In mast furling vs slab reefing

[boatmike]

Re: In boom reefing as opposed to the others

I think if you read my other post I did say that vertical battens restore the roach of the sail and therefore there is little loss of sail area. My own sail has vertical battens and is ALMOST as big an area as the sail would be if it were a normal sail.
It still has less roach than a sail with horizontal battens though, especially full length vertical battens that allow extremely high roach. You are also correct about loose footing but to be fair this can be achieved equally well with any sail. As this is supposed to be a debate between slab reefing and in-mast reefing I would suggest that the slab system still allows a bigger sail to be used and can also be flown loose footed so you cant really claim in-mast is better in that respect can you?
There is no such thing as a better mousetrap.......
A mouse can only die once........


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[Bejasus]

Re: In boom reefing as opposed to the others

not trying to make a point Mike. It's just that I had been looking at a boat recently which had in boom furling, and had a look at these sites to try and find out more, which is why I asked the question in the first place.

George

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[boatmike]

Re: In boom reefing as opposed to the others

Sure, sorry if I sounded abrupt.
The systems you draw attention to have indeed been used as FURLING systems on large yachts. They do solve a problem of stowing a large sail especially on a superyacht where the system is often motorised or hydraulic. Profurl in particular have applied their system to square riggers mounted on the yardarm and yachts of modern fore and aft design mounted on the boom. Mainly you will see them on yachts of 20metres OAL upwards as FURLING systems. You certainly would not contemplate furling the mainsail on Mirabella (that I was involved with at Vosper Thornycroft before I retired last year) without mechanical assistance. This is not the same however as a REEFING system. The manufacturers purport to achieve the same thing but they don't. REEFING assumes you can have a semi-furled sail that will be useful in increasing wind velocities. FURLING just gets the rags stowed away when not in use.
In-Boom furling systems are crap at reefing a sail regardless of manufacturers claims.
What we are talking about on this site is REEFING systems on vessels of under 15 metres. In this context keep it simple and go for slab reefing which can be operated "handraulically" or if you want the advantages (accepting the disadvantages) of a low risk reasonable performance system operated from the cockpit there is none better than a vertically battened mainsail and in mast reefing system.
Hope this clears up the misunderstanding and answers your question!

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[MainlySteam]

Re: In boom reefing as opposed to the others

I am on the fence and do not much care either way (mast or boom) because I would have (and do have) slab reefing myself.

However, everything about your post indicates that either you have in mast furling yourself and will see no other (in which case you do a disservice to those who have asked for advice), or you live in an uncivilised part of the world - in boom furling is commonplace and if you do not believe me I suggest that you look at what is being used on superyachts featured in the superyacht section of any Yachting World magazine. In fact I have to say that I personally know of or have been involved with more boats with in boom than in mast (including even a 28 footer).

The comments made by some comparing in boom with the boom roller furling of many decades ago is foolish and shallowly dismissive. Also, the faults and their solutions, suggested due to the fullness of sail, exist for both in mast and in boom.

Again, I emphasise that I would have neither, they both have problems which dismiss them as alternatives on non super sized sailboats as far as I am concerned, so my comments on the two methods are unbiased.

John

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[Ric]

Lemain, one feature of in-mast reefing that has been described by detractors as a disadvantage is the fact that there is more weight aloft because of the weight of skightly increased weight of the mast. This is true - though I am not sure it is terribly significant in terms of the overall position of the centre of gravity of the boat, especially on a cruiser. But in some ways this is an advantage - the sail is already "up". On a boat like a 43DS, there is a fair bit of winching required to hoist the mainsail. If you have in-mast, you have hardly any. I really like my system and think for leisurelycruising around the Med, I think it is great. My next boat won't have it though, because I intend to sail back to NZ and for reasons already given here I would rather have slab-reefing and a more robust boat for such a trip.

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[Bejasus]

Re: In boom reefing as opposed to the others

Thanks for that. My enquiry came about due to the fact that I am not a sail boater, but wish to go liveaboard in the Med in a few years and am currently looking at motorsailers. As it's just the 2 of us, I was looking at making things as simple as possible, mainly as I have stated to my wife, that she at least has to be able to handle the boat on her own in an emergency. You never know. However, as it is a ketch I am looking at, then I guess dropping the main and running on a partially furled jib and mizzen, would probably answer most of this.

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[MainlySteam]

<<<more weight aloft because of the weight of slightly increased weight of the mast.>>>

Not only the increased weight of the mast but also that the fact that the reefed sail's centre of mass also remains as it was (1/3 the way up the mast, so if your main weighs 20kg then you always have 20kg acting against your stability 1/3 of the way up the mast) when reefed or completely furled whereas with slab or in boom the centre of mass of the sail is taken down to boom level.

In my view this is mainly a concern in seas of shape or size for which stability is important. On the one hand the weight higher up increases the moment of inertia around the boats longitudinal axis which resists waves accelerating the boat into a roll, which is a benefit, but on the other hand stability is reduced once the boat is accelerated into the roll which is a disadvantage.

In my view, for most small boats which have furling type mainsail reefing systems (light displacement, often low ballast ratio) the loss of stability far outweighs the increased resistance to acceleration in a roll. We have a heavy displacement cruising boat (about the same displacement/volume as a Hallberg Rassy, for example), and I would not wish to have unwanted 20 kg 1/3 way up my mast in sea conditions where the wind conditions meant that the mainsail was completely down/furled.

The increased weight aloft also has an effect on the moment of inertia about the transverse axis of the boat which slows pitching accelerations also (and also imposes a small penalty on speed, but not of consequence in a cruising vessel but fatal to a race boat). Again, most small yachts in which such furling systems are installed are light and tend to have flat fore sections and tend to slam. Having extra weight aloft may reduce the pitching and consequent slamming from pitching but is not something I have investigated - however, any such advantage, in my opinion, would be far outweighed by the loss of stability.

John

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[Anonymous]

Ric, This thread has been a terrific help to me. So much personal experience and open-mindedness is unusual in any thread. When it comes to selecting a 43DS (if that's what we finally get) I shall judge the vessel on other factors. I might even find a slab-reefed example at a bit of a discount because in-mast is the vogue. I would want all the lines led back to the cockpit, though. I really don't want to have to go on deck for such a routine operation. If something jams then that's different, but hopefully it will be rare or perhaps never happen.

Just one point - a 43DS with a nice spec at a fair price has just come on the market but the spec says that the third reef line is not led back to the cockpit. Why should that be, any ideas? From the rest of the spec I suspect that the owner was a very experienced sailor so maybe there is a good reason?

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[MainlySteam]

Often the third reef line is not rigged because of its length and that is also frequently so even when none of the the lines are led back to the cockpit.

There is often a permanent mousing line in the leech of sail from the second reef point to the third to pull the second leech end reef line up to use when one requires the third reef (otherwise one feeds it through by hand) - one assumes that one will have to go on deck to do so but in normal events that would not be a very frequent occurance if the reefs are all of conventional depth.

I am only familiar with the USA specs for the Jeanneaus but if the European ones are the same then the third reef would seem to be have been an extra, requested or later fitted by the owner, on the 43DS.

John

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[Anonymous]

Thanks, John.

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[Robin]

To add just a bit to what John said, it should not be too difficult to bring the 3rd reef back as well. You will need 2 more mast base turning blocks, 2 spare places in the deck organisers, and 2 clutches, plus the lines will need to be longer (but the original clew line would make a tack line, so needing only one new one).

You might also be able to re-arrange the existing turning blocks, organisers and clutches so that you can use what is already there. For example if the roller genoa halyard is led back, I would switch this to the mast since it is rarely used for adjustment except in benign conditions. Similarly if the topping lift comes back this can be dispensed with (or moved to the mast) by using a rigid kicker system which makes reefing easier anyway.

Good luck whichever you chose.

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[boatmike]

Re: In boom reefing as opposed to the others

Sir,
Your pseudonym seems fairly apt. I am personally attempting to give an unbiased opinion not let off steam........
For your information I am a retired marine engineer and boatbuilder who has spent the last 30 years involved in the design and building of superyachts. I have also been sailing for the last 45 years and have owned and sailed many yachts of from 25 to 45 ft myself with all types of reefing systems fitted. I stand by my opinions which I am as entitled to as you are to yours. The "uncivilised" part of the world I live in is the Solent where very few boats are seen with in boom reefing and an increasing number (I would guess now about 25-30%?) have in mast systems.
I concede this may be different in the antipodes but it's not the impression I get from my many Kiwi friends. And by the way the sail geometry necessary to reef in mast is not the same as in boom where the sail must be cut very flat and stays so. This is not so with in mast systems where a flat sail can be restored to fullness by easing the outhall whether the sail is reefed or not as others have rightly pointed out.
I rest my case.

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[MainlySteam]

Re: In boom reefing as opposed to the others

I am coming to think that you should have my pseudonym.

In fact, tell you what, I'll give it to you and change to using Apoplexy as the pseudonym for myself and then, the next time you get worked up, I can kindly give you that too.

Sorry, but I could never have anticipated that the mere raising of in boom furling/reefing/whatever was so very upsetting to some.

Regards

John

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[Ric]

We have a heavy displacement cruising boat (about the same displacement/volume as a Hallberg Rassy, for example), and I would not wish to have unwanted 20 kg 1/3 way up my mast in sea conditions where the wind conditions meant that the mainsail was completely down/furled.

If you have a boat of say 8000kg, of which about 5-6000kg is ballast in the keel, 20kg up the mast does not make a significant difference. It makes the same difference to the moment of inertia of the boat as having (say) an extra crewman sitting in the cockpit who weighs 100kg, but is a fifth of the distance to the CG. I don't dispute your argument that it is a drawback of in-mast reefing, but I don't think it is particularly significant when viewed in context of all the compromises of security and comfort in a sailing boat, and also of the likely sea condtions that Lemain is likely to encounter in the Med.

I occasionally see people (funnily enough, usually Brits!) cruising the Med in steel flush-deck boats, hank-on sails, no portholes, tiny open cockpit, no bimini, no spray-hood etc. Obviously a very seaworthy boat. But a nightmare to cruise the Med!


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[MainlySteam]

I do not think that you will find there are many non race yachts that weigh 8000kg of which 5-6,000kg of which is in the keel.

I would also suggest that you are incorrect in your comparison between a 100 kg man in the cockpit and 20 kg up the mast.

I = M x d^^2 where M is the mass and d the distance from the centre of rotation.

so a 100 kg man 1 m, say, above the centre of buoyancy and on the centreline of the boat has an I = 100kgm^^2 (about the boats longitudinal axis)

assuming the mast is 15 m high (say around 40 foot boat) above the boom and the 20 kg mass is 1/3 the way up that and the boom is just 2 m above the centre of buoyancy then the I of the 20kg mass is 20x{(1/3 x 15) 2}^^2, therefore I = 980kgm^^2

So you will therefore see that 20 kg up the mast actually has an I around 10 times that of a large 100 kg man sitting in the cockpit (assuming he is on the centreline of the boat).

If one assumes that he is 1.5m away from the centreline (sitting inboard of the lifelines say) then the contribution from that to his extra I is 100 x 1.5^^2,
that is another 225kgm^^2 giving a total of 225 100 = 325kgm^^2 if he is 1 m above the boats centre of buoyancy and also on the rail.

So a 20 kg weight 1/3 the way up the mast contributes to the boats I (about the longitudinal axis) about 3 times as much as a 100 kg man, on the rail. It is a very significant contribution to MOI, as it is about the same as having three 100 kg men inboard of the lifelines (crew are in fact normally taken as averaging around 80 kg so a better comparison would be approaching 4 crew members at the rail).


I find the reaction to my initial asking if people have considered in boom furling to be very strange. I really do not wish to waste my time defending it because as I have been at pains to point out I myself would not have either of in boom or in mast on a small vessel. There certainly seems to be some sort of closedness of minds from some towards in boom furling and when that is the case discussion is pointless.

I trust, however, that the original poster has had some value from the comments.

{Edit : Ric, it may have been that you meant in your post to say "stability" not "moment of inertia" - the above is, of course, referring to moment of inertia but that was the concern I raised in my previous post regarding stability in seas, not static stability.}

Regards

John

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[boatmike]

Re: In boom reefing as opposed to the others

No I am quite happy with the name I have got thank you! It is not talk about reefing systems that upsets me it is your attitude that people who express an opinion are "shallow" and "dissmissive" or live in an "uncivilised part of the world".
Enough! Those who read these posts will take comments as they see them.
Enjoy your sailing!
Mike

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[ChrisE]

Gawd, have we finished this thread now?

I have found this thread very informative and in sum, we have the following:

1. Modern in mast roller furling now seems to be OK
2. Lots of positions to be taken from no-furl to pro-furl (geddit?)
3. Lines led back are liked by many.

Seriously, my original reply concerning in-mast was based upon the assumption that in-mast meant just that, the sail is furled into a slot on the mast. If this is the case then I hold with my original argument, if it gets stuck within a container then you'll have a job to get at it to sort it out. If the furling mechnism is on roll behind the mast, not dissimilar to genoa furling then, I can see that this is both a sensible and safe option. Incidently, IMHO, a genoa furling system that uses an enclosed drum, such as Harken from memory, has the potential for more problems than an open drum system such as Profurl.

Regarding lines led back, these seem fine to me if you have some light flyaway thing with a wopping great, untamable main, like Robin (only kiddin') then you'll need every bit of help you can get. If like my old Rival you have a main the size of decent serviette then going for'ard provides fun on an otherwise dull cruise.

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[cynthia]

Re: Gawd, have we finished this thread now?

I doubt that this will be the last word, but I'd like to put the female viewpoint! We have an in-mast (Easyreef) system, with a fully battened main. Over the three years we have used this system it has been trouble free and reliable. As there are usually two of us on board, I do my stint on watch. Night passages in particular, are made much easier for me because we have everything coming back to the cockpit and the in mast furling system makes it simple and safe for me to reef or increase the sail area as necessary.

If it is necessary for me to go up on deck to change sail I'll do it, but not totally willingly in rough weather! I've seen a forlorn boat in a marine which was brought in by the lifeboat without her skipper who had gone overboard whilst reefing a sail - a poignant sight.

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[Robin]

Penultimate post??

Untameable indeed! We had slab reefing at the mast on our old Westerly 33 Ketch, but with the mizzen & roller genoa rarely had to reef the main in practice. The 1st reef was to drop (or not put up) the mizzen, which was in the cockpit. 2nd reef was rolls round the genoa, by now it is quite breezy, any more and you could drop the main and raise the mizzen again, an easy cheats rig.

The current sweet sailing ocean greyhound has a big masthead rig and with no mizzen the mainsail reefing is used a bit more often. Now, accustomed as I am to sailing in carpet slippers and with a positive hatred of wet oilies, boots and harnesses, something had to be done to make reefing easy and quick but without losing the superb light wind performance. We already had halyards and lines coming back with coachroof self-tailers & clutches, mostly for the genoa halyard, kicker, spinnaker up/downhaul and even for the staysail sheets (we can be cutter rigged too with inner stay & runners), but the main was reefed at the mast with the bum fitted in the standard granny bars. So for us it was not difficult to revamp the lines led back with 3 separate tack reef lines, 3 clew reef lines, main halyard (swapped with the old genoa halyard), kicker and so on. Our fully battened mainsail is hoist on proper roller bearing track cars so is free running both up and down, no winch required except for final tensioning. Reefing now therefore is a simple operation even singlehanded and it is just as easy to shake a reef out, which means that we are not tempted to struggle on with too much sail or even to continue with too little as the wind drops. Unlike with single line reefing there are no blocks/tracks inside the boom to jam, our clew lines just run straight through. The tack lines just go straight from the cringles through a lead on the mast, then back as the others, also nothing to jam and no winch is necessary (though one is available) to pull these in since with the halyard eased they are not under any load during reefing.

My experience of in-mast is very little, other than having sailed boat for boat against another W33 that had it - he was left quickly behind, but that of course could have been my superior skill.... However when we tried an Oceanlord we thought of buying that had in-mast, it jammed on trying to set it (by the owner not me) and there was even a photo in YM of one with the same problem, also on an Oceanlord. It seemed that the leech had stretched and tended to 'curl' and had jammed in the slot half in half out, not my idea of fun on a wet and windy night! I agree that the newer vertical battened in-mast sails at least in part address the problem of lost area but again it still seems to me they could add to the risk of a jam. The analogy to roller reefing is partly correct, but there are additional ways for in-mast to screw up, a) by the leech curl jamming as we witnessed b) by a full length fold forming and being rolled in as the sail is put away, we have seen this done too. Also there is a chance with a roller genoa of rolling a half out jammed sail, either by going in circles or by physically manhandling it to wrap it round, or securing it with a winded round spinnaker halyard. There is little you can do with a jammed in-mast main.

All this is MY personal feeling, as SWMBO says different strokes for different folks, plenty of my friends have other favoured systems they swear by (or at).

PS is yours the Rival Spirit that used to be in our club at Poole?

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[HaraldS]

Re: Penultimate post??

Must say that I'm puzzeld by all these jamming sails. I have sailed a few charter boats which had in-mast furling and they never jammed. They shure had poor sail shape, but these were without any battens. But jamming they never did. Once we broke a worn out reefing line and had to rethread it. It was one of those that wind the reefing line around a drum with grooves below the gooseneck.
Our own no has a massive gear and can either be turned by a winch handle at the mast or via a circular line to the cockpit. The later is the only thing that has shown any wear and I replaced it a year ago. We have now used the sail for 8000 miles in all sorts of conditions, it never jammed, and I can't image how it should.
Our own setup also has tri-radial cut and vertical battens, and the sail can be tuned very nicely, reefed or not via the hydraulic backtstay and baby-stay. Boat goes to windward like crazy, and we just sailed the whole distance from the Canaries back to Portugal against preveiling F6 doing a 170 miles per average day. Sorry, I Cant see the problem your are all mentioning.

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