Traditional Main vs In-mast Furling

[tp12]

Originally Posted by tp12

I'm not blessed with your experience and I mean that genuinely, not sarcastically. I, of course, considered that the sail was stretched and lost its shape. But why should it? Is that just inferior materials or design?

My understanding is that the best performing main is not a roller furler, at all, but a good shape, laminate sail that flakes?

You're one of the people I respect on CF so I will give more weight/consideration to your view

Dockhead?

[Dockhead]

Originally Posted by Kenomac

There's a couple of errors on your Oyster data. Mast height for our 53ft cutter rig is 23 meters or 73ft.

If you say so. The data I posted is from my own comparison sheet I made 8 years ago, and it's possible there is an error in it. I don't have the original spec sheet from your boat with me.

[double u]

wouldn't hull deadrise greatly affect the rollcharacteristic of a boat?

[Kenomac]

Yours has a typo... oops. We ordered new sails last year for our standard Oyster cutter rig. The sails that came with the boat were 15-20% too small, maybe your specs error helps to explain part of that fiasco, which was another oops.

[Dockhead]

Originally Posted by tp12

Originally Posted by tp12 View Post
I'm not blessed with your experience and I mean that genuinely, not sarcastically. I, of course, considered that the sail was stretched and lost its shape. But why should it? Is that just inferior materials or design?

My understanding is that the best performing main is not a roller furler, at all, but a good shape, laminate sail that flakes?

You're one of the people I respect on CF so I will give more weight/consideration to your viewDockhead?

I was attempting to joke light-heartedly -- hope you didn't take it as making fun of your post.

I think if you have to answer the question in one word, then that word would be YES, you are right. Full batten main definitely performs better than in-mast furling one for various reasons which have been discussed.

But the pros and cons of both systems are rather complex, and that has also been discussed pretty thoroughly, in this and several other threads. Both systems have their own good and bad points, and which is better for you boils down to personal taste and also -- where you sail.

Both systems benefit hugely from GOOD SAILS. Best money you can spend on a boat, is on the sails, whatever their type. In-mast furling, particularly, works about a million times better with a good laminate sail, than it does with a baggy Dacron one.

Hope that's helpful.

Cheers.

[Dockhead]

Originally Posted by double u

wouldn't hull deadrise greatly affect the rollcharacteristic of a boat?

Indeed. Read Fundamentals of Yacht Design on that. It's more important than how heavy your mast is.

[tp12]

Originally Posted by Dockhead

I was attempting to joke light-heartedly -- hope you didn't take it as making fun of your post.



I think if you have to answer the question in one word, then that word would be YES, you are right. Full batten main definitely performs better than in-mast furling one for various reasons which have been discussed.



But the pros and cons of both systems are rather complex, and that has also been discussed pretty thoroughly, in this and several other threads. Both systems have their own good and bad points, and which is better for you boils down to personal taste and also -- where you sail.



Both systems benefit hugely from GOOD SAILS. Best money you can spend on a boat, is on the sails, whatever their type. In-mast furling, particularly, works about a million times better with a good laminate sail, than it does with a baggy Dacron one.



Hope that's helpful.



Cheers.

I didn't take it that way, no worries.

I have experience in some areas, a lot of theoretical knowledge in others and zero clue in the rest!

If we were to take a racers view and consider performance as valuable above all else then I think you'd choose a good, laminate, full batten, fat headed main on most cats.

When you weigh other factors, such as convenience, then the choices open up and include furling.

It's worth noting that Kato, a 20m Schionning performance cruiser design, was specced with a furling boom! From reading the article discussing it, it appears to address the sailing performance and weight aloft issues while adding the furling convenience for reefing etc

[tp12]

I'm still of a mind to just have a traditional, full battened, fat headed main for simplicity's sake and have all the headsails on a furler.

This is for a stretched Arrow 1360 design

[UNCIVILIZED]

Originally Posted by tp12

I'm still of a mind to just have a traditional, full battened, fat headed main for simplicity's sake and have all the headsails on a furler.

This is for a stretched Arrow 1360 design

Great! Now think, big, rotating carbon fiber wing mast. That'll power her up nicely. And you can even put battens in your jib; vertical or horizontal. The former for furling sails.

[Dockhead]

Originally Posted by UNCIVILIZED

. . . And you can even put battens in your jib; vertical or horizontal. The former for furling sails.

Thread drift, but what do you think about battens in jibs?

I was curious about this, but my sailmaker discouraged me. What do you think?

[poiu]

Sailing yachts at anchor have less of a rolling problem than similar displacement motor yachts in most circumstances. Bigger sailing yachts with more inertia have less of a problem than small sailing yachts. The difference is quite remarkable in general.

I have a fairly heavy yacht with a heavy mast and can anchor in places that few other boats, sailing yachts or particularly motor yachts can anchor in. Next to the main channel into port, where large motor yachts belt past creating wake for example. A boat wake will slap my side, but will knock a 20ft boat on its side. At sea, the damping from the hull and sails mean resonance is never seen

I think the focus on inertia as a continuum is applying the wrong emphasis on the problem, which should be on establishing resonance. The point is that it is not just about the degree of the problem, it is about preventing it entirely. With high inertia getting the boat into a resonant state is not easy and usually impossible. The higher the inertia the rarer the circumstances where it can happen.

For the few exceptions where it happens, changing the angle of the boat to the waves or a flopper stopper like Kenomac's is a good solution. The smaller the boat, the more it should be needed. I don't know why they aren't used a lot.

[tp12]

Originally Posted by UNCIVILIZED

Great! Now think, big, rotating carbon fiber wing mast. That'll power her up nicely. And you can even put battens in your jib; vertical or horizontal. The former for furling sails.

I'm not sure if you're taking the mick, or not!

On a cat I would imagine a that well cut, furling Genoa would be good. The mono I race on has a similar wardrobe and performs well

[daletournier]

Originally Posted by Dockhead

Great question. I've pondered it myself.

I think one answer is that almost all catamarans are used in latitudes where in-mast furling is not really useful. I have never seen a single catamaran in the North Sea -- not one. I've seen four or five in the English Channel in eight years, and two of those were upside down (seriously). And 99% of large cruising boats have in-mast furling up here.

In the Caribbean, in my experience, probably 50% or more of large cruising boats have full batten mains, and virtually all cats do, and cats are 50% of the fleet.

Also, cats -- for some reason that someone more knowledgeable can explain -- usually have small jibs and large roachy mainsails. They are mainsail-oriented rigs. In-mast furling would be no good for that.

Lastly, without ballast, they probably can't tolerate the weight aloft as well.

Those are my idle, uninformed speculations, anyway, FWIW.

Im in the Seychelles and im blowm away by how many cats there are. Im surrounded by six right now, ive only seen two other monos since ive been here.
And i will admit im very envious of the beautiful roachy, full batterned mains they have.

[daletournier]

Originally Posted by Dockhead

According to the data sheet from your boat (not the type, but your specific boat), your mast is 20 meters high. Is that not correct? Mine is 23, about 50cm higher than subsequent M54's (mine was the prototype).

Other specs:

Oyster 53 M54

Hull length 16.00 16.54

LOA 16.40 16.72

LWL 13.75 14.02

Beam 4.65 4.88

Draft 2.21 2.35

Light ship displ. 22,250 20,060


One thing you're right about is the displacement -- my memory was wrong. The Oyster is 2.2 tonnes heavier, not 4.

The two boats are very similar, but not exactly alike. I was comparing them intensely 8 years ago when I finally bought my boat. There were a lot of things I preferred about the Oyster, including the fact that it was a bit smaller.

I have know idea regarding specs on either of your boats and i certainly cant get as technical as some here. But i feel hull shape and keel play a huge role in how much you roll!

I say this in a completely non bias way regarding my own boat. As you know ive only had her 10mths. Im very surprised how little roll i experience. She has a roller furler and a 55ft large section mast, but also a fat bum and a 2.4m lead keel. She really dosent roll that much and i have definately been subject to ocean swells.

[Dockhead]

Originally Posted by daletournier

. . . But i feel hull shape and keel play a huge role in how much you roll!. . .

Your feeling is shared by the authors of Fundamentals of Yacht Design!

I think they say actually that hydrodynamics plays the by far greatest role in roll behavior.