a renowned Solent guy with more Cowes Week wins than any other sailmaker, recommended a straight leech, not a roachy one, with carbon vertical battens, to go with the carbon laminate sail. I followed his advice. It works well and is pretty fast; I make 200 mile days quite often and have cracked 110 miles in 12 hours on occasion.

[Dockhead]

Originally Posted by a64pilot

Of course it would, but it’s pretty easy in the design phase to calculate that and build to compensate, so that even if a little heavier, it’s just as strong. You just don’t, or I haven’t heard of mast failures without the rig going first, surely it’s rare?
Now in mast of course means more weight up high, but again as most new boats come this way, surely they are ballasted to take this higher mast CG into account.

In other words surely those things have been accounted for in the design of the mast, and boat it’s going on.

Yes, if you've ever seen an in-mast furling mast, they are massively strong and, unfortunately, less flexible than a normal mast. The weight aloft of this heavy spar with rolled up mainsail inside is a definite minus, but to some extent compensated with more and/or lower ballast. My boat has 8 tonnes of lead in a bulb keel.

[CarlF]

Last three boats have been Doyle Stack Pack (on a Sabre) , Selden InMast (a Discovery), Schaefer InBoom (Shannon).

I've like the Schaefer in-boom the best. The sail was designed by Mack with a lot of roach, full length horizontal battens - even a slightly square top. It's a very powerful sail compared to my old in-mast sail which even had vertical battens. The Schaefer articulating mast track makes it easy to reef on a run. This is a huge improvement over the Leisurefurl boom. I use an electric winch and a small snubbing winch to keep tension on both lines. This makes everything wind neatly. This is no big deal. It's no different than keeping some tension on your genoa sheets when furling to get a neat wrap - or when unfurling the genoa keeping some tension on the furling line as it goes out so it doesn't make a mess in the furling drum. If you can't afford an electric winch for the halyard, in-boom isn't the system for you.

The Selden in-mast never jammed. It was stiff at first until a rigger figured out that the PO had put too much pre-bend in the mast. In-mast furling masts should have little to no pre-bend. It also took a while to learn the right amount of tension to keep on the outhall to have the smoothest operation. Like most boat systems, you need to learn its quirks. But as someone else said, you don't have to be all that careful. Sail jams were not in the top 10 of things I worried about when out for a sail.

The big negative with in-mast was sail shape. It just wasn't a very powerful sail. I believe the reason that the European builders like Oyster and Discovery use in-mast is just market expectation. II read that 80% of new European delivered monohulls over 40ft have in-mast furling. No builder is going to fight that statistic and risk a sale by trying to talk someone into in-boom when he makes just as much money on in-mast.

I would not go back slab reefing or a stackpack unless the boat was less than 35ft - at which size the mainsail is pretty small and easy to handle. The reason is 1) Comfort: It is so easy to reef that you never "wait too long". It's so easy to reef that I'll roll in a foot just to balance the helm. 2) Performance - on most boats performance is better if you reef the main before the headsail. But with a hard to reef main, people roll up the genoa furler destroying sail shape and sheeting angle. 3) Safety: With either in-mast or in-boom, no one ever as to leave the cockpit to tend sails. I think this is critical for a husband/wife team - especially if they are over 50. While the Doyle and Jiffy reefing is supposed to avoid that, I found that 1/4 of the time something would hang up requiring leaving the cockpit. It's never been necessary with in-boom or in-mast.

The only real issue with the in-boom is leach control. It's really easiest to have a permanently set vang to keep the boom-to-mast angle just right. This means you need a sailmaker with a lot of experience with these sails. They need a double layer of cloth on the leach to keep it from stretching. And you adjust the leach tension by furling the sail a few inches - but only if the sailmaker cut it that way. I think this is another reason the boom furlers are less popular in Europe because the local sailmakers don't have much experience with these sails.

But as to the question of in-mast or in-boom, I'd be happy with either. There are many more important choices when buying a boat.

[flyingfin]

Neither! Unless you only go out on calm days, only sail downwind or must need to push a button to do everything for you. Real sailors learn how to raise and lower mainsails, and they can actually sail into the wind. Every boat I have been on with main furling sails like a log. I learned as a child to run the mainsail up or down while Dad ran the helm. Less things to go wrong.

[Medved]

Thank you for this info. Exactly what I was looking for to understand trade offs

[daletournier]

Originally Posted by flyingfin

Neither! Unless you only go out on calm days, only sail downwind and want to push a button to do everything for you. Real sailors learn how to raise and lower mainsails, and they can actually sail into the wind. Every boat I have been on with main furling sails like a log. I learned as a child to run the mainsail up or down while Dad ran the helm. Less things to go wrong.

We did a 1950nm passage recently averaged 178nm/day, not bad for a dog.

[Medved]

Originally Posted by flyingfin

Neither! Unless you only go out on calm days, only sail downwind or must need to push a button to do everything for you. Real sailors learn how to raise and lower mainsails, and they can actually sail into the wind. Every boat I have been on with main furling sails like a log. I learned as a child to run the mainsail up or down while Dad ran the helm. Less things to go wrong.

I understand your point, but unless you have this consistent approach, meaning you do not have a motor on your boat or any electronics to keep things simple, I think this is not an argument I can get behind

[Training Wheels]

Originally Posted by a64pilot

I don’t know, boom furling isn’t new by any means, which boat manufacturer sells boats equipped with them?

I don’t understand the comments on getting the boom angle right is a pain.
It’s a set once and forget it thing, and it’s dead easy to do. You know the boom angle is correct when it aligns perfectly with the battens, if the sail is walking forward when being furled the tail end of the boom needs to come up a little, if it walks aft, then lower it a little.
If I, a non Sailor can figure it out, it must not be hard.

My system has a nitrogen gas pressurized Vang. In order to use a boom brake and I’d assume a preventer if it pulls down on the boom, you need a topping lift so that this downward pressure doesn’t collapse the Vang, or I guess you could run a solid Vang?

Now you give up being able to control sail shape with the Vang, and this is a disadvantage.


One thing that is curious, and that’s I’ve not seen a Cat with either system, why? It’s not due to cost I’m certain of that.

Maybe because most people don’t want to climb up on the boom to remove the batten for the square head main?

[Cliffhanger]

I have a boat (36ft Catamaran) with in-boom furling. I am soon going to change it for slab reefing.



All systems have their pros and cons but the biggest con with in-boom furling is that the sail has to be carefully rolled onto the boom. This can only happen if the boom is exactly horizontal. This is easy enough when motoring upwind but almost impossible when there is wind in the sail. So, when the wind picks up and it is time to reef the main, I have to furl the genoa, start the motors, heading upwind, furl the main, bearing away, unfurling the genoa and stopping the motors. Not a fun thing to do when the wind gets up.



Slab reefing is simple, reliable and reefing while on a reach or closehauled is easy.

[a64pilot]

Originally Posted by Training Wheels

Maybe because most people don’t want to climb up on the boom to remove the batten for the square head main?

Why would you have to remove that batten?
Even if you did it shouldn’t be an issue, cause if your fully putting the sail away your going to have to climb up there to remove the halyard, or the thing will be banging away in the wind.

No I assume whether correctly or wrongly that in boom just can’t quite equal a regular main sail performance wise, and Cats I believe derive most of their sailing performance from the main sail, where as I believe many mono’s are mostly head sail driven, so Cats go with the highest performance main sail?

[Training Wheels]

Because on square top sails the top barren runs diagonally. How are you going to roll that up?

[jmschmidt]

It appears that one of your motives in taking the ASA courses (nothing wrong with that) migt be to do some chartering in areas where it, or the RYM designations, are required. If so then the in-mast or in-boom should be fine. Or if you plan to just cruise your own boat close off-shore and/or in protected waters with believable weather windows. On the other hand if you want to go way off-shore on longer trips or do an ocean crossing I'd avoid in-mast and in boom equipment.

If I were doing this (and I have) I'd even think about using hanked on headsails. I can tell you about a 72K squall that came up out of nowhere at night in the middle of the Gulf of Mexico. It blew the strap on the boom vange and the main slammed into the lee spreaders and shrouds. It took me a half hour to get the main down, inch by inch, while waves broke completely over me and I disappeared in the foam. The cockpit crew said it looked like I was on an episode of the "Deadliest Catch."

[Derick Warne]

Originally Posted by Medved

Hi all, I am a power boater who is converting to sailing. Passed ASA 101 few weeks ago and scheduled 103/104 for mid Sep. I am still in my research phase as to which boat to go after. I will be sailing single handed or short handed, and really liked in-mast furling on a Jeanneau 440 I got a chance to sail. That said, I am trying to understand pros and cons between in-mast and in-boom. I saw in and around Annapolis a number of ocean going sailboats with in-boom furling, but cannot find much info on those. Any insight from folks who have sailed with these are greatly appreciated.

For a professional, unbiased opinion you might contact Terry Clarence at Rolly Tasker Sails Annapolis.

[MicHughV]

this is a no brainer......

If you have in-boom furling, and you have a screw-up somewhere, you can always pull the mainsail down by hand..
screw ups usually happen at night in 50 knots of wind....not the place or time to be worrying about reducing sail....
in-mast furling is a disaster waiting to happen in my opinion.....a slight miscalculation on the rotation and tension of the in-mast furler and the main will bind up and not go roll up anymore....hardly what you want when the wind is howling...sometimes your only option is to completely unfurl the sail...practice doing this at night in 50 knots of wind....oh yeah...you will probably be heeled over 45 degrees....add that to the complexity...
a few more things to consider, in-mast mainsails are usually formed without a roach, a so called-hollow roach, though I have seen vertical battens on some in-mast furlers to provide some additional sail area. If a batten shakes loose while furling or unfurling....good luck to you.

keeping a mainsail furled inside a mast also adds weight to the mast....you'd be surprised at how much that can add to over turning moment...
you may need to furl the main during a rainstorm, which means it will be wet, adding to the weight and complexity of furling a wet sail..
I have experienced both....I like neither.....but mostly I dislike the in-mast concept.
I think it's a fad to sell new boats imo and a nod to all lines being led to the cockpit.....blah, convenience should not outweigh common sense....pure ********.....go to the mast and pull the mainsail down by hand....you can see and control what is happening.

lordy, lordy, lordy.....the modern day sailor is becoming a slave to " modern" convenience....electronics out the wazoo....in-mast furlers....all lines led to cockpit...and a myriad more things.....dockside queens....these boat hardly ever leave the dock in anything over 5 knots ...

ok, my rant is over.....good luck to you all....see you on the water...maybe ??