In mast furling or slab

[Sailor Doug]

My Seldan RFA has jammed less than my RFJ in the last 12 years. There are some distinct rules when furling that must be followed, not using them and you become one of those nay sayers. Slab reefing works well for thirty foot but beyond that a third reef leaves a lot of line dangling when the sail comes down. Off shore I would want more than three feels, but I like fractional rig boats.


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[David B]

Originally Posted by ironmandel

Hi I'm looking to buy a live aboard and ultimately trans Atlantic onwards to circumnavigate . I have been told in mast furling is a no no go for slab . Reasons given are that in mast tend to jam and if in a pickle or if the weather should pick up then I could find myself not being able to drop the main
Any thoughts or experiences please


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There is some good advice here from other contributors, and as we would all expect, it is from various perspectives and experiences.
A couple of things I note is that from what I can gather, the equipment-based bad experiences are generally related to older equipment (a lot can change over a few decades). Also, from earlier threads I gather that some furling systems are not as good as others, so in your evaluation, you need to check brands being referred to, as well as their age.

I agree there are advantages and disadvantages of any system. The world remains far from perfect, and we just need to go with the best we can find, that suits best, our own circumstances.

As to our own experience, when we committed to our new yacht back in 2011, we were advised it had in-mast furling.
Never in a fit would I have had in-mast furling by choice - I was fully aware of all the issues one hears about such as jamming, the weight aloft causing more rolling (especially at anchor), and the loss of sail area with the roach gone. However being the last model available, we had no choice - take it or leave it.

I did a lot of web trawling back then, and I never managed to find a single case of an in-mast system jamming when furling - only a few jamming when un-furling, and in all cases it was due to a loose furl causing bunching of the sail in the slot.
The dealer told us we could order a normal mast at our cost, but advised "try it first - it will become your friend".

So we decided to go for it. The system is Selden, on a 15m / 50' mono.

So now it was time for us to experience first hand, all those issues I was aware of:

1. The extra rolling at anchor is not an issue - when there is swell around, there are many that roll a lot more than us.

2. I have only noticed lack of sail area once so far when a smaller yacht was overtaking us - then the wind came in, and we rocketed ahead of them. So, if we are fussed, we need to get a Code zero or similar, but frankly, I don't think we are bothered at the moment anyway. Reaching at 9.8 in 14 true is good enough for us.

3. The system is dead easy to use - single-handed. A little off the wind to maintain some tension, one hand on the winch, one on the boom outhaul, (round a spare winch for some friction) with the lazy end of the furling line also running through that hand, and the sail is furled before you know it (especially if the winch you use is electric ). Out is similar, and at least as easy.

4. We very quickly came to realise that for a couple in their sixties, the main on a 50' yacht is quite a handful, and there would be many occasions when we would just sail under headsail to avoid the hassle of unzipping/zipping a boom-bag, hoisting/reefing etc, then flaking back properly into the bag. Bad enough at the end of season getting the thing flaked on the boom, then off and folded. Sailing is supposed to be more pleasure than work.

5. We see an awful lot of yachts 40'-55' with in-mast these days.

6. We see a few with in-boom furling, but it seems more reserved for larger yachts, and seems to be standard for super-yachts. That's a big heavy boom to swing around, and from what we hear, they are very fussy about having the angle just right, or you are in trouble with the furl.

In our experience, the dealer was correct - it 'became our friend' very quickly, and frankly, we would not consider a yacht without now, but for a fully crewed yacht, with performance in mind, then that's a totally different story.

As to issues down the track, I expect the time will come when we need to have the sail either re-cut, or replaced to keep it flat enough to furl without trouble, but in the meantime, the ability to single-handedly look after reefing is much appreciated, as is the ability to infinitely adjust the amount of sail out to suit conditions.

Rounding a notorious cape (Cap Bon) off the coast of North Africa, we had decent seas (kept coming into the cockpit looking for us) and wind gusting well into Force 9. We were motor-sailing close-hauled with main wound in to about the size of a storm trysail, and the headsail similarly furled, making good progress.

Apart from the expected apprehension of a couple who did not have a lot of miles under their belts, at no time did we have concerns for our boat or its rig. I really would not have wanted to be dealing with slab reefing under those conditions, and having all of the slabs sitting on the boom causing windage. I do like jiffy reefing - we have it on a much smaller sail boat, with two reefing lines led back to the cockpit. However the in-mast furling on our larger boat is for us, they way to go.

Your choice of course, but there is another perspective for you to hopefully help with your deliberations. Whatever you go for, I hope you have some great experiences, and many happy years with your new boat.

David

[ironmandel]

Many thanks lots to think about lots to try and asses so looking forward to it all 😎


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[mattangels]

I have in-mast Hunter 46. Had some jams and worried it might happen at a bad time. Learned to keep tension on the out-haul when furling. Never jammed again. I LOVE HER!

[David B]

Originally Posted by mattangels

I have in-mast Hunter 46. Had some jams and worried it might happen at a bad time. Learned to keep tension on the out-haul when furling. Never jammed again. I LOVE HER!

Yes, that is one of the key things - keep that furl tight, and you should be fine. Regular checks of the furling mechanism is another thing - you don't want bearings falling apart due to loose locking screws etc at the wrong time (which of course it always will be ).

One season, we were a day out and I noticed the tack loop had nearly come off the horn at the bottom of the furling system. Got it back on again with a bit of twisting and stress (bent the marlin spike on my knife doing it), and we were fine.

The lesson I learned there, was when bending the sails back on at the beginning of the season, make really sure that the luff is properly tensioned. We thought it was, but a bit of wind in the morning we were doing it, caused enough pressure on the sail, and therefore friction in the luff-groove to prevent the luff bolt-rope sliding easily enough for a proper tension. Then when sailing and tacking, the luff eased through the tack, and the loop nearly came off.

These days, I always let the sail flutter a bit while tensioning, to ensure that the luff bolt-rope slides all the way freely, and I am tensioning the luff, not pulling against friction in that groove.

I like sailing - it keeps you on your toes.

[Duplexity]

No big issue with furling but back to the thread and question of choice.
I will start with a clear trend by new models launched during last decade.. If you look at the sail plan, 10-15 years ago main area was only about 45%, but today in new designs it’s much more = about 55% (due to upper shrouds attached out at toe rail which means head sail is limit in area). This means today it’s more important to have an efficient main sail.

A full batten main (slab) is much more efficient than a furled so if you want speed the choice is easy. This is true even if furled has standing battens. And reasons are; larger sail in the upper part (most important there), more efficient camber/shape and not at least much easier to trim (camber, twist, luff/Cunningham). There is another opinionen about reefing and you can reef continuously with furling main; true but you will get an further more inefficient sail when furled “half” = camber not where it should be (compare when furling/reefing head sail with or without compensation pad along luff). In my opinionen trend favors slab with easy handling in a combo of lazy bag, single reef line and electric winch for halyard (still you need to close zipper and disconnect halyard but manageable). Two reefs are enough and with unchanged camber when reefed.

But said that, we might talk about a half knot speed or less for a 40 footer and if you at the same time heading for a cruiser as Bavaria or Jeanneau the choice might not be wrong of a furling main. If you consider a “performance cruiser” or a Hanse your choice should be a slab…

Guess my choice.. ☺
Elan 450 Charter, Rental, Greece, Duplexity

This video when cruising without engine in light wind.

http://www.youtube.com/watch?v=sNjcpA6q-2s

[jackdale]

I have sailed both. I prefer a slab system:

- better sail shape.
- more sail area
- no jamming (I have had both furling and unfurling)
- easier to reef from close reach to broad reach
- flatter, depowered sail when reefed

Add an adjustable back stay or baby stay for depowering a full main.

For slab reefing I prefer a luff rams horn (or similar system) and a leech reefing line to single reefing. Way less friction and less chance of twisting lines inside the boom.

[Sailor Doug]

Double reefing lines are easer and safer than horns. I have graduated to RF fractional main and am loving it.


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[Dockhead]

Originally Posted by Duplexity

No big issue with furling but back to the thread and question of choice.
I will start with a clear trend by new models launched during last decade.. If you look at the sail plan, 10-15 years ago main area was only about 45%, but today in new designs it’s much more = about 55% (due to upper shrouds attached out at toe rail which means head sail is limit in area). This means today it’s more important to have an efficient main sail.

A full batten main (slab) is much more efficient than a furled so if you want speed the choice is easy. This is true even if furled has standing battens. And reasons are; larger sail in the upper part (most important there), more efficient camber/shape and not at least much easier to trim (camber, twist, luff/Cunningham). There is another opinionen about reefing and you can reef continuously with furling main; true but you will get an further more inefficient sail when furled “half” = camber not where it should be (compare when furling/reefing head sail with or without compensation pad along luff). In my opinionen trend favors slab with easy handling in a combo of lazy bag, single reef line and electric winch for halyard (still you need to close zipper and disconnect halyard but manageable). Two reefs are enough and with unchanged camber when reefed.

But said that, we might talk about a half knot speed or less for a 40 footer and if you at the same time heading for a cruiser as Bavaria or Jeanneau the choice might not be wrong of a furling main. If you consider a “performance cruiser” or a Hanse your choice should be a slab…

I think most of what's in this post is generally true, but I will quibble with the bolded part about reefing. This coming from a person who sails in windy latitudes, mostly with a reef in the main.

For some reason, furling mainsails on the contrary do NOT lose their shape when furled, the way headsails do. I can't explain why that is exactly, but it's true -- they become flatter as they go in, which is just what you want -- depowering through shape as well as area. The downside is that the first third of the mainsail is doing little work in any case due to wash from the headsail, so if you reef by 1/3 you've lost 1/2 of that part of the sail which is actually doing anything. However, since acquiring a non-overlapping blade jib last year this effect is much less, when I'm using that headsail.

The shape of roller furling headsails goes to pot when furled, with or without luff pads. To such an extent that I have even toyed with the idea of trying hanked-on headsails. My guess is that the roll of furled up sail breaks up the air flow and depowers the forward part of the sail, on top of the loss of shape.

Why the loss of shape works differently, I also can't say, but perhaps it's related to the fact that a furling headsail is on a stay, and the stay is not vertical, so the geometry of the forces involved is different, than the case with furling mains, which are on foils which are vertical.


In any case, I try to avoid as much as possible ever reefing my overlapping headsail. Changing sails is a lot of work and I can't do it single handed, but if possible I change down to the blade, whenever I expect I might need to reef.

Then I reef the main first, and reef the blade only as a last resort (i.e. practically never). Sometimes I even put the main away altogether and sail on the blade alone (I was amazed, but this causes no helm balance problems). Around this point (30-32 knots) I can also put away the jib and change to the staysail anyway and roll out the main if necessary.


So in summary, although I sure miss the roach of a full batten main, in-mast furling is quite ok for our windy latitudes up here, and probably performs better than full batten. In milder latitudes, however, where you don't reef as much as we do up here, I would definitely want a full batten main. Maybe a flattop main actually. The roach is key to power out of the mainsail in light conditions.

[chuckr]

Originally Posted by Windsurfer

I recently changed from a furling main on a Bene 393 to a traditional main on a Jeanneau. I am sold on the classic main because I was recently caught by surprise by a 27 kt. puff (?) squall (?) at night sailing out the Golden Gate, single handed as usual. I was able to reef the main and gain control over the boat. I would have been hosed with a furling main. So, the ability to de-power quickly trumps, in my mind, the convenience of furling. Plus, I like having a proper sail with a roach.

WOW -- you got a 27k powerful blow and how would know you could not handle it with inmast. We sail a Jeanneau DS40 with in mast and have seen a lot more than that and we have never had a problem. If you knew how to handle it it is not a problem -
8 years underway - probably over 30k miles and never an issue in furling in the main. NONE


by the way just read my response to the Admiral and she laughed at a 27k gust and said good grief we got that sometimes just walking down the dock let alone we get out in the islands.

[chuckr]

Originally Posted by sailon46

Place yourself in your future boat sailing north on the leeward side of Grenada full sails nice breeze and a fast moving squall comes down the mountain and hits you broadsides at 50+knts. Slab and drop the main in a second or two saves the boat and you, while cockomimi in mast or in boom furling either blows out or badly tears up the main or slams the boat in the water broadside. I know I was there. For what its worth.
Ernie on the Mary Jane

Been there have you? We sail a Jeanneau DS40 and sailed those islands a couple of times up and down and yea we got a lot of gust especially off the end of the islands with a volcano on the end and the winds come roaring down - or the land breeze off the south coast of the DR north of Santo Domingo or how about rounding a Greek Island to be greeted by a huge meltimi or a sudden thunder storm in the San Blas - we have had it all and no issues - we know how to handle both the boat and quickly reef the main for those winds

And when we sailed across the Atlantic we had 30-35k winds for 3 days and we reefed down both the main and the jib to just about handkerchief size - something you can not do with a conventional sail - , balanced the boat and had a smooth not pounding sail that was good for both the boat and the crew -

but then again we are not great sailors - we have no idea what we are doing from a technical standpoint we just sail and sail a lot of miles each year and visit a lot of ports, sail in a huge variety of conditions and actually do it instead of just thinking about it -

[Dockhead]

Originally Posted by chuckr

Been there have you? We sail a Jeanneau DS40 and sailed those islands a couple of times up and down and yea we got a lot of gust especially off the end of the islands with a volcano on the end and the winds come roaring down - or the land breeze off the south coast of the DR north of Santo Domingo or how about rounding a Greek Island to be greeted by a huge meltimi or a sudden thunder storm in the San Blas - we have had it all and no issues - we know how to handle both the boat and quickly reef the main for those winds

And when we sailed across the Atlantic we had 30-35k winds for 3 days and we reefed down both the main and the jib to just about handkerchief size - something you can not do with a conventional sail - , balanced the boat and had a smooth not pounding sail that was good for both the boat and the crew -

but then again we are not great sailors - we have no idea what we are doing from a technical standpoint we just sail and sail a lot of miles each year and visit a lot of ports, sail in a huge variety of conditions and actually do it instead of just thinking about it -

Indeed.

I didn't understand the comment about gusts.

With slab reefing, you could blow the halyard very quickly, if the halyard is led to the cockpit. Can't do that with in-mast furling. But this is a crude maneuver which will flog the sail. Is it any better than blowing the sheet? I don't really think so.

Short of that kind of thing, in-mast furling is much faster to respond to a gust, and you don't have to leave the cockpit.

In a big gust where instant relief is needed, I don't do any of this - I ease the sheet (not blow it) and head off. If there's crew at the mainsheet winch, this takes about 2 seconds. Then reef.

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[jackdale]

Originally Posted by Dockhead

For some reason, furling mainsails on the contrary do NOT lose their shape when furled, the way headsails do. I can't explain why that is exactly, but it's true -- they become flatter as they go in, which is just what you want -- depowering through shape as well as area. The downside is that the first third of the mainsail is doing little work in any case due to wash from the headsail, so if you reef by 1/3 you've lost 1/2 of that part of the sail which is actually doing anything. However, since acquiring a non-overlapping blade jib last year this effect is much less, when I'm using that headsail.

The shape of roller furling headsails goes to pot when furled, with or without luff pads. To such an extent that I have even toyed with the idea of trying hanked-on headsails. My guess is that the roll of furled up sail breaks up the air flow and depowers the forward part of the sail, on top of the loss of shape.

Why the loss of shape works differently, I also can't say, but perhaps it's related to the fact that a furling headsail is on a stay, and the stay is not vertical, so the geometry of the forces involved is different, than the case with furling mains, which are on foils which are vertical.

Have you considered the position of the tack of each sail? The tack on the main stays on the boom and foot tension is easily controlled, leech tension is still controlled by the mainsheet / vang. Without moving a jib car the foot tension on a furled jib is too tight and the leech is too loose . When furling a foresail you need to move to the jib car forward to ease the foot and harden the leech.

[Dockhead]

Originally Posted by jackdale

Have you considered the position of the tack of each sail? The tack on the main stays on the boom and foot tension is easily controlled, leech tension is still controlled by the mainsheet / vang. Without moving a jib car the foot tension on a furled jib is too tight and the leech is too loose . When furling a foresail you need to move to the jib car forward to ease the foot and harden the leech.

I'm somewhat familiar with the use of jib cars and balancing foot-leech tension

I have the heavy duty Selden towable cars and use them intensely.

I also have permanently installed barber haulers which allow me to keep tweaking sheeting angle if I run out of car track travel. With the same system I can tweak the sheets inboard and outboard if desired.

No amount of trimming makes a partially furled headsail work right.

It's also very hard on the sail, according to my sailmaker.

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[jackdale]

Originally Posted by Dockhead

I'm somewhat familiar with the use of jib cars and balancing foot-leech tension

I have the heavy duty Selden towable cars and use them intensely.

I also have permanently installed barber haulers which allow me to keep tweaking sheeting angle if I run out of car track travel. With the same system I can tweak the sheets inboard and outboard if desired.

No amount of trimming makes a partially furled headsail work right.

It's also very hard on the sail, according to my sailmaker.

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I started in the hank-on days and recognize that furling sails of any sort are a compromise in the name of convenience, sometimes a bad one.