Aftmast rigs???

[gggGuest]

Are most races mostly upwind and down wind, distance wise?

There's a very recent fashion for upwind and downwind only races. That happened long after bermudan rigs were accepted. There are signs that fashion may pass. But long distance racing has always been passage racing.

In any form of competitive sailing upwind performance is dominant because a 1% increment on travelling upwind at 3 knots is more beneficial than a 1% increment on going downwind at 5 knots if you end up where you started from.

Of course upwind performance is also vital for a fisherman trying to get off a lee shore before he and his boat are dashed to pieces on the rocks. You just have to look at rigs over the centuries to see that design improvements are dominated by the desire for more upwind speed.

 

[OzFred]

There's a very recent fashion for upwind and downwind only races. That happened long after bermudan rigs were accepted. There are signs that fashion may pass.

It is my understanding that windward/leeward courses are a consequence of boats that have their best downwind VMG when not going dead down wind. In such boats it becomes tactical to gybe downwind and pick lifts, headers and gusts just like upwind.

It also allows them to sail in stronger breeze without having to shorten sail (which most racing skiffs and dinghies can't or aren't allowed to do on the water), in gusts they just point lower without having to worry about falling too far below the wing mark lay line.

 

[brian eiland]

Maxi Boat 'Comanche' & its aft placed mast

Interesting to note that Comanche, which just won line honours in the 2015 Rolex Sydney Hobart Yacht Race, is an aft mast rig. Unfortunately Wild Oats XI had to retire, but was being led by Comanche at the time. Some details of Comanche's rigging were reported in Scuttlebutt Sailing News in Oct 2014 http://www.sailingscuttlebutt.com/2014/10/22/building-trust-comanche/

Thanks for that posting. I was not aware of that vessel. I'm going to have to do a little research and asking some questions as to how they arrived at some of their decisions in the design process.

It seems obvious that they thought a great deal about the advantages of headsails considering that large fore-triangle.

Our boat and sail designers used sophisticated modeling capabilities, early in the conceptual phase, to help determine where to place the mast. The team worked closely with naval architects at Verdier Yacht Design, VPLP and JB Braun of North Sails Design Services as they were deciding where to place the mast and appendages. And at the end of the day the mast kept sneaking back…model, test, conclude, try again. We interpreted the position you see today as the most efficient for all-around sailing, especially considering the hull and foil configuration.

I at first didn’t believe having our mast well beyond 50% aft of the bow was efficient, but JB showed us the models and the computers proved us wrong. When it comes to these decisions, you have to trust the experts and their data. That’s what these smart guys get paid for, right?
- See more at: http://www.sailingscuttlebutt.com/2014/10/22/building-trust-comanche/#sthash.RQg2EizY.dpuf

 

[brian eiland]

Rating Rules & Boat Design

CT. Is it possible that the Bermudan rig is best for going up wind, which seems to be the most important point in racing?

I read in a post somewhere that much of racing now days is up wind and down wind, without much reaching.

Since I have never participated in an organized race in my life, I am quite ignorant on this matter.

It appears that the greatest gift of the Bermudan rig is its high aspect ratio, base on the formula: (Span^2)/Area.

In a race that is mostly upwind and down wind, a rig, such as this, could have a double advantage:

1.) upwind, its higher AR allows it to sail closer to the wind, and
2.) its taller mast (to get sufficient SA) allows for flying a bigger spinnaker.

I wonder if this is what some postors are referring as "the rules".

Not so much "design rules" but "race condition rules".

Are most races mostly upwind and down wind, distance wise?

I thought this was an interesting quote.

Comanche was designed and built with two goals in mind for any sailing she will do:
first, always try to take line honors and second, break a record when the weather cooperates. In fact, the design office, Verdier and VPLP, were told specifically by me that if this boat isn’t the worst rated boat in history (IRC or ORR) they have failed.

Goal one, first to finish, comes down to the team onboard and hopefully the speed of the boat, something that is in our control.

Goal two is weather dependent but that’s how sailing goes. - See more at: http://www.sailingscuttlebutt.com/2014/10/06/last-comanche-nears-liftoff/#sthash.lTW1cZP5.dpuf

 

[brian eiland]

Tour of Comanche
https://www.youtube.com/watch?v=oDcWkjjr8_0

I was disappointed there was no discussion of the aft placed mast rig, particular by the sail maker Ken Read.

Then I discovered at least a mention of the aft rig design run-up here:
https://www.youtube.com/watch?v=zZARRrHWlqs

 

[DennisRB]

I don't think these super maxi racing yachts have a "aft mast" rig in the same way Brian describes them. Look at Wild Oats. They went to the trouble of moving the mast and keel back so they would have more bow. Well the actual way they did it was to cut the stern off then make a whole new bow. The reason they did this (its in all the articles), and I assume Comanche was already built like this, is so they can carry massive sail areas downwind with out nose diving when ocean racing.

They have what is a usual boat and rig but with a lot of extra buoyancy forward. The same thing with many racing multihulls. Its all to keep the bows up. Now when you have a long bow sticking out forward on a racing boat of course you are going to run your lighter sails all the way to the front. Look at the amount of inner foresails they carry!

Wild Oats still wouldn't be mast aft even after the mods, but they obviously thought moving the mast and keel back was worth this multi million dollar modification.

....I still would never want a main bigger than on my boat (43 foot performance cruising cat) which is 70m2. Its hard to raise as its. I think 55m2 would be a more manageable size to raise. Once its up, its fine. But the sheer size is a little daunting downwind in strong wind, and roached mainsails on cats are always a PITA downwind on cats thanks to shrouds.

I think a more aft mounted mast would still be great even for a performance cat like mine. The mast would be the same height. The main would have a shorter boom and then have an aggressive squaretop. Over all it would probably loose about 30% area (so become 50m2) but be higher aspect (with rotating mast) so it should still have great windward performance in combination with a larger headsail which would also be 55m2 up from 40. This would probably move all the effort from raising the main to sheeting in huge headsails though. Deck gear would need to made very strong and maybe even electric sheet winches. There would be at least 2 permanent head sails and the screecher/spin would be removable on a pole.

I have been single handing lately and just using the 40m2 headsail. For shorter trips its probably not much slower than using the main too when you include raising and lowering it then packing everything away. Having larger headsails are obviously a benefit here. The main issue I see is it seems hard to put the mast in a nice spot so you still have a decent sized main. Its either before the cabin on the main bulkhead, or waaaay back on the back of the cabin top, which seems to far back for what I would like. Not that I am ever going to change anything on my boat, but one day when I finally build one...

 

[sharpii2]

I don't think these super maxi racing yachts have a "aft mast" rig in the same way Brian describes them. Look at Wild Oats. They went to the trouble of moving the mast and keel back so they would have more bow. Well the actual way they did it was to cut the stern off then make a whole new bow. The reason they did this (its in all the articles), and I assume Comanche was already built like this, is so they can carry massive sail areas downwind with out nose diving when ocean racing.

They have what is a usual boat and rig but with a lot of extra buoyancy forward. The same thing with many racing multihulls. Its all to keep the bows up. Now when you have a long bow sticking out forward on a racing boat of course you are going to run your lighter sails all the way to the front. Look at the amount of inner foresails they carry!

Wild Oats still wouldn't be mast aft even after the mods, but they obviously thought moving the mast and keel back was worth this multi million dollar modification.

....I still would never want a main bigger than on my boat (43 foot performance cruising cat) which is 70m2. Its hard to raise as its. I think 55m2 would be a more manageable size to raise. Once its up, its fine. But the sheer size is a little daunting downwind in strong wind, and roached mainsails on cats are always a PITA downwind on cats thanks to shrouds.

I think a more aft mounted mast would still be great even for a performance cat like mine. The mast would be the same height. The main would have a shorter boom and then have an aggressive squaretop. Over all it would probably loose about 30% area (so become 50m2) but be higher aspect (with rotating mast) so it should still have great windward performance in combination with a larger headsail which would also be 55m2 up from 40. This would probably move all the effort from raising the main to sheeting in huge headsails though. Deck gear would need to made very strong and maybe even electric sheet winches. There would be at least 2 permanent head sails and the screecher/spin would be removable on a pole.

I have been single handing lately and just using the 40m2 headsail. For shorter trips its probably not much slower than using the main too when you include raising and lowering it then packing everything away. Having larger headsails are obviously a benefit here. The main issue I see is it seems hard to put the mast in a nice spot so you still have a decent sized main. Its either before the cabin on the main bulkhead, or waaaay back on the back of the cabin top, which seems to far back for what I would like. Not that I am ever going to change anything on my boat, but one day when I finally build one...

I don't think you can have an "aggressive square" top main if you want your head sails to stand adequately.

In order to get sufficient luff tension, you need your back shrouds to run from the very top of your mast to the very ends of your hulls. Depending on mast height and maximum Beam, this could leave as little as 90 degrees total for the top of this main to swing. Maybe 45 degrees or less per tack.

It's probably better to tolerate an additional loss of SA than to have to deal with a main almost always chafing on its back shrouds.

 

[DennisRB]

I see your point that the angle would be even worse than now, but it does not have to be much worse. But the main would not be needed downwind or as often. That's the whole point. Even with the shroud angles I have now the main sucks deep downwind. The best solution is just not to use the main at all (speed from 12K to 8). In lighter winds the craft I have in mind will be fast enough that the wind would rarely come from further aft than the beam anyway. When the wind is strong enough that it is coming from aft there will be no need to have the main up at all. My current boat is pretty close to this already. A fantasy build would of course be even faster.

 

[CT249]

CT. Is it possible that the Bermudan rig is best for going up wind, which seems to be the most important point in racing?

I read in a post somewhere that much of racing now days is up wind and down wind, without much reaching.

I wonder if this is what some postors are referring as "the rules".

Not so much "design rules" but "race condition rules".

Are most races mostly upwind and down wind, distance wise?

It's not something I've specifically researched, but if I recall correctly the very first yacht race ever recorded had one upwind and one downwind leg. That was dictated by the geography of the Thames, but we can also note that the initial challenge that sparked the America's Cup required that the course "test the qualities before and by the wind". The two matche races that America sailed (against Titania and Sverige) were windward/leewards, so they are an ancient part of sailing.

You can also find many old comments about the fact that windward ability was the prime test of a boat. I can recall incidents where the old "wooden walls" of the Napoleonic Wars and similar ships, for example, placed enormous importance on upwind ability for station keeping, catching the enemy (or running away) and staying off lee shores. Obviously, keeping off a lee shore is vital - so was being able to get into or out of a harbour before engines. It's therefore apparent that from a very, very early stage it was accepted that windward ability should be tested thoroughly.

Since the extreme importance placed on windward ability dates back to before the 1860s, well before really modern races, it seems that putting a high value on upwind performance is almost an innate part of sailing. The idea that windward ability is unimportant may only have applied in certain (common) situations, including short-range fishing vessels (I'd expect that if your fishing grounds were directly upwind or downwind you'd just find a different harbour so you could reach to and fro), oceanic passages, and cruising yachts.

As far as racing courses go, as noted by others ocean racing is often downwind or reaching - you crack sheets and foot and then wait until the wind shifts so you can get back on course. Many, many major distance races have been won by boats that were not the fastest in their class upwind. A quick check from memory shows that when I was ocean racing the most, half or more Hobarts were won by boats that were not the fastest upwind boats in their class. So ocean racing doesn't place a particularly high value on windward performance. Maybe modern cruising just places an unusually LOW value on windward performance?

 

[DennisRB]

"Maybe modern cruising just places an unusually LOW value on windward performance?"

Its not against the rules to start your engine. Its not a race so it doesn't matter if you wait until favorable winds.

That said, I am a cruiser and windward performance matters to me. But for hulls that don't go to windward (charter cats), it makes sense to not use rigs optimized for windward performance if that same rig has performance disadvantages for reaching or downwind sailing angles. Something along the lines of what Brian promotes makes sense here IMO.

 

[brian eiland]

It is my understanding that windward/leeward courses are a consequence of boats that have their best downwind VMG when not going dead down wind. In such boats it becomes tactical to gybe downwind and pick lifts, headers and gusts just like upwind.

While this may be true for very performance oriented boats, most cruising boats never really attain these kind of apparent wind conditions that make tacking downwind a viable alternative.

 

[brian eiland]

Rig assessment article from wayback machine...
http://cruisenews.net/images/FastestRig1.jpg

The final paragraph there;
"The results came as a surprise, and overturn the comman assumption about the bermudian rig. The best rig, on all points of sailing, was the sprit sail. Its superiority was especially marked when sailing to windward."

I wonder what Marchaj had to say about that? ,....I can't remember

Someone was questioning the real world examples of the Delta rig. There are two more pages.
The purpose of the "mastaft rig" is to establish space for clean luffs and lifting sail(s), not simply to put the mast aft. If you put the mast aft and don't use the space to change the sail rig from the standard conventional Marconi, I am not sure what the point is.

Can you post those other 2 pages, or a link to them?

 

[OzFred]

While this may be true for very performance oriented boats, most cruising boats never really attain these kind of apparent wind conditions that make tacking downwind a viable alternative.

Yes of course, asymmetric spinnakers are at a serious disadvantage where they are constrained to angles outside their narrow performance lane, say by marks or channels or the rhumb line to the next anchorage.

I was just commenting on why windward/leeward courses have become popular for racing. Boats with symmetric spinnakers or no spinnaker will no doubt continue with at least one lap around one or more wing marks.

 

[brian eiland]

Somewhat similar...ha...ha

 

[brian eiland]

Somehow I forgot how to post that image above to a comparable size to the Comanche photo??

...few other images to compare with