Upwind performance of condomarans

[sailjumanji]

Originally Posted by indimini

Sailjumanji, performance was slightly better on our second sail after we reset the block on the jib to give up a bit more depth and control over the leech flutter.

It was great having you on board along with all the others with race experience. I picked up some great trim tips I hope to take advantage of this season on the Chesapeake.

Thanks Bob. You have a really nice boat. I wasn't expecting the performance, especially with not getting the main higher. Apparently I should have recorded everything on my phone! Give me a heads up, and i might come up to crew. Laurie says to tell Debra hi!

[rom]

Originally Posted by BambooSailor

For what it is worth: no track, but here is an example of Lagoon 421 fully loaded with fuel (178 gal), water (184+ gal) and provisions for 8 people for a week, in light winds, with standard genoa and mainsail, fixed props. I previously posted this on another thread.
Admiral prefers heavier boat if it means more comfort underway and at anchor, even if the price is upwind performance.

Hey Bamboo, thanks for sharing. Picture quality is not very good though and I seem to read 5.3 kts boat speed with 8.5AWS @ 30°AWA ?? but that doesn't make sense ...

[Barra]

Originally Posted by rom

Hey Bamboo, thanks for sharing. Picture quality is not very good though and I seem to read 5.3 kts boat speed with 8.5AWS @ 30°AWA ?? but that doesn't make sense ...

yeah i cant read it at all but hes sailing quite a bit faster than TWS on those numbers. Hell of an effort

[rom]

Originally Posted by Barra

Combo of the squaretop and the better shape added up to 1.5 knots boatspeed and higher pointing so well worth doing.

Can you explain what is a "better shape" ? And if one was to buy a new main sail for a condomaran, willing to improve pointing, what advice would you give ?

[sailjumanji]

RE: the picture, is that boat speed (i.e., thru the water) or is it GPS speed (over ground)? GPS speed can be heavily influenced by current. (I noted that on Bobs boat the day of our test sail - sometimes boat speed read higher and and the other direction would read lower than GPS, being influenced by current.) Older Raymarine instruments also have a correction factor that needs to be input, although I am not sure about the ones shown.

Finally, check the rpm's! Ha ha

[Barra]

Originally Posted by rom

Can you explain what is a "better shape" ? And if one was to buy a new main sail for a condomaran, willing to improve pointing, what advice would you give ?

I mean a better shape compared to the old cross cut dacron sails that had bagged out and stretched.

Going to wind good sail shape makes a big difference and by going with lower stretch options you get to keep that designed shape for longer. Triradial cut allows for a slightly better aerodynamic shape to be achieved that is more efficient.

I would say investigate a squaretop main for sure as it will improve your windward sailing. Polyester laminate sails are a good value option if wanting some longevity to that shape but I think they are maxed out at under 44 feet for a cat load wise so you might have to look at more expensive laminates or hydranet at your size. There are a tonne of threads on sail materials here and sailing anarchy.

[Scaramanga F25]

To be fair of 6 sailboats I have owned 2 were roomy cruising "monohulls with long or full keels " and they do not point any better.

To point in ANY sailing vessel you need deep fins or deep/long dagger boards.

[rom]

Originally Posted by Barra

I mean a better shape compared to the old cross cut dacron sails that had bagged out and stretched.

Going to wind good sail shape makes a big difference and by going with lower stretch options you get to keep that designed shape for longer. Triradial cut allows for a slightly better aerodynamic shape to be achieved that is more efficient.

I would say investigate a squaretop main for sure as it will improve your windward sailing. Polyester laminate sails are a good value option if wanting some longevity to that shape but I think they are maxed out at under 44 feet for a cat load wise so you might have to look at more expensive laminates or hydranet at your size. There are a tonne of threads on sail materials here and sailing anarchy.

ok, let's put it differently. I know about old bags vs new sails, I understand carbon vs. polyester. etc ...

I have an rather new genoa, North triradial. So because it's new and not cheap it is good ? no. Come on, can't you be more technical than that ?

I want to explain the sail maker what's wrong with my main sail when the time comes to buy a new one, and it's not just that it's getting old. It's shape is pretty much the same as it was made 5 years ago I would bet, and it is just not good, IMO.

I have asked already but to know answer. I am especially wondering about the draft (depth ?) in the main sail, batten tension and so on.

[rom]

Originally Posted by Scaramanga F25

To be fair of 6 sailboats I have owned 2 were roomy cruising "monohulls with long or full keels " and they do not point any better.

To point in ANY sailing vessel you need deep fins or deep/long dagger boards.

Interesting, but .. than what ?

[Barra]

Originally Posted by rom

ok, let's put it differently. I know about old bags vs new sails, I understand carbon vs. polyester. etc ...

I have an rather new genoa, North triradial. So because it's new and not cheap it is good ? no. Come on, can't you be more technical than that ?

I want to explain the sail maker what's wrong with my main sail when the time comes to buy a new one, and it's not just that it's getting old. It's shape is pretty much the same as it was made 5 years ago I would bet, and it is just not good, IMO.

I have asked already but to know answer. I am especially wondering about the draft (depth ?) in the main sail, batten tension and so on.

Im not a sail maker rom and your asking very specific questions to your boat so no "i cant be more technical than that" sheesh!

What was right for my boat and requirements will be different to yours and a good sailmaker will get you what you specifically need.

Ill take that bet though. After 5 years your dacron main will have lost a huge amount of shape and ill wager its your battens keeping what shape there is left.

[Mr B]

Well that was an interesting read,
I was hoping to get some info on sailing upwind on a Cat,
I was very dissapointed,
One thing I do know, The only way to know if your overloaded is to pull your boat out of the water and weigh it, Then subtract that weight from the Fully loaded Specs for the boat,
I know mine is overloaded as it sits 2 inches above the plimsol line, Fully loaded,
With full tanks and 35 gallons of extra fuel on board, Extra fuel was Plan B, Black tank is empty,
It had 3 of every thing, brand new on Board, Just in case some thing Failed,
Its the way it was when I bought it,

Cheers, Brian,

[catsketcher]

The necessary sail shape will be dependent on the boat. A really racey cat will have very flat sails that operate at very low apparent angles. They will have tight leeches and little twist.

Your new genoa should have the draft still where the designer put it. The camber will not change markedly as the wind increases. As the sail gets older, the camber changes. The max draft usually moves aft and the sail gets fuller (which is exactly what you don't want) as the wind increases.

A nice new main will be worked out for your boat. A slower cat will usually have a fuller main as it is operating in power mode more often and not pointing as high as a racing cat. Same with a genoa - you, and I, want a genoa which is easy to steer to (not too flat up front), keeps the max draft at about 40% or so, has a nice flattish leech, doesn't increase in depth in more wind and only gets slightly more full as you go up the hoist (sails are fuller up high).

I had a friend who got a racing genoa made for his slowish tri - it was terrible. Awfully flat, it would have been great for a Farrier Carbon tri but way too flat to get the heavier, draggier tri going well. Nice sail for one type of boat but wrong design for a slower cruiser.

So take some pics of your main and send it to the sailmaker. Do this in light and heavy winds. My guess is that the draft is aft more than it should be and that it gets much fuller in big winds.

cheers

Phil

[Just Another Sa]

Originally Posted by rom

I want to explain the sail maker what's wrong with my main sail

I am especially wondering about the draft (depth ?) in the main sail, batten tension and so on.

To get an answer to the first question you need to show photographs (digital is fine) to your sailmaker combined with info about readings of wind instruments at the time those photos were taken. Pics should show leech tension as well as draft of sail, therefore one from below or from top of mast (drone would help to take one) and other one from behind the boat (drone indeed). The sail should have a lot of tuffs all over it to indicate flow around it, in addition to the shape.
Even better to get a knowledgeable person (sailmaker will do) on board while sailing to help you with best trim and following that comments of the sail shape. The best shape and batten tension is not independent on sailing conditions, point of sail and wind strength and sea state.
In light air you want more depth near top even for windward sailing and in heavy conditions much flatter shape there.
When seastate or unclean hulls causes a lot more hull drag you need more lift force with lower center of effort than in flat seas with clean bottom. More draft overall helps with this in the former case and you have to point less to keep the boatspeed still reasonable.

2nd question requires for you to look what the tuffs and tell tales are doing. It's not possible to describe proper draft in isolation without significant personal experience of the exact same type of boat. And it's still dependent on conditions.

[rom]

Thank you guys, that is the kind of useful information I wanted to discuss. In the end it's got to be a discussion with the sailmaker. ok. Hopefully I will manage to have them more involved than they were for the genoa.
Just FYI and FWIW, I believe my boat deserves a flatter main sail than original. I suspect there will be a gain in upwind ability and no such much loss if any at all at other point of sail.