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Dave_S

Help to improve cruising catamaran to windward

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I have a Schionning Waterline 1480 and it sails quite well tacking upwind but I hate giving anything away.  I don't think there is anything wrong, I just wondered if there are some design aspects that can be changed/improved that might help me squeeze a few more degrees from it.  

What makes a better upwind boat for CMG. 

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vmg is more important than hight, what are the wind angles tru and apparent on the wind you sail?

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If you are thinking "a few more degrees" you are thinking in the wrong direction. I am no catamaran expert, but I have done a few mixed cat/mono races on the beasts and also raced against them with my SC 50. The cats do quite well heading wayyy low. Like they are on a different course. Going fast. It seems hopeless but at the top mark the tactic proves itself. So like mowgli says above, it is not the degrees, it is the VMG.

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Better boards, better sails, less headstay sag, better mainsheet system, less weight. That's the short list. More lift/less drag, both above and below the waterline  

 

Doesn't matter if it's a mono or cat or tri, upwind height counts! I'd take 12 knots at 47 TWA any day over 12 knots at 55 TWA. 

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Agree with Soma.Asked Reni Gelder when he won the Trans Tasman what his secret was      hanked on headsail    plus twin headsails      he had spent a long time changing the angle of the centreboard    almost no added weight     AIS so he could sleep safely   . His partner said if Reni could get dehydrated water he would,she was amazed when I said we had it in Aust then peeved when I said you just add water to reconstitute it.   Oh and apparently he sailed from 5 years old in Austria. Austria with inland lakes, high mountain peaks with treacherous winds prepares one very well for ocean racing. Cheers Bottman PS headsail furler is not conducive to fast sailing.

 

 

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Agreed,  the higher I can point with good flow over the sails seems to be best VMG.  I have heard that coming down a few degrees helps but it doesn't seem to in practice.  

I was thinking along the lines of changing the shape and/or the angle of attack of the boards to favour one tack,  similar lift for each tack by only using the windward board and less drag.

Has this been done, Would it be hard to manage accelerating up and down waves ?

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4 hours ago, daddle said:

If you are thinking "a few more degrees" you are thinking in the wrong direction. I am no catamaran expert, but I have done a few mixed cat/mono races on the beasts and also raced against them with my SC 50. The cats do quite well heading wayyy low. Like they are on a different course. Going fast. It seems hopeless but at the top mark the tactic proves itself. So like mowgli says above, it is not the degrees, it is the VMG.

Is it less tactics and more necessity, I hit a wall, with the sails pulled in as close to centreline (7° for the jib and the boom is slightly to windward) I can sit on the edge with a hint of windward telltail flutter and make best CMG, but as soon as I get a little greedy it falls in a hole, almost completely stalls. 

If I vere off a little I can pickup a more speed but CMG goes down. I know very little of other boats so it could easily be tactics but that angle they are on might just be the best they can do without falling in the hole.

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what speed will she do upwind?

As soma said.

Schionning foils are often "average" so need plenty of speed to get them working well.

Very easy to choke a multi

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4 hours ago, soma said:

Better boards, better sails, less headstay sag, better mainsheet system, less weight. That's the short list. More lift/less drag, both above and below the waterline  

 

Doesn't matter if it's a mono or cat or tri, upwind height counts! I'd take 12 knots at 47 TWA any day over 12 knots at 55 TWA. 

Better mainsheet system has picked up my interest, not sure what you mean. I do wonder how to keep the flow attached if I manage to point higher. 

 

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4 minutes ago, eastern motors said:

Barber haulers?

I don't have them at the moment, I have been thinking of doing that as it will be easy to set up. My inner jib rails are 7° of centreline and in some conditions I do see some choking on the front of the main but at other times I could squeeze a bit more. 

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10 minutes ago, bushsailor said:

what speed will she do upwind?

As soma said.

Schionning foils are often "average" so need plenty of speed to get them working well.

Very easy to choke a multi

Best to date,  In 12kn AWS we made 8.5 kn at 30° AW both boards fully down. 

I would like to work on some new boards,  I think there are some benefits to be had. Is there some information out there on good designs. 

It does choke sometimes, I get a bit of crush on the front of the main but it doesn't seem to slow down, I guess a little is OK? 

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6 hours ago, Dave_S said:

Is it less tactics and more necessity, I hit a wall, with the sails pulled in as close to centreline (7° for the jib and the boom is slightly to windward) I can sit on the edge with a hint of windward telltail flutter and make best CMG, but as soon as I get a little greedy it falls in a hole, almost completely stalls.  

If I vere off a little I can pickup a more speed but CMG goes down. I know very little of other boats so it could easily be tactics but that angle they are on might just be the best they can do without falling in the hole.

That sounds like you're pinching - the worst thing to do on a cat.

Let it all out and go fast so the speed works on the surfaces then you'll find you're pointing higher.

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50 minutes ago, knobblyoldjimbo said:

That sounds like you're pinching - the worst thing to do on a cat.

Let it all out and go fast so the speed works on the surfaces then you'll find you're pointing higher.

I've heard this before and maybe I'm not describing it well or just misunderstanding and should listen more. I describe pinching as the angle upwind at the point or beyond where I am starting to fall in the hole,  beyond which speed rapidly falls off and you can feel you have fallen out of the groove and lost all the power. I can sail above this point but there is no power or speed and CMG is pitiful I might do this short term if I'm feeling lazy to make a marker.

Up until that point the boat feels good, powerful and responsive and only looses a small amount of speed for pointing several ° higher. 

Happy to be told I'm wrong, I'm pretty new to this. 

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You're missing the point of dropping off a bit, its about building speed up which then brings the wind forward which means that you can then head up more toward the mark at the increased speed, the best sailors just seem to be able do that naturally, others like me have to work at the balance of speed and building apparent wind speed to achieve best vmg.

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6 hours ago, SCARECROW said:

Find a good hobie 16 sailor and let them have a drive.

Yep....... get lessons from those that know..... One day and the improvement will be huge

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1 minute ago, PIL66 said:

Yep....... get lessons from those that know..... One day and the improvement will be huge

and most of them will work for rum.

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On my maricat (per my avatar) to really get it to go high you've got to ease it off for speed, suddenly you find you're standing higher and still going faster.

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11 hours ago, SCARECROW said:

Find a good hobie 16 sailor and let them have a drive.

Im a good Hobie 16 sailor and would love to have a drive ;) 

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On our cat (40' daggerboard light weight but full time liveaboard so overloaded. Good sails but not laminate) we would sail happiest at 35 apparent (eyeballing from windex; didn't have instruments).

Yes, we could point higher like a monohull but it wasn't worth it.

Your speed sounds OK to low, and you are pointing quite high. Bridgedeck cats can't point as high as a good racing mono because they have so much air drag with the big house and 2 hulls.

Foils matter tremendously for that last few degrees of pointing.  Hard to imagine Schionning would draw anything other than a NACA profile but if the builder didn't do a good job then it can be an issue.

Do you have sailing instruments that give you VMG?

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On 10/15/2018 at 2:12 AM, SCARECROW said:

Find a good hobie 16 sailor and let them have a drive.

a hobie can sail in apparent..crikey and with no dagger boards, I am amazed

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Not much point in quoting apparent wind angles, better to give the angle that you tack through and then halving it to give the True Wind Angle

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nothing goes to windward like a 747 , and gentlemen don't ......................

 

seems to me you need words with the navaguesser :unsure:

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hey Dave, I have your boat's smaller brother, a Wilderness 9.3, and have always been impressed with upwind performance actually.

My boat has a hanked, fully battened job, and now a brand new main, just fitted last night actually.Its kept light, has just 1 outboard, and now sports a clean backside and daggers, plus new rigging.

I thought the daggerboards weren't too badly shaped, what would you suggest Jethro where they may be lacking in general or I should look for?

My biggest mistake is probably trying to point too high, too early before the boatspeed has been generated.Get some speed up first, and you can definitely feel it being able to point higher as you accelerate, to the point where it seems extremely high.

Getting down to board angles and stuff, I've noticed my boards will tilt back as speed comes on, with the front edge of the top of the boards up against the casing, often making it hard to raise the boards with any speed on. This is somewhere I think could be looked at, to see if there's any improvements, and next on my list.

I'd be happy to take a gun OTB cat sailor to teach me what I'm doing wrong...

 

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If you don't have good daggerboards, just run the leeward engine at 50% power. That greatly increases VMG, especially in a choppy seas.
It's cruising, after all... ;-)

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