Cruising cat - sub 90 degrees tack upwind

[Seaslug Caravan]

Originally Posted by 44'cruisingcat

1: Not 600 kg, or anything like it.

2: Reduced draught.

3: Greatly reduced sailing around at anchor.

4: Significantly less wind against tide hassles at anchor. We once spent a week repairing a friends minikeel from damage sustained when it got chain wrapped around it.

5: Significant performance gains on virtually all points of sail. The windward gain is possibly the least of it. A minikeel boat is sort of like a daggerboard boat with boards stuck partway down. Not really what you want on most points of sail.

6: Greater safety in extreme conditions. As pointed out above, reduced grip in big waves can help prevent capsize.

7: Safer for bar crossings. A cat with boards up is like a surfboard. It'll tend to keep pointing down waves, rather than turning side on.

Ha, that’s funny.

1/ yer probably not 600kg possibly more carrying capacity with the added buoyancy of mini keels

2/ nah, most offshore cats have saildrives so need the protection of mini keels to be safe when drying out. Outboards more normal on coastal boats.

3/ now that is correct unless you have a wing mast.

4/we spent 2 weeks repairing centre boards and cases after a friends accidental grounding. ( tore the case open as well and took on water)

5/ when you start racing your boat you will see that even deep reaching boards half down is a good thing for control/steerage. Yes upwind very little difference. Correct.

6/ that’s old school. Long debunked old wives tale. Lot of aerated surface water providing little grip. Fine performance hulls especially chine ones like yours have lots of grip and act like cruising boats with keels.

7/ nah, steering around a buried bow is the main issue with surfing. Stalled water flow over rudder the second. More likely on a fine bowed performance hull with boards. Remember the video of the Perry 43 entering the GC seaway.

Regards.

[44'cruisingcat]

Originally Posted by Seaslug Caravan

Ha, that’s funny.



4/we spent 2 weeks repairing centre boards and cases after a friends accidental grounding. ( tore the case open as well and took on water)

Yeah, two weeks. Of course it was. I guess some people will let anyone work on their boat.

Grounding will damage minikeels as well. And it's far more likely since you're basically stuck with them all the time.

There's really not much excuse for grounding daggerboards. You can raise them, you know?

Of course there may be an alternate universe where daggerboards offer no advantages. They probably wouldn't build boats with them there. However, in real life....

[malbert73]

Ok not a catamaran but let me share some experience with having both a stub keel and a deep foil on my boat (K/CB). I can tack at 70-80 degree angles in my mono but go relatively slowly. Anyone can pinch up to their sheeting angles and certainly in flat water it’s effective when breeze is up. But best VMG for me is often more at, or more than 90 deg angles especially in rough seas.

Now, certainly my boat points fine with its stub keel drawing just under 5 feet. But if I lower my relatively high aspect centerboard the difference is nearly 10 degrees of pointing with no loss of speed through water (which means better VMG)
There is no way stub keels allow better pointing. I think more likely the Lagoon 400 just doesn’t accelerate as much as performance daggerboard cats which can’t tack at less than 90 degrees since they go too fast and 30 degree apparent wind means more than 45 degrees true wind angle.

[arsenelupiga]

Originally Posted by 44'cruisingcat

Then I'll try to explain it to you again.

The slower you sail, the smaller the difference between TWA and AWA. So if you sail the same apparent wind angle, but slower, your tacking angle will be reduced.

This is why it's easier to achieve the fabled 90' tacks on slow boats.

and i will explain to you again. This is not about specific angle but leeway when climbing high. It is way less than suburban legends suggest. Heavier cat has this strength, that comes really handy sailing upwind, as it harder to cross hull speed.

This gives me idea to design new gennaker that will also sail inside shrouds, so I will sacfrifice 10 % of gennaker area for better upwind in light airs where L400 is underpowered.

[arsenelupiga]

Originally Posted by Jim Cate

This. Plus, fouling on the mini keels will increase drag and reduce lift so leeway will increase.

Jim

yeah, ask around what mess when barnacles grow inside dagger trunk

[arsenelupiga]

Originally Posted by fxykty

Your first fixed keel statement is not correct as you are using your optimised n=1 example to generalise. If it was true, many more catamarans of your sort would be sailing in the conditions and directions that we commonly see them motoring.

Physics do not lie: the foil profile and geometry of a low aspect fixed keel have more drag and lower efficiency than a high aspect daggerboard of the same size.

Outremer AFAIK has not made any boats with fixed keels. But Larouge (sp?) has a mixture of fixed keels and daggerboards on his designs. His comment is that for a small performance and safety hit the fixed keel gains interior space, simplicity for those who consider lifting and dropping daggerboards to be a hassle, and slightly less structural weight (3 of your points above). Note that Larouge designs are relatively light, semi-custom, performance cruising catamarans.

Break and possible hull damage - same problem for fixed keels.

Deck space cluttered? It’s one extra control line and clutch per side, out of the 10 or so already there.

You didn’t mention safety in bigger seas - the ability of a daggerboard boat to raise its leeward daggerboard and reduce tripping hazard.

Nor the ability of daggerboard boats, especially if combined with lifting rudders, to go into shallower waters and to comfortably beach, without being up on stilts. Not a benefit of ours unfortunately, unless it’s a sloping beach, due to our fixed rudders and skegs sticking down about 30cm more than our hulls.

Our boat is special only because we are loaded to factory recommended weight.

[arsenelupiga]

Originally Posted by Factor

Because they are better upwind, there is simply no way a Low Aspect Ratio Foil can perform as well as a HAR foil. Thats not me talking that is NACA, then again the study of foils has only been their focus for about 100 years.

Because they are better downwind, less drag,

Because they are better in severe conditions, less tripping danger.

I have sailed a SW1160 and Sw1190, pretty much the same boat, the 1190 (the one with daggerboards) is demonstrably quicker and sails higher, that doesn't make the 1160 a bad boat, just makes the 1190 a better performing boat. Notably boat boats are reasonably light and have slim hulls

But if you sail heavy and fat hulls, and you sail slow you can get tight angles, but in the real world when dealing with current tide wave action on hulls fat bows that move with the sea rather than through it you wont go anywhere.

And anyway, what would the people who designed your boat know, when tasked with designing a high performance gunboat they thought that daggerboards might work. (See attached reference from their website) When tasked with designing a 77foot Outremer they did the same. Still what would they know, or indeed what would Chris White, Jeff Schionning, Tony Grainger, Loch Crowther, Rachel Pugh Design, et al know. What would NACA know?

Mini keel boats are not by definition bad, indeed for most people they are probably the best choice, BUT performance to windward and downwind is not their forte.

Gunboat is bankrupt company as far as i know so would not worry too much. VPLP seem to be doing quite well including designing lagoons, latest outremer and fastest boats on earth.

Daggers are faster, but keels are underestimated

[arsenelupiga]

Originally Posted by Factor

Do you have to bear away to tack? It seems so from your track diagram?

My AP sucks and plays games when tacking in windwane mode. Cant be bothered to check manual. Presume needs recalibration.

[arsenelupiga]

Originally Posted by 44'cruisingcat

1: Not 600 kg, or anything like it.

2: Reduced draught.

3: Greatly reduced sailing around at anchor.

4: Significantly less wind against tide hassles at anchor. We once spent a week repairing a friends minikeel from damage sustained when it got chain wrapped around it.

5: Significant performance gains on virtually all points of sail. The windward gain is possibly the least of it. A minikeel boat is sort of like a daggerboard boat with boards stuck partway down. Not really what you want on most points of sail.

6: Greater safety in extreme conditions. As pointed out above, reduced grip in big waves can help prevent capsize.

7: Safer for bar crossings. A cat with boards up is like a surfboard. It'll tend to keep pointing down waves, rather than turning side on.

i have 600 kg from Lerouge site, this is guy building very fast ocean going cats with keels and daggers. His opinion for cruising fixed keels better.

I was looking at buying one of his fixed keel models. 43 feet. Owner said, number of 350 NM days, which equates to 14.5kn average (!!!) so fixed keel not that slow.

[arsenelupiga]

Originally Posted by malbert73

Ok not a catamaran but let me share some experience with having both a stub keel and a deep foil on my boat (K/CB). I can tack at 70-80 degree angles in my mono but go relatively slowly. Anyone can pinch up to their sheeting angles and certainly in flat water it’s effective when breeze is up. But best VMG for me is often more at, or more than 90 deg angles especially in rough seas.

Now, certainly my boat points fine with its stub keel drawing just under 5 feet. But if I lower my relatively high aspect centerboard the difference is nearly 10 degrees of pointing with no loss of speed through water (which means better VMG)
There is no way stub keels allow better pointing. I think more likely the Lagoon 400 just doesn’t accelerate as much as performance daggerboard cats which can’t tack at less than 90 degrees since they go too fast and 30 degree apparent wind means more than 45 degrees true wind angle.

Attachment 236080

thanks for data point. So with keel you must have at least 10 deg leeway.

Quick background :
-----------------
Suburban legend that lives on internet: Cats like L 400 are advised to sail upwind at 50 app. Any higher, leeway goes up exponentially because of windage.
--------------------

In last tack i posted here i managed 2 kn VMG in 8 kn true at 91 degress tack over ground. Using 50 app in 8 kn wind it is impossible to do 2 kn VMG !

So now you see I found way to improve VMG for L 400 beyond believable limits!

And this is what is all about. Not daggers vs fixed keel, as some appear to think. It helps me to plan my next sail that will be more upwind centered as before i was under impression that leeway will be ridiculous and no point trying upwind with gennaker. Now i am hopeful leeway with gennaker will be in light winds maybe 3 degrees.

[arsenelupiga]

Originally Posted by Seaslug Caravan

Ha, that’s funny.

1/ yer probably not 600kg possibly more carrying capacity with the added buoyancy of mini keels

2/ nah, most offshore cats have saildrives so need the protection of mini keels to be safe when drying out. Outboards more normal on coastal boats.

3/ now that is correct unless you have a wing mast.

4/we spent 2 weeks repairing centre boards and cases after a friends accidental grounding. ( tore the case open as well and took on water)

5/ when you start racing your boat you will see that even deep reaching boards half down is a good thing for control/steerage. Yes upwind very little difference. Correct.

6/ that’s old school. Long debunked old wives tale. Lot of aerated surface water providing little grip. Fine performance hulls especially chine ones like yours have lots of grip and act like cruising boats with keels.

7/ nah, steering around a buried bow is the main issue with surfing. Stalled water flow over rudder the second. More likely on a fine bowed performance hull with boards. Remember the video of the Perry 43 entering the GC seaway.

Regards.

some truths here

[smj]

Originally Posted by arsenelupiga

yeah, ask around what mess when barnacles grow inside dagger trunk

If barnacles did grow in the daggerboard trunk, which from my experience isn’t a problem, how would that affect speed or leeway?

[Factor]

Originally Posted by arsenelupiga

of his fixed keel models. 43 feet. Owner said, number of 350 NM days, which equates to 14.5kn average (!!!) so fixed keel not that slow.

ROFLMAO 350 NM days, thats averaging 15 knots in 43 foot boat. Really LMAO

[arsenelupiga]

Originally Posted by Factor

ROFLMAO 350 NM days, thats averaging 15 knots in 43 foot boat. Really LMAO

that is what owner said, we were potential buyers. Boat had wing mast and fixed keels and single motor and was all about sailing. But inside too small for us. We have done thorough research and happy with what we ended up with.

[arsenelupiga]

Originally Posted by smj

If barnacles did grow in the daggerboard trunk, which from my experience isn’t a problem, how would that affect speed or leeway?

you are right. No impact. But it is something to think about if daggers left unused for longer, i heard.