In mast furling pros and cons

[Tranona]

Frankly I'm astonished that your main weighs in at 14kg. Mine - on a smaller boat - is heavy enough that when bagged I have difficulty lifting it over the guardrails and onto the pontoon.

Presumably there's also a furling spar (a mandrel?) running up the mast as well, which will also weigh something.

A standard furling main has no battens, no slides, no reefing gear etc - just a plain piece of sail cloth. The main on my boat feels lighter than the genoa.

This "extra" weight aloft is only relevant with an add on system on a boat that was not designed for in mast. If the boat was designed for in mast then the design would take into account the weight of the mast and sail. The section of the mast on my boat is smaller than others on similar size boats.

 

[NormanS]

Every week, in the press, you hear of yachts being capsized due to the weight of their in-mast furling gear.
Seriously, the weight aloft will have some influence, so the system will be more suited to some designs than others. For out and out racers, it's not suited, but then they wouldn't want it anyway. For the average cruising family yacht, it's a fantastic piece of kit, and is gradually overcoming the initial resistance to change, just as furling jibs have done.

 

[Cruiser2B]

What would we do if it ever failed? Take a spare halyard and wind it round the mast to stop it flogging and sort it out at our leisure.

Do you not have shrouds and spreaders? How do you wrap the sail around the mast?

 

[silver-fox]

Do you not have shrouds and spreaders? How do you wrap the sail around the mast?

Yes, I do have shrouds and spreaders, suggest you re-read my post and and note that it is the spare halyard that will be wrapped around the mast not the sail.

Obviously the halyard can only be wrapped around the mast below the lower spreaders without climbing the mast but

a) the most likely scenario for a jam is with much of the sail rolled so that would not be an issue.

(b) Even in the event of most of the sail being out it will take care of the main body of the sail (they are triangular on a Bermudan rig) and would certainly enable the the leech to be pulled in tight against the mast.

(c) If the jam did occur with all of the sail out then it can simply be lowered.

 

[silver-fox]

Sorry but weight is a factor and will be measurable both in terms of statis stability and moments of inertia.

Weight will increase over a conventional mast due to a) increased cross section to compensate for discontinuos cross section, b) in-mast furling masts are not tapered as conventional masts, and c) furling gear.

Whilst I've not found anything that provides exact comparison, websites suggest a 60% increase in weight. This is supported by reckmans weights for various inmast and conventional mast weights.

So a 17m mast could easily be 50kg heavier than a conventional mast. This will be acting around the middle of the mast, so probably some 10m above the CG of the vessel; that's the equivalent of a 1/2 ton righting lever. So it will have an effect on stability and handling characteristics of a yacht.

Perhaps there is another naval arch on here who has time and access to data who could do a comparison for use to quantify the effects?

My point is weight does play a factor.

As you will see from my previous posts I have in mast furling. I'm not for or against it. there are pros and cons to it which need to be balanced. In-mast will suite some people, but not others and as such it is an emotive subject!

I take your points absolutely, particularly about mast construction and weight and would like to add a few of my own; -

1. Weight aloft is often used as a criticism of in mast furling but the same criticism is rarely if ever applied to
- genoa roller reefing,
- cutter rigs, (additional forestays and backstays)
- on mast vertical pole storage,
- Gaff rigs
- two masted rigs with all the additional weight aloft,
- or high aspect racing rigs with taller masts and more cross trees.

2. Additional weight aloft does not necessarily equal reduced stability. Yes the righting forces are reduced but inertia is increased, In the days of commercial sail an old dodge, to inhibit rolling, was to haul water barrels aloft which changed the natural frequency of the vessel's roll.

3. As you say most designs are a trade off between benefits and disadvantages and that of course applies to in mast furling. What baffles me is why the disadvantages are exaggerated to such an extent - as you say it appears to be an emotive subject.

 

[JumbleDuck]

Could someone who knows how these systems work enlighten me ... what holds the luff of the sail in place? I envisage a long thin roller up the back of the mast, round which the sail winds, as on my headsail furler, but what keeps it straight when the sail is under tension? Does it simply pull back against the slot and in that case can you reef with the sail drawing?

 

[Tranona]

Could someone who knows how these systems work enlighten me ... what holds the luff of the sail in place? I envisage a long thin roller up the back of the mast, round which the sail winds, as on my headsail furler, but what keeps it straight when the sail is under tension? Does it simply pull back against the slot and in that case can you reef with the sail drawing?

Exactly as you described. A mandrel similar to your roller furling foil which is tension by adjustment at the bottom end. You can find details of construction and setting up on the Selden website. Correct set up is important to trouble free operation, but not difficult and once set up does not needed any change. Clearly works as you can adjust the draught of the sail with the outhaul whether fully or partly out.

 

[NormanS]

Could someone who knows how these systems work enlighten me ... what holds the luff of the sail in place? I envisage a long thin roller up the back of the mast, round which the sail winds, as on my headsail furler, but what keeps it straight when the sail is under tension? Does it simply pull back against the slot and in that case can you reef with the sail drawing?

Just think of the roller inside the mast, as a foil for furling the jib/genoa. That should answer your questions. Rocket science, it aint.

 

[JumbleDuck]

Just think of the roller inside the mast, as a foil for furling the jib/genoa. That should answer your questions. Rocket science, it aint.

So do you have to head into wind (or ease the mainsheet) to reef or can you wind it in with the sail drawing?

It's very unfashionable now, but I really liked the roller reefing boom on my last boat. Dead easy to use, and I could reef from the companionway.

 

[doug748]

I didn't want to hijack Robins thread so I thought I would ask in a new one for the pros and cons of in mast furling.

My initial thoughts are that its not a good idea.................

How could you think that? All the key points have been addressed.

A roller furling main has less windage on the mast and will not jam unless you are an idiot or an Olympic helmsman. If by some act of sabotage it did jam, you could tame the sail by wrapping a halyard around it. The extra weight aloft is "not relevant" and the rig can be as fast as the standard item. Seems pretty clear to me.

Now where is my cheque book.

 

[NormanS]

So do you have to head into wind (or ease the mainsheet) to reef or can you wind it in with the sail drawing?

It's very unfashionable now, but I really liked the roller reefing boom on my last boat. Dead easy to use, and I could reef from the companionway.

You don't necessarily have to be head to wind, but if there is any wind, you do have to ease the mainsheet.

I had boom roller reefing on a Folkboat, many years ago, and while it was good for taking in a reef, (I had a shaped boom), in-mast furling/reefing is streets ahead. it allows to deploy as much, or as little sail as you like, so now I often anchor under sail, by just winding away sail, as I approach the spot.

Just think of it as being very similar to foresail furling, which most will now consider acceptable.

 

[Hadenough]

We are two up, livaboard, ketch rigged cruisers. Without in mast, on both masts I'd be following the mobo forum.

 

[JumbleDuck]

If by some act of sabotage it did jam, you could tame the sail by wrapping a halyard around it.

Could you talk me through that, as I am having difficultly visualising it. I try to furl the main and it jams with 3/4 of the foot still out - what do I do with a halyard to solve the problem? Does it work in F8?

You don't necessarily have to be head to wind, but if there is any wind, you do have to ease the mainsheet ... Just think of it as being very similar to foresail furling, which most will now consider acceptable.

Many thanks - that's very clear. I've had a couple of occasions where odd gusts as I have been furling it have left strange creases and bulges in my jib, but that doesn't a have a slot/groove to jam in, so it seems a bit less serious. Even so, I treat and view the jib system (Sailspar) with a certain caution.

 

[Tranona]

How could you think that? All the key points have been addressed.

A roller furling main has less windage on the mast and will not jam unless you are an idiot or an Olympic helmsman. If by some act of sabotage it did jam, you could tame the sail by wrapping a halyard around it. The extra weight aloft is "not relevant" and the rig can be as fast as the standard item. Seems pretty clear to me.

Now where is my cheque book.

Glad the penny has dropped at last. Hard work sometimes!

 

[NormanS]

Could you talk me through that, as I am having difficultly visualising it. I try to furl the main and it jams with 3/4 of the foot still out - what do I do with a halyard to solve the problem? Does it work in F8?

I've never had a serious jam with mine, but bearing in mind that you are dealing with a loose-footed sail, I suppose if it jammed ¾ out, you would slacken off the out-haul, and then wind a (spare) halyard round it and the mast, to keep the sail close to the mast, until you were in a position to sort it. I've never had to do it, but if I had to, then yes, I would be able to do it in a F8. I do have a spare main halyard. My main is not very big, on a 36ft ketch. (The mizzen has lazy jacks, and a stack-pack, and normally takes two of us to hoist or drop, while I normally do the main myself.)

 

[JumbleDuck]

I've never had a serious jam with mine, but bearing in mind that you are dealing with a loose-footed sail...

<lightbulb illuminates>

D'oh.