In mast furling vs slab reefing

[Robin]

Re: Penultimate post??

Hi Harald

I suspect your sails are in better condition! The one which jammed on our demo was 13 years old and the sail that came with the boat when new, solid but badly stretched. I think the other type of jammed fold is caused by faulty technique furling the sail, I haven't seen how it was done, only the result, but I would imagine you know much better how to do it properly. As I said, I have a lot of friends with in-mast who like it, so it is just a personal choice for me not to, mostly though because of the loss in light wind performance.



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[Ric]

I'm still not convinced that in-mast furling makes a significant difference to the roll moment or stability of a typical modern cruising boat with high ballast ratio, high coachroof, smallish mainsail (compared to genoa) and high and relatively short boom (such as Lemain is looking to buy). Granted, it makes a difference - but not enough to dictate choice of rig. Even with slab reefing, when the sail is down, the mass of the sail is considerably above the CG of the boat. I'd agree that with in-mast furling the CG of the furled sail is even higher, one third approx of distance between boom and mast head. But given the height of the boom above CG of a typical cruising yacht, the proportiional increase in lever moment of in-mast is less significant than one might first imagine when calculating static stability. Now calculate dynamic stabilty - the disadvantage is even less because as you point out the roll inertia is proportional to the square of the distance so you need to do a bit of calculus over the triangle of the sail. A bit complicated to explain here in text but very simple with a diagram and pen and paper. I put in a few guesstimate figures based on the specifications and stability curves of my boat (provided by Jeanneau) and it made negligible difference.

I'd agree that the difference is significant on a racing yacht with low freeboard, flat deck, a relatively low ballast ratio and very large mainsail on a full-length low-slung boom.

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[Talbot]

I agree, if you look at the weights involved, there is actually very little difference in righting moment to putting a 18 -24" radar scanner 2/3 up the mast and lots of people do that without concern. The only jams I have had are in hauling out the sail, when the line doesnt follow the roller down the cylinder at the bottom of the mast, but jumps above the rest of the rope. All that is needed to untangle is to heave it out again (and I have a dedicated small winch just for that task).

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[MainlySteam]

Re: Gawd, have we finished this thread now?

Gawd, I hope so too, Chris!

However, I am at pains to point out that all I have done was earlier on asked why people were not commenting on in boom furling. The only response that got was along the lines of "RUBBISH, RUBBISH, RHUBARB, RHUBARB" all from peeps with in mast furling, which type of response usually means that they haven't a clue what they are talking about.

Some points were raised (some based on reefing systems of nearly half a century ago!) and I endeavoured to respond to those out of which all the mast furling peeps seem to imagine that I am some sort of boom furling ogre despite my pains to point out that I would have neither for my personal use (and so have no personal preference for either) and that they both have problems.

I am used to specifying high quality boats, mainly for commercial customers, and I specify what is appropriate to the particular service - there are always alternatives, all with their pluses and minuses. As you say Chris "Lots of positions to be taken from no-furl to pro-furl (geddit?)" - not sure if the "geddit" is aimed at me, I trust not, but it seems that in the minds of many in boom is a rubbish position. Apparantly in boom Furling/Reefing/Whatever is a dirty word in some forumite mast furling circles.

Ric, I respect your comments and have some sympathy with what you say, and I value, as always, Robin's comments. Many, but not all, of the rest have been basically along the lines "I have in mast, so there, in boom is rubbish!" - sad and narrow in my view.

Farewell and happy reefing (but not the ones you smoke!) to all.

Regards

John


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[alant]

Sailed on a boat with a New Zealand designed in boom system - with all lines back in cockpit. (Think it was called Rotofurl). Excellent. At least any main still up, could be tamed in extremis. main was fully battened, with good roach.
However, as with both in-mast or in-boom, the attitude of the boom is critical, all lines should be marked at any spinlocks, otherwise furled sail will jamb inside the mast or at very least, be extremely difficult to furl or release.

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[ChrisE]

The last post?

Robin, sailing in carpet slippers, can offer you my zimmer?

Mainlysteam, I wasn't getting at anyone with my earlier post, just observing the different points of view.

For what it's worth I don't have strong views about absolutes in this, or for that matter any other technical sailing, area. If it works for you and you are happy with it why change? I beleive that part of the problem of debates like this is that we, inc. me, don't state our crusing grounds or uses for the kit. I like long distance sailing in out of the way, relatively uncivilised places, where bits to repair other broken bits are difficult to get and with my very limited mechanical and electrical skills my preference is always for something that I can mend with 1/2" spanner, a screwdriver and bloodymindedness.

Yes, Rival Spirit used to live in Poole, now rests in Keyhaven prior to her next adventure which this year is to the fleshpots of France.

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[webcraft]

Sailed on a boat with a New Zealand designed in boom system - with all lines back in cockpit. (Think it was called Rotofurl). Excellent. At least any main still up, could be tamed in extremis. main was fully battened, with good roach.
However, as with both in-mast or in-boom, the attitude of the boom is critical, all lines should be marked at any spinlocks, otherwise furled sail will jamb inside the mast or at very least, be extremely difficult to furl or release.

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You are right about marking lines at clutches if you have in mast furling!

I spent a week skippering an Elan 330 in Greece. One lunchtime at anchor there was an almighty bang - the main halliard clutch lever had literally exploded, presumably cumulative UV damage. I rethreaded the halliard through a handy spare clutch, guessing at the tension and realising that the halliard release might cause problems. However, the sail unrolled OK and off we set.

Two hours later, the wind shifted 90 degrees and squalled up to over 30 knots and the sail would not furl. The next hour or so was 'interesting'

I:ve not been keen on in mast furling since then.

- W

 

[Baggywrinkle]

Any reason why this 19 year old thread has been resurrected?

 

[Cariadco]

Trouble is I'd then have to put on the oilies, then the harness and the slippers would have to go too!

Joking apart, for us we have everything back for reefing in one spot, it can then be done by just one person. IMO it is all or nothing, if you have to go forward to hook on a reef, or for the halyard it is better to do the whole job at the mast. Our procedure with every bit led back under the sprayhood is:-

Let go mainsheet
Let go kicker (ours is rigid and supports the boom, no need for topping lift)
Let main halyard down to a premarked position
Pull in reef tack line through clutch, close clutch (winch available but not needed)
Winch in reef clew line through clutch
Re-tighten main halyard
Tension kicker
Re-set mainsheet
Take up loose slack on next reef lines
Drink coffee.

The loose sail sits in the lazyjacks.

We once tried a Westerly Oceanlord with in-mast and the sail would not unfurl, the leech jammed in the slot, probably because the sail was knackered but it didn't help my prejudice against the system.

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Funnily enough, I tighten the Halyard first, and then tighten the reef line.
Wonder which is the best way?

 

[RunAgroundHard]

Any reason why this 19 year old thread has been resurrected?

Because Webcraft failed to use one of his alternative monikers before committing the nefarious action. A rookie mistake or a result of repetitive complacency; who knows!

 

[Clancy Moped]

At anchor, or in port for that matter, in-mast makes you roll more because of the weight distribution.

 

[Tranona]

At anchor, or in port for that matter, in-mast makes you roll more because of the weight distribution.

Do you have any calculations to support this statement?

 

[Clancy Moped]

Do you have any calculations to support this statement?

Nope, just observations and conversations with owners, think about it's an upside-down pendulum.

 

[lektran]

At anchor, or in port for that matter, in-mast makes you roll more because of the weight disstbution,.

I would be interested to see a comparison of two similar boats side by side. The assertion sounds reasonable but actually almost half the weight of the sail would sit in the bottom quarter of the mast.

Based on that I can't imagine it's a dramatic difference between the two.

 

[Clancy Moped]

I would be interested to see a comparison of two similar boats side by side. The assertion sounds reasonable but actually almost half the weight of the sail would sit in the bottom quarter of the mast.

Based on that I can't imagine it's a dramatic difference between the two.

The momentum builds. The boat next to me for a while was a 40ish Gib' Sea, it rolled like hell compared to us. When the sails were taken out for winter, we were on a par.

 

[Chiara’s slave]

Surely the weight of the sail is not the whole picture. The additional size of the mast, and the mechanism itself would be a chunk of the additional weight up there.

 

[Clancy Moped]

Surely the weight of the sail is not the whole picture. The additional size of the mast, and the mechanism itself would be a chunk of the additional weight up there.

Indeed.

 

[Chiara’s slave]

Indeed.

Which of course go all the way to the top, barring maybe a foot.

 

[Clancy Moped]

Which of course go all the way to the top, barring maybe a foot.

Add a nice old Raydome etc.

 

[Fr J Hackett]

I have sailed two boats with Furlboom in boom reefing and they were OK but the angle of the boom was important if not critical when reefing. The sails imo did not set as well as a slab reef of which I have saile more than a few. Not sailed an in mast so anything I say is purely speculative and fueled by my prejudice, I wouldn’t want it on my boat. IMO a well cut single line reefing main with lines led back to the cockpit is unbeatable, there is no reason that it can’t be handled by a single hand sailor, I have on boats up to a 50 foot Valiant.