So walk me through the in-mast furling mainsail

[Muaddib1116]

Yeah, I wonder as well. As far as cost, that seems like the most likely reason, but it also seems that IMF would be more expensive than IBF. You need a purpose built mast vs a purpose built boom. Which is another advantage of IBF, it's easier to adapt to or from a slab reefing system, by just changing the boom. Interestingly, when you look at the much larger sailing superyachts, >100ft, they seem to favor IBF. I wonder if the weight aloft of IMF becomes too untenable if scaled up.

[S/V Illusion]

Originally Posted by Muaddib1116

Yeah, I wonder as well. As far as cost, that seems like the most likely reason, but it also seems that IMF would be more expensive than IBF. You need a purpose built mast vs a purpose built boom. Which is another advantage of IBF, it's easier to adapt to or from a slab reefing system, by just changing the boom. Interestingly, when you look at the much larger sailing superyachts, >100ft, they seem to favor IBF. I wonder if the weight aloft of IMF becomes too untenable if scaled up.

In our case, we went from a boat with an aluminum mast and mast furler to a boat with a carbon mast and boom furler. Night and day differences in terms of reliability, ease of use, less weight aloft, performance, etc...

Where the mast furler usually worked fine, it took careful and deliberate precautions for that to happen and the sail shape despite vertical battens was terrible and seriously limited roach.

[George_SD]

Beneteau with in mast furling here. Yes, I've had some issues, but honestly they are due to age of the sail, hardware, lack of proper maintenance. If everything is maintained - it works great, just like traditional sail setup.

I have two friends with newer Beneteaus (50ft and 35ft) - their furling mains work great and are much easier to handle than traditional in my view. Everything is done form the cockpit by a single person - putting it up/down, reefing, etc.

Can furling main jam? Yes, just like the mast cars on a regular main if not maintained. One additional benefit of the furling sail is that it can last longer because it is protected by the mast when not in use.

There are advantages and disadvantages to both, just pick what would you rather deal with.

[Camille1]

In boom every time. Better batten control. Better sail shape. Any bad trouble? Let go or cut the main halyard! Although in all my miles I have never had to. If in doubt, furl.
I use the halyard and winch as I think the power of direct hydraulic or electric could cause serious damage especially in an emergency situation.
Good wishes.

[Markb250]

There seems to be little discussion here about the substantial compromise to sailing performance that comes with the substantially compromised sail shape inherent in the in mast furler concept.
Just look at an in mast furler and a fully battened slab reef main sailing side by side, and ask yourself why you would want to completely stuff up the most important asset you have, when slab reefing just couldn't be any easier and reliable than what it is.

[89zorro89]

I have an in-mast furler and it works beautifully. I've never once had an issue with it. I never hear any noise from it or any wind whistle. Perhaps its the specific design of the in mast slot. I try to always keep light tension on the clew with the outhaul and never furl it in all the way. I always leave a balance of sail of about 16" hanging out. The only reason I would switch to an in-boom furler is to bring the weight of the sail down lower when furled for better boat handling.

[Muaddib1116]

Originally Posted by Markb250

There seems to be little discussion here about the substantial compromise to sailing performance that comes with the substantially compromised sail shape inherent in the in mast furler concept.
Just look at an in mast furler and a fully battened slab reef main sailing side by side, and ask yourself why you would want to completely stuff up the most important asset you have, when slab reefing just couldn't be any easier and reliable than what it is.

I think they've definitely been brought up here, as well as in every other in-mast furler thread.

[Muaddib1116]

Originally Posted by Camille1

In boom every time. Better batten control. Better sail shape. Any bad trouble? Let go or cut the main halyard! Although in all my miles I have never had to. If in doubt, furl.
I use the halyard and winch as I think the power of direct hydraulic or electric could cause serious damage especially in an emergency situation.
Good wishes.

On paper, I definitely like in boom furling, and I probably would like it in reality. But I thought there was a decent chance I might dislike the in-mast system, and I don't. In fact I like it quite a bit so far. And so do lots of other people. If the OP is contemplating buying a boat with an in mast furler, I don't think he should be put off by it. It seems like each of the systems can work well with proper use and there is probably a long list of things that should rank higher when deciding on what boat to buy.

[AiniA]

Originally Posted by S/V Illusion

To state the obvious, any slab reefing or dousing a traditional mainsail can easily be done from the cockpit when properly designed to do so. The argument that it’s more convenient to reef an in-mast furler applies only when the owner allows a rigging arrangement to necessitate going on deck. Kind of ironic in a debate about convenience.

I think we can gone through this more that a few times but here goes again. First, I can only talk about a Hood furler on a Bristol 45.5. Also we had no battens and most of our experience was off the wind in the trades. We did a bit more than 40,000 nm with the rig, mostly with an 'experienced' mainsail that got more experienced with time. We had one slight jam which took about 20 minutes to get out - carefully in and out. If you are to get a jam it will be unfurling if you unroll too much sail inside the mast cavity without keeping enough tension on the outhaul. Someone mentioned a series of requirements for furling. We started with a similar list but came to realize that the tack and the angle do not matter. Just push the button while keeping the outhaul snug around the winch so you get a tight furl. Don't know other makes but with the Hood you could take the sail and its foil down if it was jammed. Not a casual undertaking but possible.

For extended cruising we found it tremendously useful. There are times you want to have equivalent of seven reefs in and you can do it. Great for balancing the boat for the Monitor. We had a trysail (separate track) onboard but never thought about using it, even in the very windy bit from Mauritius to South Africa. Putting a reef in took one minute or less while sitting in the cockpit. I wonder if critics of in-mast mains have significant personal experience with them? You hear of lots of people going from traditional rigs to in-mast and loving them - I did 40 years with regular ones. Very few people start with in-mast and go back. When we bought our boat I was skeptical. A sailmaker said you can bolt a Harken track (for batt-cars) over the slot and go conventional. After my first offshore passage I never considered the possibility again.

Bad parts? You do lose sail area. For trade wind sailing not an issue. And ours, and other Hood units, do moan like crazy, but only at a dock and only if the wind is around 135° from the bow. We had a 'flute stopper', a piece of stiff sail cloth with large buttons every 18" or so that we hoisted up a flag halyard. Worked great, should have been called a tuba-stopper since the note generated was quite low.

[JPA Cate]

Hi, dmk sails...yet another opinion. If you have a large laminate sail, maybe you'd also go with an inmast furling. Our main is spectra, and somewhere between 500 and 600 sq ft. in area, so it is a largeish sail. We have slab reefing, three reefs, and I would not want inmast furling.

Someone above wrote that in mast furlers are very much better now, but I've seen people losing time in marinas while riggers made money off them trying for hours to get one un-jammed. How I feel is that I would rather not have to cope with having a situation develop where we could not recover from it unaided. We are both over 80 yrs. old. When you have a boom bag with lazy jacks to drop the sail down into, it is immediately under control, and it cannot jam. One also avoids the optional expense of the gear. What's to not like?

You wrote, "Just treat me like an 8-year-old, spell it out for me, and tell me that once I have an in-mast furling mainsail, I'll never go back." Nope, sorry. At least for me, the downsides I've seen over the years have really turned me off them.

Ann

[shimari]

Originally Posted by Muaddib1116

Yeah, I wonder as well. As far as cost, that seems like the most likely reason, but it also seems that IMF would be more expensive than IBF. You need a purpose built mast vs a purpose built boom. Which is another advantage of IBF, it's easier to adapt to or from a slab reefing system, by just changing the boom. Interestingly, when you look at the much larger sailing superyachts, >100ft, they seem to favor IBF. I wonder if the weight aloft of IMF becomes too untenable if scaled up.

I don't remember the details, but I believe you need a new sail and some track work done on the mast. It's not as simple of a replacement as it seems.

[lyl]

Originally Posted by DMF Sailing

I wanna know what love is...
I want you to showwww me....

...love for in-mast furling mainsails, anyway.

I've sailed a lot of different kinds of cruisers, but never one with in-mast furling mainsails.

What do you do if it gets stuck just before a squall? Is there a way to drop it?

Also, is that an outhaul in my attached picture? I know what an outhaul does (I often sail racers) but how does that come into play here?

Also, I'm trying to work out vertical battens.

Just treat me like an 8-year-old, spell it out for me, and tell me that once I have an in-mast furling mainsail, I'll never go back.

Whose idea was this poll?!

[Muaddib1116]

Originally Posted by shimari

I don't remember the details, but I believe you need a new sail and some track work done on the mast. It's not as simple of a replacement as it seems.

Yeah, that's true. I suppose it might be possible to adapt the sail, but you definitely need a new track.

[Fullbore]

Similar to furling head sail questions 4 or 5 decades ago...

[rickpyne]

Before you move to an In Mast furling system , firstly look at mailsail shape and methods of optimising shape for some sort of performance, secondly ask owners of IMFurlers how many times they have experienced jams, thirdly how many times the system has failed and produces full sail when you experience heavy winds when fronts go thru and when under load the middle of the sail pulls to the stern, bending the RFsystem [halyard and sailtrack] and pulling it out of its bearings inside the mast. Try and fix that when your at sea.