What boatspeed should I expect, as a percentage of True wind?

[fxykty]

Originally Posted by JustMurph

I don’t know that I entirely agree with that, but I might just get a chance to test it tomorrow with what looks like it will be a light DDW run home in the arvo.



My understanding is that on fast cats like these, you are better off running angles in lighter winds and DDW as the wind speeds come up. In my above example with the Code D, I think my mistake was that the wind was light enough that I should have been running the spinnaker, in which case I could have run a lot deeper, with a far better VMG. I chose to stick with the code D as it was just me and one very green friend.....and we had lots of time.

Well, an L40 is not a light boat, so the DDW with a spinnaker is entirely appropriate for most wind strengths. Even for a performance cat DDW is often easier than gybing back and forth, especially when there’s a bit of wind. Heck, in 20+ knots heading DDW our boat is 60% wind speed with just our self tacking jib barber hauled out to the rail (waves to surf on really help increase the average speed). Sure we could go faster gybing at 140 TWA but I’m not sure the VMG would be much better and it would be a lot more work.

In lighter winds however, for our boat, using the gennaker and dragging the wind to 80-90 AWA yields a boat speed between 75-90% of TWS and 140-150 TWA (VMG of 60-75% TWS). DDW would be a lot slower in lighter air.

[JustMurph]

Originally Posted by fxykty

Well, an L40 is not a light boat, so the DDW with a spinnaker is entirely appropriate for most wind strengths. Even for a performance cat DDW is often easier than gybing back and forth, especially when there’s a bit of wind. Heck, in 20+ knots heading DDW our boat is 60% wind speed with just our self tacking jib barber hauled out to the rail (waves to surf on really help increase the average speed). Sure we could go faster gybing at 140 TWA but I’m not sure the VMG would be much better and it would be a lot more work.

In lighter winds however, for our boat, using the gennaker and dragging the wind to 80-90 AWA yields a boat speed between 75-90% of TWS and 140-150 TWA (VMG of 60-75% TWS). DDW would be a lot slower in lighter air.

I'll clarify that I'm talking about lighter performance cruising cats. Like you, in a bit more air I'll just go DDW wing on wing and do around 50% of wind speed (60 is hooking along!). I'm specifically talking about light wind where running angles is faster, but obviously more work.

[Chotu]

I’m never going to jybe downwind and do a lot of my sailing downwind because I’m lazy and enjoy a comfortable ride. I’ll wait a day for the weather to change so I can have an easy ride, not bashing into seas.

I’d also probably go out in light air a lot more often once this boat is ready. So I suppose my only upwind sailing will be in light airs, so the sea state is comfortable.

I’m usually reaching or running.

What sail should I start with aside from main and jib?

I have the same boat as Grit, other than our individual modifications.

[barnakiel]

Originally Posted by JustMurph

I don’t know that I entirely agree with that, but I might just get a chance to test it tomorrow with what looks like it will be a light DDW run home in the arvo.

My understanding is that on fast cats like these, you are better off running angles in lighter winds and DDW as the wind speeds come up. In my above example with the Code D, I think my mistake was that the wind was light enough that I should have been running the spinnaker, in which case I could have run a lot deeper, with a far better VMG. I chose to stick with the code D as it was just me and one very green friend.....and we had lots of time.

As others explained. Lagoons are heavy boats.


It takes quite a lot of extra speed to justify the extra way. Another factor is that in an ocean crossing ddw may coincide with waves square on the stern which tends to give the most comfortable ride as judged by very many cat crews. Plus - no gybing.


So. Ddw under a symmetrical kite is fast, comfortable and hassle free.



b.

[JustMurph]

I missed the bit where this because a conversation about Lagoons.

[fxykty]

Originally Posted by Chotu

I’m never going to jybe downwind and do a lot of my sailing downwind because I’m lazy and enjoy a comfortable ride. I’ll wait a day for the weather to change so I can have an easy ride, not bashing into seas.

I’d also probably go out in light air a lot more often once this boat is ready. So I suppose my only upwind sailing will be in light airs, so the sea state is comfortable.

I’m usually reaching or running.

What sail should I start with aside from main and jib?

I have the same boat as Grit, other than our individual modifications.

First would be a 300-400% gennaker or code 0 for reaching. It should be cut to work from 60-70 AWA (or even 45-50 AWA, if not planning a screecher) down to 130 AWA, and deeper if flown alone or tacked to the windward bow.

Is your jib 95-100% (self-tacking) or overlapping 120-130%? If the former, a light air screecher cut for close hauled would be useful as a second flying sail.

Finally, for lighter air deep reaching or DDW, a symmetric or asymmetric spinnaker. The latter on a top down furler may be simpler to use than a socked symmetric, while the latter may fly better DDW. I’ve heard mixed reviews about the wingaker type spinnakers for multihulls and their cost is certainly much more, but you could consider one of those. They do apparently stay much more stable, especially if there is slop around.

Regarding sailing upwind, what’s the problem? You have fine hulls and reasonable length and bridgedeck layout, which mitigate all the issues that fatter and heavier cats have when going upwind. But if you do truly only want to reach and run, don’t bother buying anything but cross cut Dacron sails - save the money for provisions.

[Chotu]

Originally Posted by fxykty

First would be a 300-400% gennaker or code 0 for reaching. It should be cut to work from 60-70 AWA (or even 45-50 AWA, if not planning a screecher) down to 130 AWA, and deeper if flown alone or tacked to the windward bow.

Is your jib 95-100% (self-tacking) or overlapping 120-130%? If the former, a light air screecher cut for close hauled would be useful as a second flying sail.

Finally, for lighter air deep reaching or DDW, a symmetric or asymmetric spinnaker. The latter on a top down furler may be simpler to use than a socked symmetric, while the latter may fly better DDW. I’ve heard mixed reviews about the wingaker type spinnakers for multihulls and their cost is certainly much more, but you could consider one of those. They do apparently stay much more stable, especially if there is slop around.

Regarding sailing upwind, what’s the problem? You have fine hulls and reasonable length and bridgedeck layout, which mitigate all the issues that fatter and heavier cats have when going upwind. But if you do truly only want to reach and run, don’t bother buying anything but cross cut Dacron sails - save the money for provisions.

Thanks for this awesome post. I love learning about all these new options available with this type of Catamaran. Never had anything like this before. And I’m coming from monohull and very slow Catamaran history. Just from motoring this boat, I do understand what you mean about the fine entry. A Sportfisher, 80 feet long, can be going by at the worst possible semi displacement speed, that wave hits me, I don’t feel a thing and the bridge deck doesn’t touch. I suppose that motion is the same type of motion that will keep the boat tracking smoothly going to weather. Maybe I have to think about this differently.

[JustMurph]

Chotu: Have a play sailing to windward, I'm pretty confident you'll be pleasantly surprised. I've certainly been very happy with how well my boat does it and I'd expect yours will be better again.

I had a nice sail home this afternoon under main and spinnaker in anything from 8 - 16 knots true. I didn't end up collecting all the data I wanted to (too good an afternoon to not just kick back and enjoy it), but a few quick calcs say we had better VMG gybing downwind in the lighter winds, but by the time the wind pick up to 16 and we were doing 10.5 knots, the VMG would have been about the same. I'd need to test more running just the spin DDW.

[Dave_S]

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[Dave_S]

Originally Posted by JustMurph

Chotu: Have a play sailing to windward, I'm pretty confident you'll be pleasantly surprised. I've certainly been very happy with how well my boat does it and I'd expect yours will be better again.

I had a nice sail home this afternoon under main and spinnaker in anything from 8 - 16 knots true. I didn't end up collecting all the data I wanted to (too good an afternoon to not just kick back and enjoy it), but a few quick calcs say we had better VMG gybing downwind in the lighter winds, but by the time the wind pick up to 16 and we were doing 10.5 knots, the VMG would have been about the same. I'd need to test more running just the spin DDW.

Doing 10.5kn DDW in 16kn true you would need to sail at 85% of wind speed at 140° true to equal VMG.

[JustMurph]

Originally Posted by Dave_S

Doing 10.5kn DDW in 16kn true you would need to sail at 85% of wind speed at 140° true to equal VMG.

We were running angles, not sailing DDW.

[GRIT]

We've got a bit of use out of the Code zero for the last month, and it's improved our numbers somewhat.

With the true wind at around 110 degrees, with code zero and full main, we can do between 80% and 100% of windspeed, up to around 9 knots. Any more wind than 10 knots, and 100 T seems to be our limit, as the apparent wind gets to around 50 degrees, and the code 0 starts to luff.

With the wind around 140 degrees, we've been seeing between 60 and 75% of windspeed. Though today with the sail weighted with dew, we are lucky to hit 5 knots in 8 knots at 130 true. The sun's up now, and it'll dry soon, then we hope to see better numbers.

Crossing the gulf stream, on our way back to the USA from the Bahamas, we saw a steady 13 knots in a shifty 17 knots of wind at 110 T, and 55 apparent and waves just on the beam. I furled it up at that point, as my wife was sleeping, and the waterfall noise from the wakes was getting loud. With the 100% jib, the speed dropped to 9 knots, which seems to be a sweet spot for this boat. No wake noise, and the ride is always placid at 9 knots.

We're planning our next sail purchase, for this fall. It'll be a spinnaker, but I don't know if it'll be a Sym or Asym. Whatever it is, it'll be the biggest we can get to fit, for light airs. The code 0 seems like it should be bigger than it is. It barely gets by the shrouds, and I'd thought it would get nearer the running back chainplate. It's 1000 ft2, which I thought was big, until we flew it.

That's my report, for now. We're still learning to sail her; but we're having fun at it.

Paul.

[smj]

Originally Posted by GRIT

We've got a bit of use out of the Code zero for the last month, and it's improved our numbers somewhat.

With the true wind at around 110 degrees, with code zero and full main, we can do between 80% and 100% of windspeed, up to around 9 knots. Any more wind than 10 knots, and 100 T seems to be our limit, as the apparent wind gets to around 50 degrees, and the code 0 starts to luff.

With the wind around 140 degrees, we've been seeing between 60 and 75% of windspeed. Though today with the sail weighted with dew, we are lucky to hit 5 knots in 8 knots at 130 true. The sun's up now, and it'll dry soon, then we hope to see better numbers.

Crossing the gulf stream, on our way back to the USA from the Bahamas, we saw a steady 13 knots in a shifty 17 knots of wind at 110 T, and 55 apparent and waves just on the beam. I furled it up at that point, as my wife was sleeping, and the waterfall noise from the wakes was getting loud. With the 100% jib, the speed dropped to 9 knots, which seems to be a sweet spot for this boat. No wake noise, and the ride is always placid at 9 knots.

We're planning our next sail purchase, for this fall. It'll be a spinnaker, but I don't know if it'll be a Sym or Asym. Whatever it is, it'll be the biggest we can get to fit, for light airs. The code 0 seems like it should be bigger than it is. It barely gets by the shrouds, and I'd thought it would get nearer the running back chainplate. It's 1000 ft2, which I thought was big, until we flew it.

That's my report, for now. We're still learning to sail her; but we're having fun at it.

Paul.

A steady 13 in 17 knots of wind, I’m guessing it took awhile to wipe that grin of your face! [emoji23]

[GRIT]

YES, and it took all I could all the gentlemanly power I could muster to take it down so my wife wouldn't wake up due to the noise.

Cheers.
Paul.

[Tupaia]

Originally Posted by GRIT

We've got a bit of use out of the Code zero for the last month, and it's improved our numbers somewhat.

With the true wind at around 110 degrees, with code zero and full main, we can do between 80% and 100% of windspeed, up to around 9 knots. Any more wind than 10 knots, and 100 T seems to be our limit, as the apparent wind gets to around 50 degrees, and the code 0 starts to luff.

Paul.

Nice numbers.

Where is your code zero sheeted ? You should be able to go closer than 50˚ apparent especially in very very light winds. If your sheeting angle is too wide you could use a barber hauler to pull the sheet more towards the centre of the boat. Also the luff has to be really tight.