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arsenelupiga · 27-03-2021, 13:16

Quote:

Originally Posted by GRIT

I'll agree that sail sizes, and boat weights are often listed incorrectly. But as SMJ said, you can add sail to any boat, so any chart has to use a certain standard. That standard, of course, would have to be generally accepted numbers, which would be either the designer's numbers, or the manufacturer's numbers.

I would suggest the discrepancy between your two sail area examples might simply be that one is a Genoa, and the other a Blade, or some such. Though it says Genoa on both adverts, I find most people are lazy with nomenclature (my self included). Not only that, there may be an issue with translation, as Lagoon is French after all.

To say there's a fault in the chart, due to the fact that you have larger sails than the average Lagoon, is silly. I'm pretty sure the chart was intended to represent the average boat of each model, as sold from the factory. One simply cannot list every possibility on a chart.

If you saw someone say the displacement numbers were without engines, I'm sure they were simply trying to cover their lies, regards "optimistic" displacement numbers. Even then, I'd be very surprised if anyone would have the gumption to say their boat weighs XXX, without the engines. Engines, after all, are not generally considered "optional" equipment.

I commend you on your research, and testing on your own boat, but your results do not represent the average lagoon. Neither the sail area, nor the weight of your boat is representative of the norm, for that builder. And no matter how fast YOUR boat goes, the average lagoon is not considered a fast boat.
Horses for courses, I'd be happy with a lagoon, but I wouldn't be fast.

Cheers.
Paul.

It is an error, confirmed with Incidence, maker of sails for lagoons and many other brands. I know is hard to believe but it is true as I have measured mine and is actually 35m2 although it say in my manual 28m2.

Regarding weights, i dont want to mention brand because i am not 100 % sure any more - been 10 years - but they were selling boat with optional diesels, so you could buy it without diesels and be puristic sailor. Kind of makes sense but throws spreadsheet out of balance.

All I am saying is these numbers taken from add material directly will have these types of errors and decisions based on these numbers will not be optimal. Unfortunately, the only way to gauge the boat is to test sail it - not cheap.

arsenelupiga · 27-03-2021, 13:26

Quote:

Originally Posted by Tupaia

I wasn't aware that balance made an 11 metre model. ??

It doesn't achieve double digit speeds in any wind strength so hardly a quick boat.

they make 11m, i saw adds. I dont care if it is fast but wanted to demonstrate importance of stiff boat and that one can use gennaker for upwind quite successfully if boat is stiff enough. This is not represented in that spreadsheet either as some regard upwind performance in light winds as pinnacle of sailing.

This boat, if these polars are not fantasy, sails with gennaker at 27 app and doing 4.3 VMG directly against wind in 8 kn true. HUH! That is better than CC44 rocket.

smj · 27-03-2021, 14:16

Quote:

Originally Posted by john manning

I think you should take the advice of Fxykty in these posts. All yachts are a compromise and you have to sacrifice something. Limiting the loads on your yacht make it more comfortable.

My comment on your goal is why are you thinking fast. If you extend your argument to its maximum, just fly to the destination and charter.

I own a heavy catamaran (Prout Escale). I used to try to sail this fast, actually getting to 11kts once. I now sail it between 6.5 and 8kts, for comfort. I have recently bought a heavy displacement 48ft timber yacht (approx 30 tonnes). I plan to slow down even more. With weather forecasting options today you can be confident of the next 7 days of weather and with satellite communications you can get weather updates daily, while at sea, and re-route your course to suit.

Is your goal sailing or are you just travelling somewhere.

For me personally the advantage of the performance catamaran is the ability to sail in light airs while all others are motoring. It’s not all about the top speed

smj · 27-03-2021, 14:19

Quote:

Originally Posted by arsenelupiga

they make 11m, i saw adds. I dont care if it is fast but wanted to demonstrate importance of stiff boat and that one can use gennaker for upwind quite successfully if boat is stiff enough. This is not represented in that spreadsheet either as some regard upwind performance in light winds as pinnacle of sailing.

This boat, if these polars are not fantasy, sails with gennaker at 27 app and doing 4.3 VMG directly against wind in 8 kn true. HUH! That is better than CC44 rocket.

I don’t think Balance ever made an 11m cat, in fact I’m sure they didn’t.

44'cruisingcat · 27-03-2021, 14:37

Quote:

Originally Posted by smj

For me personally the advantage of the performance catamaran is the ability to sail in light airs while all others are motoring. It’s not all about the top speed

Me too!

arsenelupiga · 27-03-2021, 15:07

Quote:

Originally Posted by smj

I don’t think Balance ever made an 11m cat, in fact I’m sure they didn’t.

oops sorry my bad, it is actually Excess 11, benetau boat. This polar is for pulse line of sails.

fxykty · 27-03-2021, 21:48

Quote:

Originally Posted by arsenelupiga

oops sorry my bad, it is actually Excess 11, benetau boat. This polar is for pulse line of sails.

7 knots upwind, ROTFLMAO.

Those polars are absolute BS for upwind and downwind as well; reaching at those boat speeds possible in flat water only. 9K kg displacement is a hell of a lot for a not even 40 foot catamaran. Those very wide hulls will need lots of power to overcome their hydrodynamic drag, as well as the aerodynamic sh*tstorm above the waterline.

Internal only as I’m sure they know that no one except the very gullible would believe those numbers.

I would take passage stats as the only real world way of presenting offshore cruising speed potential (well, actual). And it needs to be a mix of passages that showcase a variety of courses, not just the often quoted downwind slide of the ARC.

As a side note, on one’s own boat that’s also the best way to compile a realistic set of polars. Speaking of which, when using the update polar from NMEA data option in OpenCPN, does it continually overwrite the current data with new data? How long should one update with NMEA data?

arsenelupiga · 27-03-2021, 22:45

Quote:

Originally Posted by fxykty

7 knots upwind, ROTFLMAO.

Those polars are absolute BS for upwind and downwind as well; reaching at those boat speeds possible in flat water only. 9K kg displacement is a hell of a lot for a not even 40 foot catamaran. Those very wide hulls will need lots of power to overcome their hydrodynamic drag, as well as the aerodynamic sh*tstorm above the waterline.

Internal only as I’m sure they know that no one except the very gullible would believe those numbers.

I would take passage stats as the only real world way of presenting offshore cruising speed potential (well, actual). And it needs to be a mix of passages that showcase a variety of courses, not just the often quoted downwind slide of the ARC.

As a side note, on one’s own boat that’s also the best way to compile a realistic set of polars. Speaking of which, when using the update polar from NMEA data option in OpenCPN, does it continually overwrite the current data with new data? How long should one update with NMEA data?

you are probably right. Considering that VPLP is behind design, i do want to verify these numbers, as this will drive my future boat swap direction.

mglonnro · 28-03-2021, 02:02

Quote:

Originally Posted by arsenelupiga

you are probably right. Considering that VPLP is behind design, i do want to verify these numbers, as this will drive my future boat swap direction.

Excess/Beneteau does provide a nice tech document about the underlying performance considerations. Real-life actual data would obviously be a good compliment.

arsenelupiga · 28-03-2021, 02:34

Quote:

Originally Posted by mglonnro

Excess/Beneteau does provide a nice tech document about the underlying performance considerations. Real-life actual data would obviously be a good compliment.

do you have that doc to share ?

mglonnro · 29-03-2021, 01:31

Quote:

Originally Posted by arsenelupiga

do you have that doc to share ?

I sent you a private message

double u · 29-03-2021, 02:23

"...aerodynamic sh*tstorm above the waterline."

That's a good one! (& imho applies to nearly all the cats we saw between france & Tahiti!)

**Tupaia** · 29-03-2021, 03:16

Quote:

Originally Posted by double u

"...aerodynamic sh*tstorm above the waterline."

That's a good one! (& imho applies to nearly all the cats we saw between france & Tahiti!)

Very few designers address this especially if the boat is destined for charter, where galley up, upright windows and berth equivalence is more important than sailing qualities.