Why Do Catamarans Motor Nearly 100%

[44'cruisingcat]

Originally Posted by StuM

Why suddenly bring in VMG. You weren't interested in it when you claimed your "upwind" speed. 2Winds has just shown that he too can get the same boat speed v TWS upwind which you said couldn't be done in his type of boat.

Yep, that was my point.

[Polux]

Originally Posted by StuM

Why suddenly bring in VMG. You weren't interested in it when you claimed your "upwind" speed. 2Winds has just shown that he too can get the same boat speed v TWS upwind which you said couldn't be done in his type of boat.

What was in discussion was the upwind performance of condo cats, that I said it was poor and makes motoring upwind if not a necessity a thing that most do.

Going directly upwind what counts is not the angle neither the speed but a combination of the two. The performance upwind is measured by the VMG that take into account those two factors.

I said that it cannot be made on condo cats sailing upwind. The VMG of less than 1K shows that the boat is not sailing upwind, at least on any practical way. Sailing upwind is making way against the wind.

Regarding the speed a boat can do or not you can be sure that a Boat Polar published by the manufacturer never shows under performances. They tend in fact to be a bit optimistic in what regards performances. Here you have another from another Lagoon, a 440. They show clearly what is the performance this type of boats can have sailing upwind.


We can see that the Lagoon only makes a decent speed "upwind" at 80º real TRW angle and that is consistent with that speed posted. But sailing "upwind" with an angle of 80º does lead to a very poor VMG. If the Lagoon sails closer to the wind the speed falls drastically and at 50º, or even 60º it is much smaller. Those are the angles that are normally used by monohulls, or performance cats to sail upwind.

[44'cruisingcat]

Anyway, here's a video of us sailing upwind. Overloaded, sails flogged out (26,000 miles on them now) but still able to make a little progress to windward.



I should state, our speed/log is in the port hull, so on port tack it reads a little high. (Reads a little low on starboard.)


But the SOG can be seen on the chartplotter, reading around 9 knots.

https://www.youtube.com/watch?v=34qgJRprAlE

[colemj]

One has to be careful with catamaran polars - realizing that the y-axis is rpm, not windspeed….

Mark

[44'cruisingcat]

Originally Posted by colemj

One has to be careful with catamaran polars - realizing that the y-axis is rpm, not windspeed….

Mark

Ah yes, forgot that. Seem to keep forgetting to start my engines too...

[weavis]

Originally Posted by 44'cruisingcat

Ah yes, forgot that. Seem to keep forgetting to start my engines too...

hee hee.

[weavis]

Was good to the video again 44. I do like the positioning of your instruments.

[Palarran]

Originally Posted by Dockhead

Quote:
Originally Posted by Palarran View Post
this thread from the first post was only meant to cause negativity on the forum.



You guys should have read the OP more carefully. The OP likes cats, is considering buying one, and is trying to decide whether it even needs sails or not -- whether a power cat might be better.

The title was provocative, unintentionally, I think.

Dockhead, I read it perfectly. When my wife asks me really stupid questions, usually I let it go by. Taking that question that is OBVIOUSLY not true - or even close, and posting it on this forum is still only meant to cause a reaction, one that is predictable. The statement stands "Why do catamarans motor nearly 100% of the time". No real observation can support this statement. They don't. That should have been the answer. If the thread would have been "Do catamarans motor more than monohulls" it wouldn't have bothered me and would have simply joined the 10 like themed threads started by monohullers over the years.

[Barra]

Originally Posted by 44'cruisingcat

Anyway, here's a video of us sailing upwind. Overloaded, sails flogged out (26,000 miles on them now) but still able to make a little progress to windward.



I should state, our speed/log is in the port hull, so on port tack it reads a little high. (Reads a little low on starboard.)


But the SOG can be seen on the chartplotter, reading around 9 knots.

Nice sailing conditions 44. Try walking around a mono with a camera in your hand while sailing at 30 odd awa and 9 knots

Also thanks for clearing up why Im faster on port tack also

Polux is right on one thing though and thats the pointlessness of manufacturer polars IMHO especially the bit about ignoring seastate on the upwind angles.

[2Wind]

These Polar Plots are theoretic computer derived models only.


In real life on my boat, I am a little better than the polar on a genuine upwind leg "hard on", a little slower than the polar on a broad reach, especially at higher wind strength and about the same as the polar when deeper down wind or on a deep reach.

[malbert73]

Originally Posted by 44'cruisingcat

Anyway, here's a video of us sailing upwind. Overloaded, sails flogged out (26,000 miles on them now) but still able to make a little progress to windward.



I should state, our speed/log is in the port hull, so on port tack it reads a little high. (Reads a little low on starboard.)


But the SOG can be seen on the chartplotter, reading around 9 knots.

Right, but even though yours is a cruising cat, you're being too modest. Much higher tech and lower weight build, and -gasp- daggerboards!! Much different than condo cats. yours looks like a blast to sail, since a lot of the design must have actually been geared around sailing. What a concept!


Sent from my iPad using Cruisers Sailing Forum

[44'cruisingcat]

Actually, it's pretty low tech. There's not a single strand of carbon fibre in it! Just balsa core and fibreglass. There's even plywood in the fitout.


But you're right, it is fun to sail, and the boat was designed to sail.

[Polux]

Originally Posted by Palarran

...The statement stands "Why do catamarans motor nearly 100% of the time". No real observation can support this statement. They don't. That should have been the answer. If the thread would have been "Do catamarans motor more than monohulls?" ....

Yes I agree. That should have been the title of the thread and since the vast majority of catamarans are condo cats that would be probably true in a generic way, at least in what sailing potential of the boats on all points of sail.

But not only boat's sailing potential is part of the equation, sailors are too and many, specially charters, chose cats over monohulls over the condo interior and they cannot care less about sailing: Just wanting to enjoy life on nice cruising grounds.

Some charters that chose monohulls have a similar cruising, non sailing program and just want to reach cruising spots as fast as they can. Those only chose a monohull over a multihull because multihulls are more expensive.

[Polux]

Originally Posted by 44'cruisingcat

Actually, it's pretty low tech. There's not a single strand of carbon fibre in it! Just balsa core and fibreglass. There's even plywood in the fitout.

That is not the point, the point is the difference in price between a condo cat and a performance cat and that is very significant.

[Polux]

Originally Posted by 44'cruisingcat

Anyway, here's a video of us sailing upwind. Overloaded, sails flogged out (26,000 miles on them now) but still able to make a little progress to windward.



I should state, our speed/log is in the port hull, so on port tack it reads a little high. (Reads a little low on starboard.)


But the SOG can be seen on the chartplotter, reading around 9 knots.

Very nice sailing. By the plotter you are doing about 8.5/8.7K sog at 27º apparent or so, and i would say that you should have some current helping you. Anyway a very good performance but on almost flat water and it is very rare to have that sea condition with so much wind.

That's upwind with waves that cats lose more speed than fast monohulls, with two hulls hitting waves instead of one.

I will be looking at the ARC again to compare the performance of fast performance catamarans with the one of fast performance monohulls on an offshore passage. You are welcomed on the thread that is already opened. Some very fast cats there, including a brand new Outremer 51.