Seriously, why do people like in mast furling?

[SteveSadler]

Dale, you asked about furling by hand. By myself, no, but my wife and I together, or the 2 girls together, yes it's quite easy. It needs to be on a stbd tack, one wrap for the outhaul for tension. full of wind downwind, no, I winch it.

[glynhome]

It seems to me that some of the hardened views against IMF are not recognising the advances made by mast and sail designers in recent years. I have Elvstrom cruising laminate sails with vertical battens that are specifically designed for use with my Selden IMF.

In 5 years using this set up sailing around the Adriatic I've never had a jam in or out, in sudden squalls and even more sudden Bora the main is reefed or away in seconds, to me furling and unfurling just seems like common sense, what's not to like? She that shall be obeyed wouldn't fancy the effort of slab reefing anyway, looks like hard graft.

[Pete7]

Originally Posted by Jim Cate

Ahh, come on, Pete!

Originally Posted by Jim Cate

Reefing: DH feels that a slab reefed sail has poorer shape than an IMF reefed sail. I disagree, for my observations show that the shape is good in all three reef positions...

I don't think he said that, but said that the centre of effort is better placed nearer the mast which is just what you want as the wind increases.

Originally Posted by Jim Cate

Mine has the advantage of being behind a slimmer mast section, and that is an obvious advantage over the fat mast section of an IMF rig

I haven't studied larger yachts but there is no noticeable difference in cross sectional area comparing my mast with an identical slab reefed Moody.

Originally Posted by Jim Cate

Importance of performance, and the loss thereof: You say that when you hoist the sails and trim them you are at or near hull speed. I suspect some exaggeration here, unless you are always sailing in F4+ on a beam reach.

Certainly the F4 is pretty close to the mark.

Originally Posted by Jim Cate

Then you say that you are happy to have a 1 or even a 2 knot loss of speed from your IMF main.

No i didn't say that or want to imply it, I was trying to quantify your comment about "severe loss" as something that could visualised.

Originally Posted by Jim Cate

So there you go... for my boat and my sailing style, the difference in performance is important. I'm not trying to talk anyone out of their IMF, for I understand the appeal. It just isn't for me, right now, doin' what I like to do. Oh, BTW, I already have the fancy folding prop...
Jim

Equally whilst I would be happy to demonstrate IMF to someone who hasn't used it before warts and all, I wouldn't try the hard sell. Happily I have just found out my VP 2003 gearbox can run either left or right hand, that opens up the possibilities for a second hand folding prop enormously


Pete

[David B]

Originally Posted by donradcliffe

The furling masts used to scream like banshees in marinas when the wind came round from the back or sides. Have they fixed that, or do all British marinas sound like berserk pipe organs??

Our Selden system never screams, and we have spent a lot of time in high winds. In a marina, we hear other yachts halyards making a racket (and damaging their owners boats, and when it really pipes up, then of course there is the rigging screaming from various boats around us.

[Kestrahl]

We have done sails for many different systems and they all more or less worked ok. The retrofit on the back of the mast systems are the least favorite as the sail has to be well under built to fit inside. Using good quality dacron or stable material makes a difference to how long it will work well without problems. The shape design also has a big part to play. We see a lot of sails from the low cost sailmakers having problems.
The performance loss is mostly in light airs due to losing area up high, this can be solved with vertical battens but then they create their own problems. The furled shape is not as efficient as a reefed mainsail shape as you are cutting of the front of the foil, rather than reducing the size and depth.

[SecondBase]

As long as you have nearby access to a rigger and a crane furling is a convenience. It is a safer solution for certain while it is working. On the other hand I've had two furler incidents. Both required a rigger back at the dock and one presented risk of injury.

If your focus is self-sufficiency, low cost and Pardey "as simple as possible" then hanks a lot.

Either way can, and does, work so really it is a tradeoff for the OP to ponder. OP the best way to get your own perspective on this is run a couple tests. Take a boat out in 6 foot seas and haul down the hanked on jib and main. See what you think from the bow. Can you do it? Can your sailing partner do it as well?

Then unfurl a sail in 25 knots, tie off the furling line to simulate a jam and reduce sail through another means besides rolling. Compare the two experiences and you'll be ready to choose what is right for your situation, your skill & fitness levels, and your boat.

Finally consider hanked on with a humble downhaul line on each sail run back to the cockpit.

[Oceansailor]

Why are people buying in-mast furling?



Because it is the most comfortable system for a shorthanded crew. If a couple in the age +60 wants to go offshore cruising in a bigger yacht 45 – 70 foot there is no better alternative than in-mast furling.



IMF gives you the opportunity to effortless reef your sails in all conditions in matter of seconds. This without leaving the cockpit.



It was a success on bigger high end offshore cruising yachts like Amel, HR, Najad, Discovery, Oyster, Hylas etc. Their typical customer is a couple +55 that wants to do some long distance cruising.



As it was so successful it soon spread to the charter market and other production boats.



With todays sail technology (laminate sails with vertical battens) in-mast furling is surprisingly fast. I’m sure a a couple on a +45 foot yacht will be faster with IMF than if they have had slab reefing due to the fact that they will sail more balanced at all times as reefing is a matter of seconds.



To take advantage of the better performance of a slab reef main with a big roach on a larger yacht you need more crew than the average cruising couple.



The in-boom furling was developed to make sail-handling more comfortable without loosing performance compared to a slab-reefed main.



In-boom furling never got much traction in Europe as the in-mast furling was already a success.


In-boom has two major drawbacks. You still have to overcome gravity to get the sail up.



But more important it showed quite quick that reefing was not possible at all angles of sails as the mast-boom angle is very, very sensitive. Offshore cruising is most of the times running with the wind. In-boom is more or less impossible to reef downwind in a 30 knot blow.



Performance are not as good as a slab reefed main as the shape has to be compromised to get the sail in to the boom. Also the lack of outhaul when reefed did not help.



In-boom systems are to my humble opinion not an optimal offshore system for a shorthanded crew. It has it place on larger yachts with a professional crew with technology to control boom angle, or on boats that do coastal sailing. I have tried several in-boom systems, Leisurefurl, Sailtainer, Hood. They all struggled in above mentioned areas.



I think all systems have their advantages. It very much depends on your type of cruising what system will make the crew happy.



When the OP understands that the typical buyer for +50 yacht that wants to go long distance cruising is in the age +60 and do not want to have blood taste in his mouth after reefing he will be a successful boat salesmen.

[waterman46]

Ok, I am now convinced that my earlier claim that I really enjoyed slab reefing at the mast in the dark when its cold and blowing like stink, was simply prompted by jealousy.

Thing is I have a boat whose value wouldn't justify replacing her mast completely. I think I have seen some mains set up with roller reefing and furling similar to a Genoa jib
Obviously there would have to be a very taught wire
strung on aft side of mast, which could cause some mast bend but could probably be offset by aft Tdx lower shrouds. Has anyone here seen or used such a rig?

[Pete7]

Originally Posted by waterman46

Ok, I am now convinced that my earlier claim that I really enjoyed slab reefing at the mast in the dark when its cold and blowing like stink, was simply prompted by jealousy.

Thing is I have a boat whose value wouldn't justify replacing her mast completely. I think I have seen some mains set up with roller reefing and furling similar to a Genoa jib
Obviously there would have to be a very taught wire
strung on aft side of mast, which could cause some mast bend but could probably be offset by aft Tdx lower shrouds. Has anyone here seen or used such a rig?

Sounds like you are inventing one of those after market types which seem to collect poor reviews. I wouldn't change a mast either, if you have slab reefing and it works just keep it.

[double u]

"the centre of effort is better placed nearer the mast"
gentlemen, youall should have paid more attention in your geometry-lessons...the center of effort is exactly in the same spot, only the center of gravity is different...

finally a very valid argument:
"a boat whose value wouldn't justify replacing her mast completely"

[double u]

Originally Posted by Martkimwat

Can anyone show me an example of a racing yacht with in mast reefing? if not, one has to ask why not.

wouldn't want an imf myself, but...I cannot resist...
http://c8.alamy.com/comp/H9AH15/ajax...ded-H9AH15.jpg

he won the OSTAR too, u know...

[Pete7]

Originally Posted by double u

"the centre of effort is better placed nearer the mast"
gentlemen, youall should have paid more attention in your geometry-lessons...the center of effort is exactly in the same spot, only the center of gravity is different...

The centre of effort of a main sail moves towards the mast as an in mast main is reefed.

Peter

[double u]

...as it does if you reef "downwards"...

[Dockhead]

Originally Posted by double u

...as it does if you reef "downwards"...

Correct. An in mast furling main reefed to x% looks just like a slab reefed main reefed to the same %.

As Double U correctly stated, the only difference is CG.

The shape might be different, since different parts of the sail are used in each cases. When you reef an in-mast furling main, the bottom part of the leech and outer part of the foot remain in use while the top part of the leech and forward part of the foot disappear into the mast. With slab reefing, the top part of the leech stays in use while the bottom part gets folded up with slabs taken out of the foot. But the resulting triangle is the same shape (in two dimension, if not in three), in the same place, with the same CE.