Broad Reach in higher windspeeds / at night

[Training Wheels]

We never carry more mainsail downwind than we would carry upwind. Headsails/spinnakers go for it and power up. Headsails can provide lift to the bows. If you come to an abrupt stop at the bottom of a surf, excess main can push your bows down. Too much main up on our boat, going downwind, will want to push our stern around. Plus, what happens if you have too much main up and you have to turn upwind?

[Cheechako]

Well, that's a bit of wind. You should have the main up double reefed for control and it wont rub on the shrouds much that way also.
I used to barber haul the staysail all the time off the wind. You need some anchor points near the toerail to get it right though. Or you can use two Barber Haulers pulling in a Y shape to amend the sheeting angle when you have minimal anchor points available.

[Palarran]

Originally Posted by nfbr

What do you barber haul to that far forward?
Does your self tacker have a block on it? Could you post a pic or drawing?

I don't know what fxykty does, but I run a line from my forward to mid ship cleat, very tight. Then I tie a prusik loop into it so there is an easy adjustment. Then I just tie another line from the prusik to the jib clew and use an easy to release knot. I do this because if for some reason I need to release the line and go back to my regular jib sheet it's a one second action.

[fxykty]

Originally Posted by arsenelupiga

i know what you mean but angle of forestay at the bottom is pulling boat back. This force is equalized by hull. SO that part is not contributing to forward drive. Upper part force is under say 40 deg angle and part of horizontal component of this force is driving the boat by pulling mast forward in single point when wind blows. If no wind, this is in balance.



Say parasailor also uses mast single point to pull boat forward. Bow blocks only pull boat up in the air, only little component of that force helps driving forward .



Without main there is single point on mast that does all the work. At 10 kn boat speed these forces are enormous. With main this force is halved or thereabout.

Are there any riggers paying attention who can fact check the statement above that the forces on the jib resolve to a single point where the forestay joins the mast? Commonsense and this analysis certainly disprove that assertion https://matheo.uliege.be/bitstream/2...28UNIGE%29.pdf.

Headsail loads are distributed proportionately according to the position of the centre of effort, via mast and shrouds to the hulls at the head, to the front beam and the hulls at the tack, and via the sheet to the lead blocks and winch. All three points carry force - you can touch and feel those forces easily.

The static rig tension loads have nothing to do with how the dynamic sail loads are applied to the boat. For example, when close hauled all the static rig tension transfers to the windward cap shroud and the forestay and the leeward cap shroud is loose, plus the additional loads of the wind force on the sails shared by the forestay and sheets. On a tensioned stay the load is share equally by both points - otherwise those points would move relative to each other and it’s obvious that doesn’t happen. The absence of a mainsail does not alter the relationships of the forces acting on the rig, only the total force as there is less sail area.

A headsail provides a lifting force to the bows, due to the angle of the forestay. On a cat with minimal heeling, the lifting vector is not just forward but also up. When a monohull heels that lifting force goes negative, but it’s still not much.

Rest assured, sailing with headsail alone will not cause your mast to fail. Cruising rigs are built with massive safety factors and are stiff enough that they don’t need a mainsail to be set to prevent inverting a mast (a potential problem upwind for skinny racing rigs).

[Jim Cate]

i know what you mean but angle of forestay at the bottom is pulling boat back. This force is equalized by hull. SO that part is not contributing to forward drive. Upper part force is under say 40 deg angle and part of horizontal component of this force is driving the boat by pulling mast forward in single point when wind blows. If no wind, this is in balance.

Static loads on the forestay have nothing to do with the forward vector generated by the lift on the sail.

I believe that your analysis is wrong.

Jim

[arsenelupiga]

Originally Posted by Jim Cate

Static loads on the forestay have nothing to do with the forward vector generated by the lift on the sail.

I believe that your analysis is wrong.

Jim

i am pretty sure it is correct. There are 2 attachments of forestay on the rest of the boat + sheet. Only these 3 points can drive boat forward.

Forestay at the bow is pulling boat back, when sail out or not. Forestay on the mast does majority of pull. It has to pull the boat + compensate for extra force that is induced on forestay from bow attachment .

But hey, who cares what i say, i only have degree in physics.

[smj]

Originally Posted by arsenelupiga

i am pretty sure it is correct. There are 2 attachments of forestay on the rest of the boat + sheet. Only these 3 points can drive boat forward.



Forestay at the bow is pulling boat back, when sail out or not. Forestay on the mast does majority of pull. It has to pull the boat + compensate for extra force that is induced on forestay from bow attachment .



But hey, who cares what i say, i only have degree in physics.

A degree in physics? [emoji23][emoji23][emoji23]

[Training Wheels]

No disrespect meant, but his boat seems to defy physics!

[arsenelupiga]

Originally Posted by Training Wheels

No disrespect meant, but his boat seems to defy physics!

haha, so you are accusing me of motoring to create these tracks. Now I really feel flattered.

The other possibility is your boat has substandard design. Be honest to yourself and consider this as well.

VPLP are top designers and with lean boat one gets unexpected performance gifts.

I have done some enhancements for reaching/broadreaching that should make you question using of my engines even more when i get a chance for full unleash. However there speeds wil be beyond engine so i hope this will convince you i am legit.

[smj]

Originally Posted by arsenelupiga

haha, so you are accusing me of motoring to create these tracks. Now I really feel flattered.



The other possibility is your boat has substandard design. Be honest to yourself and consider this as well.



VPLP are top designers and with lean boat one gets unexpected performance gifts.



I have done some enhancements for reaching/broadreaching that should make you question using of my engines even more when i get a chance for full unleash. However there speeds wil be beyond engine so i hope this will convince you i am legit.

Physics should tell you that the Lagoon 400 even with no load added is not a lean catamaran, both in weight and design.

[catsketcher]

I think the OP should have a play around with their boat to see what works best for them. I also like running downwind with the genoa and screecher, wing and wing, a nice square run technique that solves any chafe and allows me to dial up the sail I want more easily by roller furling. But listen to the boat.
In my racing and coaching days I used to get people to close their eyes and listen to the boat, reducing helm pressure and then feeling when the boat was sliding along well in balance. Fast racers can do this automatically as it allows them to sail fast when looking around to do tactics. Dead downwind my boat loves just having a genny or screecher in plenty of breeze, the autopilot has it easy and she slips along. Then when I want to harden up to reach, she gets lee helm. This is her way of saying, I need more main on (so up goes the main). I used to often have to undo people's preconceptions of what they should do to their boat because of something they read. It was always better to listen to the boat and respond to it, rather than enforce your opinion onto the boat. Never fight her, always listen and get her to be smooth. In cats this is a lot harder as monos, and high performance dinghies are good at teaching you how to listen carefully to what your boat requires. Try sailing a Laser and the boat will make you listen or you will capsize. You don't need a book to tell you how to sail a particular model, it will be a good guide but the boat will need different touches depending on sea state, wave angle, apparent wind and crew ability.

Here is a fab photo of one of the best sailors in the early days, in the southern ocean, running before waves that would scare us all, no main needed for mast control, but a small storm jib set forward to pull the boat along on a square. This is basic seamanship - forward set sail to run downwind. It has been done like this for centuries. With a crew and more speed needed we could crowd on more sail but for balance and safety Chichester has it set up beautifully for deep downwind sailing.

[Training Wheels]

Originally Posted by arsenelupiga

haha, so you are accusing me of motoring to create these tracks. Now I really feel flattered.



The other possibility is your boat has substandard design. Be honest to yourself and consider this as well.



VPLP are top designers and with lean boat one gets unexpected performance gifts.



I have done some enhancements for reaching/broadreaching that should make you question using of my engines even more when i get a chance for full unleash. However there speeds wil be beyond engine so i hope this will convince you i am legit.

You make a lot of assumptions.

[arsenelupiga]

Originally Posted by smj

Physics should tell you that the Lagoon 400 even with no load added is not a lean catamaran, both in weight and design.

air flow and water flow are amazing subject to study. Behave differently at different speeds, temperature, waves, etc.

Your view seem a bit simplistic.

For example reaching and downwind, especially above hull speed boat aerodynamics does not mean much. Probably underwater hull shape does. One can see that L 400 can go also to weather if not loaded too much, so that some even do not believe the results above.

What is not to like about L 400 ?!?!

Just noticed, we are the only cat posting sub 90 degrees tack. Can do someone else as well please ?

[Jim Cate]

Forestay at the bow is pulling boat back, when sail out or not.

Ahh, I now understand why your boat is so unusually fast: you have slacked off the forestay rigging screw so that it doesn't pull back so hard...

Seriously, your analysis is not correct, but far be it for me to argue with a honest to god physicist.

I give up.

Jim

[kev_rm]

wtf - barber hauler for keeping the head sail (or staysail) "off the shrouds" ? can you provide a pic of this rig?

Originally Posted by LittleWing77

Yes! I've never understood this trend of using only one sail on a sloop. I remember reaching (more beam reaching) offshore from the Caribbean up towards the end of Long Island in 45 knots of breeze.

We were flying. The boat loved it. (Big heavy custom Little Harbour 55'). It seemed all the stars in the Universe were out that night.

Best night watch I ever stood. I can still recall the exhilaration.

Proper sail trim and balancing a boat's sail plan is essential. So yes. Reefed main up with a properly set barber-hauler (which keeps the sail off your shrouds).

+1

LittleWing77