Upwind performance of condomarans

[rom]

Originally Posted by tuskie

Seems that CE Category A maximum loading for a Seawind 1250 is 1450 kg. according to the plate affixed to recently produced hulls.

So, once fuel and water is filled from 50% to full accounting for an additional 590 kg, less than 900kg payload is available for all extra loadings; fitments, gear and people. No wonder this information is not readily available. Its very meagre for what has been touted as being designed as a long distance cruising catamaran.

this is not how CE weight calculation works, see my previous post.

[PaulinOz]

[Firstbait]

18 people, seawind must be aiming for the Indonesian market

[arsenelupiga]

Originally Posted by PaulinOz

18 people and only 1 toilet on ocean passage

[Bean Counter]

Interesting. The Seawind 1160 Lite manual has CE capacities printed but not the 1250 or 1260.

[catsketcher]

Originally Posted by django37

In the CE-lightship weight, all tanks: diesel, water and septic are 50% full.

Would like to repeat: For hull resistance for speed above hullspeed only one parameter is important: The slendernessratio ie: length divided by 3.rd root of displacment. The water dosnt care, if it has to run under the botton or around the sides. Under hull speed wetted surface is important.

That is pretty revolutionary stuff Django and not what the racing multis would have one believe. The racers I see have length to beam ratios of at least 12-1, more commonly about 15:1. I can't think of any fast racers that have gone flat and fat, they all try to get narrow waterlines on a semi circular cross section. It could be due to wave action, hull interaction or some wave making thing but I can't think of any designer of fast cats who has ever said what you did. The lee hull of a cat does get immersed heavily and it may be that this immersion and increase in drag complicates the maths. I get that theory may say that hull width is immaterial but the experiment by the racers does not back up the theory - which if it is a good theory - it should.

I have included some articles from some pretty well respected designers that talk about hull slenderness ratios. Richard Woods does talk about the dimensionless slenderness ratio but goes on to say that length to width ratios of about 12-1 are good for faster cruising cats.

Sailing Catamarans - Hull Resistance and Hull Shape Comparisons

Schionning designs are awfully quick and he tries to get the ratio to 16-1 in some really quick designs.

http://www.schionningdesigns.com.au/...manceTips0.pdf

Tony Grainger (who like Schionning has designed some of Australia's fastest multis for over 25 years) says that resistance is greater with less than about the 10:1 ratio.

https://www.graingerdesigns.net/the-...r-performance/

So I would be very happy to see a flat and fat hulled fast cat, but the guys who draw them, and make money from designing the fastest cats they can don't think it would work. Off the beach cats are thin but powerful. If fat would work someone would be building them and beating the others in F18 races. Going thinner than semi-circular doesn't seem to help - a la CSK, Myers and Hobie 16s but semi-circularish seems about right from the boats I have seen in sheds and on the water. Tornadoes, Capricorn F18s, A class, Hobie Tiger, B and Q trimaran, Sodebo etc.

In the 80s Kel Steinman designed a really fat and flat 18ft skiff. He had designed a range of fast monos. The skiff was an absolute dog and got chainsawed up. Now even in skiff sailing, the fast designs are thin. In 16ft skiffs they changed to thin hulls about 15 years ago after Greg Hyde won the Oz nationals by miles in a thin hulled skiff. Now all 16s are thin and one design. Thinner is faster when you don't plane, just like we learnt over a hundred years ago in rowing skulls and kayaks. I will race you in my kayak, you can race me in your similar length and weight fatter stand up paddle board. I did this the other day with my mate and he was nowhere near my speed, not even half.

That is not to say that fatter cats are bad - not at all. I am happy for anyone to sail anything they like, but we can't change physics. You need a wide enough hull to carry your stuff and immersing transoms a lot is bad for drag. If you can carry less you can go thinner and faster, if you want more you go fatter and slower. Your choice and my hat off to you. We all get to to the same place in the end to share an anchorage together.

cheers

Phil

[rom]

So what do we have for this seawind 1250: 3300 kg "payload" which I believe is correct and shall be compared to the same none CE load on condos (e.g. 5900 kg on mine). Their 1450 kg CE Cat A payload sounds about right as the boat has about 1500 kg of fuel & water capacity.

Someone mentioned that CE payload includes 50% water&fuel, I cannot find any source to confirm that information. I finally believe they can put whatever payload value there as long as they justify it in the documentation. Which they don't for that particular boat.

It may not seem much but is actually about the same a new Outremer 45 (their brochure only says displacement 8.7/11.7t, so I guess it is full payload). And those outremer are long distance cruisers.

18 people Cat A & 30 Cat D (manual says 32) is indeed a bit strange for small and allegedly fast cruiser.

EDIT: I found it, 2013 CE: the recommended payload on the CE marking excludes the weight of all tanks when they are FULL.

[smj]

Originally Posted by arsenelupiga

here we see gentlemen, display of strong brand love/hate. this person would even die/sink/starve, just to be close to particular brand/and away from another.



wonder what marketing approach managed to do that ?

Nah, I just like a well built catamaran.

[PaulinOz]

Quote Rom "I cannot find any source to confirm that information. I finally believe they can put whatever payload value there as long as they justify it in the documentation. Which they don't for that particular boat"

Exactly what ever they like, so apples, oranges who knows what they are quoting. But CE certification is done independently of the marketing hype by manufacturers, at least that is my belief, but I am willing to be proven wrong. If you know differently lets here about it.

So Seawind 1250 can carry 1450 Kg, does that exclude, generator, water maker, dinghy, solar panels, inverter, etc etc etc. Or are they part of the 1450 Kg. Just asking so we can actually compare apples for apples in the real world of long distance cruising boats.

[rom]

Originally Posted by PaulinOz

Quote Rom "I cannot find any source to confirm that information. I finally believe they can put whatever payload value there as long as they justify it in the documentation. Which they don't for that particular boat"

Exactly what ever they like, so apples, oranges who knows what they are quoting. But CE certification is done independently of the marketing hype by manufacturers, at least that is my belief, but I am willing to be proven wrong. If you know differently lets here about it.

So Seawind 1250 can carry 1450 Kg, does that exclude, generator, water maker, dinghy, solar panels, inverter, etc etc etc. Or are they part of the 1450 Kg. Just asking so we can actually compare apples for apples in the real world of long distance cruising boats.

I edited my previous message:
2013 CE: the recommended payload on the CE marking excludes the weight of all tanks when they are FULL.

So for the seawind 1250: 1450 kg + water + fuel (+ safety & sails ?) ~= 3300 kg.

Per L440 documentation the CE light displacement includes sails & safety gear.

12150 kg being the CE light displacement per L440 brochure.

[Bean Counter]

It would be interesting to see the attached form filled out for a Seawind 1250.

[44'cruisingcat]

Originally Posted by rom

So what do we have for this seawind 1250: 3300 kg "payload" which I believe is correct and shall be compared to the same none CE load on condos (e.g. 5900 kg on mine). Their 1450 kg CE Cat A payload sounds about right as the boat has about 1500 kg of fuel & water capacity.

Someone mentioned that CE payload includes 50% water&fuel, I cannot find any source to confirm that information. I finally believe they can put whatever payload value there as long as they justify it in the documentation. Which they don't for that particular boat.

It may not seem much but is actually about the same a new Outremer 45 (their brochure only says displacement 8.7/11.7t, so I guess it is full payload). And those outremer are long distance cruisers.

18 people Cat A & 30 Cat D (manual says 32) is indeed a bit strange for small and allegedly fast cruiser.

EDIT: I found it, 2013 CE: the recommended payload on the CE marking excludes the weight of all tanks when they are FULL.

So, it does seem that someone has been dishonest here.

First Tuskie said he couldn't find load information on the Seawind1250. It took me all of 2 minutes.

Then, when he didn't like the number from the owner's manual, he miraculously produces a number that suits him much better.

THEN, he tells a misleading story about CE load calculations.

Pants on fire?

[44'cruisingcat]

Originally Posted by arsenelupiga

18 people and only 1 toilet on ocean passage

Have you ever tried to verify anything, or do you just spout the first garbage to enter your head?

[44'cruisingcat]

So, after all the lies, drivel and misinformation, it turns out the Seawind1250 has adequate load carrying capacity for it's intended purpose. Long distance cruising.

Anyone going to attack the Lightwave 45?

[arsenelupiga]

Originally Posted by 44'cruisingcat

Have you ever tried to verify anything, or do you just spout the first garbage to enter your head?

you said any boat with more than 1 toilet is charter boat . As you displayed such a passion for Seawind 1250, i assumed is 1 toiliet boat. Even with 2, I find this ridicolous for 18 people. Or you saying there is option with 3 toilets or even 4, 5 6 ?

So i thought you are promoting Orams, but now Seawind passionate supporter that are mostly slower that Lagoons as per ARC results. So what is going on ?

FYI : seawind upwind was slover than Lagoon 400. Not sure whether 38 or 1250. Sneaked from behind, however continued to lose against Lagoon and gave up after 1 your of 'chase'.