Cutter rig with square-top, no back stay?

[Beacon Hill Ben]

Hi, my first post, so please be kind, I am a sailor, not a designer. I am looking to spend some hard earned money on a new sail boat: 31'2" hull length, plumb bow and stern, 10' beam, lifting dagger keel, dual transom-hung rudders, very light displacement of 2.25T. No inboard engine but an outboard (yes, I am happy with that, it's a sail boat), no portholes, no thru-hulls. I have a very good NA for the hull design, so no issues there.

The sailing will be single of short handed crew, max crew of four, from Sydney out into the wide open ocean: Tasmania, New Zealand, the Pacific, Asia. Yes, we will have to pick our weather, but we also bring storm sails and a JSD.

It is the rig/mast/sail plan that I have questions about. I want the fastest and easiest rig possible for this light hull. I am open for anything and everything, so I need some help to focus and make up my mind, please.

I was thinking of a carbon mast, preferably rotating/wing profile if possible(?), no backstay or running, textile shrouds/stays where possible, with a square top main (see Pogo 30), but with cutter foresails for ease of handling and trimming (and they look cool), we will have a sprit, and code sails for down wind courses.

Is this possible or am I dreaming? Should I look at some other type of rig/sail plan?

 

[Skyak]

Hi, my first post, so please be kind, I am a sailor, not a designer. I am looking to spend some hard earned money on a new sail boat: 31'2" hull length, plumb bow and stern, 10' beam, lifting dagger keel, dual transom-hung rudders, very light displacement of 2.25T. No inboard engine but an outboard (yes, I am happy with that, it's a sail boat), no portholes, no thru-hulls. I have a very good NA for the hull design, so no issues there.

The sailing will be single of short handed crew, max crew of four, from Sydney out into the wide open ocean: Tasmania, New Zealand, the Pacific, Asia. Yes, we will have to pick our weather, but we also bring storm sails and a JSD.

It is the rig/mast/sail plan that I have questions about. I want the fastest and easiest rig possible for this light hull. I am open for anything and everything, so I need some help to focus and make up my mind, please.

I was thinking of a carbon mast, preferably rotating/wing profile if possible(?), no backstay or running, textile shrouds/stays where possible, with a square top main (see Pogo 30), but with cutter foresails for ease of handling and trimming (and they look cool), we will have a sprit, and code sails for down wind courses.

Is this possible or am I dreaming? Should I look at some other type of rig/sail plan?

You will need running stays for the mast top code sails at least and I think you need a back stay (of some kind) opposing every fore stay. There are far greater authorities here than me but to minimize rig weight up high that is what I would do.

A large profile wing mast might allow you to fudge this rule if the cutter stays are not far apart.

My approach would be to start by mapping the sail plan on a wind speed vs wind angle graph. Does the Cutter make sense? High performance dictates that you only take what you need.

 

[Stumble]

It is certainly possible, but you may have to add a lot of carbon to the mast to resist the cutter rig. I am not sure it would be worth it.

Cutters by their nature move the mast back and end up with small mains and large headsails. Modern rig designs push the mast forward, use a large main and small non-overlapping headsail with large sprints for power off the wind. So to the extent I think you have competing goals.

If you want a cutter rig, then get one, boats are not logical after all. But if you want performance shove that rig forward use a small headsail, and big main.

Backstays and runners are not needed, just take a look at the Pogo's, and most multihulls. You just need to pull the shrouds back.

 

[Doug Lord]

Cutter rig

Most really big tri's have the rig way back-like a cutter- to help prevent pitchpole. So its definitely possible but may not be as quick on a mono:

 

[gggGuest]

In so far as anything is transferrable in ideas from the big multis, which is debatable, its probably more realistic to think of them as being basically much smaller and shorter boats that have greatly extended bows.

 

[Skyak]

It is certainly possible, but you may have to add a lot of carbon to the mast to resist the cutter rig. I am not sure it would be worth it.

Cutters by their nature move the mast back and end up with small mains and large headsails. Modern rig designs push the mast forward, use a large main and small non-overlapping headsail with large sprints for power off the wind. So to the extent I think you have competing goals.

If you want a cutter rig, then get one, boats are not logical after all. But if you want performance shove that rig forward use a small headsail, and big main.

Backstays and runners are not needed, just take a look at the Pogo's, and most multihulls. You just need to pull the shrouds back.

The big swept back spreaders to the edge of the boat (still called a B&G rig?) limit the overlap/sheeting of upwind sails which might help explain why you don't see many as cutters.

Multihulls are too different to offer useful reference unless you go with the big spreaders at the base like IMOCA -even then the heel and drag are too different.

The intended waters are very demanding so there is likely a big difference between 'can' and 'should'.

 

[Beacon Hill Ben]

From my on-screen measurements: the Pogo 30 has it's mast at 47% from the bow, so not far from the middle. I'll ask my NA to have a look at the P30 and see if that would work for our hull.

I also had a look at the Sydney-Hobart contenders (which are designed for my local waters), from this helpful picture:

Comanche: Mast at 50.7% from bow: behind the mid-point!
Wild Oats XI/2014 (before bow extension?): mast at 43%
Perpetual Loyal: 48%
Ragamuffin 100: 44%
RIO 100: 42%

 

[Stumble]

Beacon,

Other than the Pogo every one of the boats you posted uses at least running backs, and I am pretty sure all of them also use check stays and other ways to control the rig. The same for the Tri Doug posted.

If you want to move to a highly complicated rig with runners, checks and intermediate checks that's an option, but it is not a simple, rig.

Rio for instance has runners, and three sets of checks. Obviously a reasonable rig on a maxi racer, but a bit much if you want a simple, no runners, design.

 

[Stumble]

The big swept back spreaders to the edge of the boat (still called a B&G rig?) limit the overlap/sheeting of upwind sails which might help explain why you don't see many as cutters.

Multihulls are too different to offer useful reference unless you go with the big spreaders at the base like IMOCA -even then the heel and drag are too different.

The intended waters are very demanding so there is likely a big difference between 'can' and 'should'.

It wouldn't be a B&R rig because the goal isn't to reduce mast section by using lots of intermediate stays. My recomendation would be a Pogo style rig, with caps, one set of intermediates, and a heavy wall big stick. This way you can get rid of the backstay, still use a mast head code zero, and have a simple rig to tune.

 

[Beacon Hill Ben]

...My recomendation would be a Pogo style rig, with caps, one set of intermediates, and a heavy wall big stick. This way you can get rid of the backstay, still use a mast head code zero, and have a simple rig to tune.

Thank you Greg.

 

[CT249]

If you're looking at a light boat without vast beam, then why a wing mast? For a boat like that, the reduced weight and improved gust response of a standard section is normally faster. Wings have been tried in similar boats since the '80s and repeatedly abandoned. As I understand it, for a given weight and heeling moment, one is better off using a taller mast than a wing mast in boats of this type. In multis, where less mast bend is used for gust response, it's a different thing.

You may also find that the mast-aft design is used in very stable boats with big rigs, where very high speeds make nosediving more of an issue. Even the Pogo is a bigger and beamier boat than yours (which seems to be a much more balanced design, IMHO).

I've done a bit of bouncing around off NSW, Bass Strait and Tassy in boats of very similar general dimensions to yours. I'd go straight for a standard mast with short overlap sloop rig. It's incredible versatile and incredibly simple. My old boat has gone from masthead rig to IOR-type fractional rig (runners, 150% overlap headsail, narrow in-line spreaders) and now to a short overlap swept-spreader rig. I find the current rig to be amazingly fun and easy to use. Just by sheeting the headsail further out and extra tweaking we can handle a very wide wind range. I don't think I'd own a different rig on an offshore mono.

 

[CT249]

In so far as anything is transferrable in ideas from the big multis, which is debatable, its probably more realistic to think of them as being basically much smaller and shorter boats that have greatly extended bows.

Yep, that's pretty much what exactly what Nigel Irens said about them, from memory. Catsketcher (who has interviewed Nigel and been about some of the big tris) could confirm it.

 

[Beacon Hill Ben]

If you're looking at a light boat without vast beam, then why a wing mast? For a boat like that, the reduced weight and improved gust response of a standard section is normally faster. Wings have been tried in similar boats since the '80s and repeatedly abandoned. As I understand it, for a given weight and heeling moment, one is better off using a taller mast than a wing mast in boats of this type. In multis, where less mast bend is used for gust response, it's a different thing.

You may also find that the mast-aft design is used in very stable boats with big rigs, where very high speeds make nosediving more of an issue. Even the Pogo is a bigger and beamier boat than yours (which seems to be a much more balanced design, IMHO).

I've done a bit of bouncing around off NSW, Bass Strait and Tassy in boats of very similar general dimensions to yours. I'd go straight for a standard mast with short overlap sloop rig. It's incredible versatile and incredibly simple. My old boat has gone from masthead rig to IOR-type fractional rig (runners, 150% overlap headsail, narrow in-line spreaders) and now to a short overlap swept-spreader rig. I find the current rig to be amazingly fun and easy to use. Just by sheeting the headsail further out and extra tweaking we can handle a very wide wind range. I don't think I'd own a different rig on an offshore mono.

Thanks CT, your experience is appreciated. Any chance I could come have a look at your boat, seeing you're in Sydney? PM me if that is OK, thanks.

 

[CT249]

Ben;

My old rotrocket is down at Batemans Bay (I should update my sig) and (unlike others 30s I've sailed, such as half tonners, Hicks and Youngs) although light she's significantly smaller and much older than your boat so wouldn't be of much use for inspiration; she's a 28'er that's about J/24/Holland 30/S 80 pace so will be sailing very different angles and at lower speed than your boat. She also uses an old Etchells main and mast so she's not the same as the modern rigs in terms of proportions, design and materials.

I mentioned her because it's been interesting to use the three different rigs on the same boat. I was also lucky enough to sail a Mumm 36 that lost her old one design rig (in-line spreaders, runners and 150% overlap) and had it replaced by a short-overlap rig. That partly inspired me to swap my rig over since the short overlap swept spreader rig was so nice to use. Years ago I'd used an even smaller jib when sailing the "works team" Noelex 30 which had a self tacker, but as dinghy and skiff experience seems to indicate, having a short overlap seems to add a worthwhile extra bit of power.

The Pogo rig looks pretty nice; I wonder if the forestay isn't a bit high for a narrower boat like yours. Personally the Pogo looks to be like one of those boats that's so beamy and deep and carries so much sail it's not really a 30 footer but a 35 footer with the cheap bit at the back cut off; IMHO your narrower and lighter boat seems to have much nicer proportions.

 

[Kapteeni Kalma]

The Comanche drawing is nice, but not accurate. Comanche has huge aftermast position at 55-56% from the bow. About the same as the VPLP Imoca's.
Perpetual Loyal is right at 48%.
There is some merit to the aftmast design. The mast lands right to the hull's longitudional pivot point. So in chop the mast and chainplate structure does not hop up and down as much. This saves energy, and Comanche does markedly less piss upwash in the bow.