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Sheeting for canting mast


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I'm thinking of setting up a canting mast system on my F85SR.

So far this is a mental exercise because I've never even seen a canting system, let alone used one.

That being said, The thing I'm still struggling with is the mainsheet system.

My understanding is that when you can't the mast (say) 10 degrees to windward the traveller no longer works as expected. The traveller wants to move to windward, Resulting in all sorts of odd mainsheet responses.

I've thought of a number of ways to overcome this, but it's time to get advice from those who have actually used it.

Have at it guys.

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Jib sheeting will be out too Beatrix. You will have to come car aft and ease sheet to keep the same sheeting angle. I guess if you always use the same cant it will be easy to account for.

No idea about fixing the traveller though, obviously the sheet tension will stop you from being able to drop the trav in a gust.

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the traveller won't move to windward so things will be 'normal' until you try and dump the traveller in a gust and it won't budge until the mainsheet is let off.

This is why the MOD70 were falling over until they fitted a big red button to dump the mainsheet double quick

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Jethro, good point on the jib sheeting. I'm thinking that I'll drop the mast to leeward before the tack, (which will have the effect of letting the jib off) and then pulling it on again on the other side. That all sounds pretty safe.

Teamvmg,

Here is the idea I have been trying to develop, (note it is a concept and not fully thought through, hence the request for thoughts)

1) fix the upper mainsheet block to the boom as per usual.

2) fix lower mainsheet block to the top of a bridle 

3) the lower end of each side of the bridle is fixed to separate traveller cars, free to run on the traveller track

4) the port sde traveller car  is connected to the port side traveller control line and ditto for the starboard car.

5) in normal operation then there are two lines holding down the lower mainsheet block, one running at about 45 degrees to the windward traveller car, and one running down at 45 degrees to the Leeward traveller car.

6) when a puff hits the windward traveller car is released. It moves to Leeward, allowing the boom to both move to leeward, and rise and also move to leeward ( you may need to sketch the arrangement because I don't know how to add a sketch here.)

7) when the puff ends the windward traveller car is pulled back to windward, restoring the boom position and mainsheet tension.

The problems I perceive are:

a) limited scope to release sail ( so make bridle as long as possible) 

b) high traveller controlling loads to pull mainsheet tension back on through the windward traveller car. (Make traveller control line 4:1 or more)

What does the brains trust think?

 

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I have a canting rig on my 26' racing catamaran- Felix.  The canting mechanism is primarily setup to allow us to self right the boat if we get knocked over.... but we do use it from time to time for a performance boost if we are in more stable conditions.  Canting the rig is a very noticeable gain for us when flying a hull.... mostly the increased righting moment of moving the mast past the center of gravity when sailing in waves.  The mainsheet traveler has not been an issue for us-- but on our boat the helmsman has mainsheet in hand and is playing that to keep the hull skimming in those conditions.  With the square top main and 10:1 purchase this amounts to 3-12 inches of sheet play to depower the top of the sail or crank it back on to keep things moving.   So for us in an oh shit moment (big gust or header on a reach) -  our response usually starts in letting the mainsheet out and some helm response--- traveler is the third thing that gets eased --so never really notice it binding on the catamaran. 

Jib leads get adjusted to the conditions and hopefully left for a while.   Self tacking works as long as we cant the rig as we come through the tack.

 I do not like to let it cant the wrong way with a load as the shroud angles decrease which for us on a narrow catamaran can drastically increase the shroud loads... but for you on the F85 it wont be as much of an issue.

The other two boats up here in the Pacific Northwest with canting rigs would be better analogs for you.  One person to talk to would be Kim from the f31 Cheekee Monkey who use to sail with a canting rig when he was racing his tri.... or Duncan from the highly modified 8.5m tri Dragon who currently races with a canting rig.  I believe both of those boats use a hydraulic ram midship to cant the rig, shroud ends of thick spectra go through blocks to the center of the boat where the hydraulic ram is.  For Felix we use lines, a bunch of purchase, and a line driver/bi-directional winch to cant but our loads are a lot lower.

My vote would be to go for it, focus on a clean canting system, and worry about the rest once its back on the water.  

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That traveller set up sounds like a lot of effort. On the F85, i think that you get over the dig dump moments with good mainsheet control and co-ordination between mainsheet and traveller operatives. That traveller won't budge till the mainsheet is off!

If you have a crewman easing the fine trim of the mainsheet, the skipper can operate the traveller and also have the coarse trim of the mainsheet to hand if needed.

The danger is that, if you have too much purchase on the fine trim and not enough on the coarse trim - the loads are so much that the coarse trim can't be released. I think I ended up with a 9;1 mainsheet and a 4;1 fine trim which worked ok

NOTE!  - not a canting rig though! Just speculating!

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This year I have played a little with my setup and is working ok now after stripping some cover from the dyneema to run it easier thru the blocks.

http://f32thriller.blogspot.com/2018/12/canting-rig-option-setup.html

One thing I have to fix is my rotating sensor what had so little room for the magnet what was twisted of during canting of the mast.

This weekend give it another try after some adjustment of the magnet.

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1 hour ago, mowgli said:

This year I have played a little with my setup and is working ok now after stripping some cover from the dyneema to run it easier thru the blocks.

http://f32thriller.blogspot.com/2018/12/canting-rig-option-setup.html

One thing I have to fix is my rotating sensor what had so little room for the magnet what was twisted of during canting of the mast.

This weekend give it another try after some adjustment of the magnet.

Nice blog. 

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Thanks all,
It sounds like the simplest arrangement is to just lock the traveller and play the mainsheet.
Since that is the quickest and easiest to set up, I'll have a go with that.
 

So, while we are talking about canting rigs, How Much?
I've been assuming the target is to have the mast vertical when the hull is fully pressed (maximum float submersion)
But foiledagain raises a good point about rapidly increased shroud tension when the rig can't to leeward.( Which I hadn't considered)

Any other concerns?

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20 hours ago, SeaGul said:

Nice blog. 

Thanks, I am still exploring the possibilities what can be trimmed so many things (foils, canting rig, water ballast) 

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On 8/17/2021 at 3:08 AM, teamvmg said:

the traveller won't move to windward so things will be 'normal' until you try and dump the traveller in a gust and it won't budge until the mainsheet is let off.

This is why the MOD70 were falling over until they fitted a big red button to dump the mainsheet double quick

The Mod 70's had/have a hydraulic mainsheet. The original hoses connecting everything were found to be too small in diameter to allow for "instant" releasing They already had 'panic' release valves, but there's a lot of fluid that has to flow to allow cylinder to extend

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We don't use canting too much on our 31-1D when we are lake sailing, but we do cant the rig offshore....  I've never noticed any issues with the traveler, main sheet or jib...  Once we cant the rig and tack over we just trim the sails to the new tack and go...  Try it before you overthink it.

 

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21 hours ago, Beatrix said:

Thanks all,
It sounds like the simplest arrangement is to just lock the traveller and play the mainsheet.
Since that is the quickest and easiest to set up, I'll have a go with that.
 

So, while we are talking about canting rigs, How Much?
I've been assuming the target is to have the mast vertical when the hull is fully pressed (maximum float submersion)
But foiledagain raises a good point about rapidly increased shroud tension when the rig can't to leeward.( Which I hadn't considered)

Any other concerns?

about 7 to 8 degrees from what i've once read somewhere...

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Tilting the rig past vertical at maximum desired heel (say by 5 degrees) does make great sense aero wise.

Maintain your ambition!

The reasons for the small but effective amounts on the big multis were, in part:

1. The weight and ce of the rigs was quite high, so 10 degrees of cant achieved quite a bit, just in relation to the rig Frogc.g. movement

2. Hydraulic systems are not very efficient for long throws.

3. The sheeting complexity increases quite rapidly at larger cant angles.

 

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Too see the canting together with foils as mowgli seems to do is interesting;  the foil lifts the lee ama - so the boat is near level - then a canting rig will provide righting moment - and also add som lift from the sails. 

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2 hours ago, SeaGul said:

Too see the canting together with foils as mowgli seems to do is interesting;  the foil lifts the lee ama - so the boat is near level - then a canting rig will provide righting moment - and also add som lift from the sails. 

The rig is most efficient when vertical. Beyond that I would expect any benefits to come from additional righting moment as the vertical force will be tiny in relation to the weight of the boat. Also the efficiency decreases again past vertical.

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Interesting thoughts

My thinking was that I don't want the mast leaning to leeward which consequently means the sails are generating downward force which will drive the Leeward float deeper into the water. By keeping the mast vertical the Leeward float will be unloaded by some considerable amount. This in turn will allow more sail pressure for more performance

This will help upwind I believe, and will allow greater speed upwind

But downwind is where I have most concerns - pitch pole

Looking at water ballast to address this issue.

I'd love to fit C-foils but the costs are huge and I have other improvements that offer more bang for buck.

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We never cant the rig going downwind... only upwind or on a reach in light air.  We have c-foils also, which do start to lift the bows above 15-17 knots boat speed.  My feeling is that overall in the Pacific Northwest, the C-foils are not a net gain as we have mostly light winds.  But that they make the boat a lot more forgiving and thus add a safety factor.  We were in some terrible conditions (for a 650 lbs cat) in the 2017 R2AK race coming through Dixon entrance after a storm-- 25-30 knots wind on the quarter, 8-12 foot seas stacked up with an opposing tide.  As the boat would start to surf down a wave, I would brace myself for stuffing the bows (old reflexes from Hobie cats).  But the bows would lift and the boat would take off at speed without drama every time.  We could surf the wave until it petered out and pick the next face to do it again.   It turned a situation that could of been life or death into one of the most amazing sailing experiences of my life.  Made me want to sail the boat to Hawaii--- but I hadn't slept for 3 days at the time so maybe my judgment was a bit off.

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Ref windsurfers ; they can fly with the mast canted upwind. Also they change the centre og effort of the sail by canting it backwards - to have an adjustable forstay can give that effect on a bot too - canting and moving backwards should have good effects and be trim possibilities. 

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I am not sure a windsurfer is a good analogy. The cant the rig to windward to be able to get their bodyweight outwards which is their primary source of righting moment and probably sacrifice some aerodynamic efficiency for that.

However, what you can learn from a windsurfer is that canting and tilting also have a steering effect and need to be balanced, i.e. if they tilt their rig to windward the center of effort also moves to windward which they offset by tilting the sail aft to go in a straight line. Hence if you cant your rig to windward your boat will develop more lee helm unless you do the same.

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13 hours ago, neuronz said:

The rig is most efficient when vertical. Beyond that I would expect any benefits to come from additional righting moment as the vertical force will be tiny in relation to the weight of the boat. Also the efficiency decreases again past vertical.

Canting rig is only more efficient when there is enough breeze to lift the windward side .... there would be no gain in light air as said... The windsurfer analogy is a good one

13 hours ago, Beatrix said:

 

But downwind is where I have most concerns - pitch pole

Looking at water ballast to address this issue.

I'd love to fit C-foils but the costs are huge and I have other improvements that offer more bang for buck.

The idea is to only put a canting mast on performance multis used in anything more that light breeze and in those conditions the apparent wind is always forward due to speed unless almost dead down wind so no cant needed.

I too would love C foils but i'm guessing a $40k exercise for me

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Thanks PIL66, this boat goes straight to my question of how to set up the sheeting on a boat with a canting mast.

Time Machine has a hydraulic traveller control. So far so good.

But while that is interesting, hydraulics just makes it easier to do what can be done with block and tackles.

The mainsheet is on a winch, which allows the mainsheet to be pulled on very fast when there is no load on it, but then apply huge tension when needed. It can also be easily dumped in an emergency.

So the sheeting system sounds like the traveller is locked in one position and then the power is controlled by winching the mainsheet.

That sounds simple, safe and effective, but at the expense of losing the traveller effect. By which I mean that when eased, the boom  moves horizontally in a puff, the leach stays tight and the sail shape stays constant.

By easing the mainsheet the boom rises vertically, the leach lays off, the mast straightens, filling the sail and the top of the sail is released.

Is this important? Are our masts so stiff that the mainsail doesn't get Fuller when the mainsheet is eased?

 

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7 minutes ago, Beatrix said:

By easing the mainsheet the boom rises vertically, the leach lays off, the mast straightens, filling the sail and the top of the sail is released.

Invest in a really heavy duty vang and boom.  

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9 hours ago, PIL66 - XL2 said:

Canting rig is only more efficient when there is enough breeze to lift the windward side .... there would be no gain in light air as said... The windsurfer analogy is a good one

The idea is to only put a canting mast on performance multis used in anything more that light breeze and in those conditions the apparent wind is always forward due to speed unless almost dead down wind so no cant needed.

I too would love C foils but i'm guessing a $40k exercise for me

For light winds - its less weight more sail that is the thing and also trimming the balance. But in breezy the many options can be played with. The cantig rig - and adjustable forstay is rather easy and cheap things to do compare to foiling/lifting options.  T-foil rudders is cheaper than foils.

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