Too much mast rake

[sirius86]

Second season on a Sirius 21 and I'm trying to get it better dialed-in this year now that we've learned the basics.

Problem is we have way too much mast rake which is causing a lot of weather helm. I re-tuned the rig this year using a proper tension guage (and with the help of someone more experienced than myself!). The forestay is "properly" tensioned to about 15% stretch and even with the rearstay at half of that tension I still have way too much rake.

Are there standard tension recommendations for this boat (with original main/jib)?

The owner's manual calls for about 6" of rake as measured with the main halyard at the boom and I have more like twice that amount!! I raised the mast twice to make sure that nothing was wedged underneath the mount.

I also noticed that the stern of the boat sits a little lower than the bow (motor is probably bigger/heavier than originally designed for) so I'm guessing this is just further adding to the weather helm. The boat rounds up very harshly in a gust!

I'm not sure what else I can do... Any ideas? Thanks!

 

[jksirius]

In my limited experience I have found that the mast is quite flexible. Do you have a baby stay? I do, and it has a great impact on mast bend.

I control rake by forestay length and forestay tension by tensioning the backstay. I've never measured tension with a gauge, but, as described in Sail and Rig Tuning by Ivan Dedekam, I tune so that forestay tension is such that there is no sag at about 15 knots close-hauled, maybe a bit less because it's a small boat.

I'll do the halyard test on Sunday if I don't forget, but I have a fair bit of rake and bend and don't go uncontrollably to weather unless the boat is heeled more than 30-35° and there is a sustained gust of at least 15 knots. By then I should have reefed the main. Over 35° I'm guaranteed the boat will round up and there is nothing I can do about it - which is actually nice because it's near impossible to get wet.

I do let out a lot of main when needed to keep her on her feet and when the gust is strong I pinch (or feather or whatever else it's called).

 

[MikeHoncho]

What ever you start with rake wise, you will end with it if tuned evenly. Loosen everything up and dial in the right rake then tune the rig evenly. How much is recommended?

 

[sirius86]

First one point I don't understand, if the engine is heavier, why is the stern higher?

Now in my limited experience I have found that the mast is quite flexible. Do you have a baby stay? I do, and it has a great impact on mast bend.

I control rake by forestay length and forestay tension by tensioning the backstay. I've never measured tension with a gauge, but, as described in Sail and Rig Tuning by Ivan Dedekam, I tune so that forestay tension is such that there is no sag at about 15 knots close-hauled, maybe a bit less because it's a small boat.

I'll do the halyard test on Sunday if I don't forget, but I have a fair bit of rake and bend and don't go uncontrollably to weather unless the boat is heeled more than 30-35° and there is a sustained gust of at least 15 knots. By then I should have reefed the main. Over 35° I'm guaranteed the boat will round up and there is nothing I can do about it - which is actually nice because it's near impossible to get wet.

I do let out a lot of main when needed to keep her on her feet and when the gust is strong I pinch (or feather or whatever else it's called).

Meant to say the stern sits LOWER - good catch! I will edit the original description.

How you describe setting it up is similar to what I did. Started with everything loose and went from there. With everything detensioned the mast swept back with a strong rake before even tightening anything. Makes me wonder if there is just something wonky with the foot of the mast to begin with (I'm not sure what that connection point is called...).

The mast is not *bent* (in a damaged way), though I have put a very slight forward curve into it using tension on the baby stay. This didn't change the rake any unfortunately. I'm still very much learning..!

I'll see if I can get a side profile pic tomorrow.

In moderate winds it sails fine albeit with a bit more effort at the helm. Where I've got caught a few times is on a close haul/reach where sudden strong gusts heeled me over so far and fast that I broached (as best as I understand anyways!) before being able to let out the main or adjust course. This has happened even with a reefed main. Flying into a tack unexpectedly with the rails in the water is scary!

This could very well be a piloting error of mine! I'm guessing it has at least something to do with strong weather helm though...

Thanks for your input!

 

[sirius86]

What ever you start with rake wise, you will end with it if tuned evenly. Loosen everything up and dial in the right rake then tune the rig evenly. How much is recommended?

6" of rake as measured at the boom using the main halyard as a plumb is what's suggested in the original owner's manual as a starting point, with tweaks then made to adjust weather helm. In my case I'm way off: closer to 10"!

One thing that is not clear on the manual though is which tail of the halyard to use as the plumb, but this would change the reading by only ~1": the diameter of the block that it rounds at the top of the mast.

The problem is I can't seem to get the excessive rake out of the mast even when starting with everything loose. As mentioned earlier the forestay was already made to be twice as tight as the rear and it's STILL leaning back..! I'm not sure how far I should push it.

Thanks for the reply!

 

[MikeHoncho]

Is the forestay a furler? If so it may have been replaced to accommodate it and made too long. What does the cabin look like around the mast? Remove the main sail and pull the halyard tight making it parallel to the mainsail track and measure the distance, add 6” to it then adjust the rack to the sum. You’re not building a piano, it doesn’t have to be perfect..
I’ve used the “measure and stretch” method for tuning and it works but is time consuming and tedious. I use a Loos gauge and it’s worth the money. Gives you consistent and repeated tensions. It sucks spending hours with the measure method then take it out and tighten them up anyways when the rig is loaded.

 

[sirius86]

Is the forestay a furler? If so it may have been replaced to accommodate it and made too long. What does the cabin look like around the mast?

Hank-on jib so original forestay I'm guessing. Around the mast the deck/cabin/post are all firm and look normal as best I can tell too.

I'm not quite sure I understand your stretch and measure method...

I have access to a loos tuning guage that I used for the initial setup. What tensions do you use for your Sirius (knowing that it would be a bit different from boat to boat, but that could give me a good starting point). Thanks again!

 

[jksirius]

Meant to say the stern sits LOWER - good catch! I will edit the original description.

How you describe setting it up is similar to what I did. Started with everything loose and went from there. With everything detensioned the mast swept back with a strong rake before even tightening anything. Makes me wonder if there is just something wonky with the foot of the mast to begin with (I'm not sure what that connection point is called...).

The mast is not *bent* (in a damaged way), though I have put a very slight forward curve into it using tension on the baby stay. This didn't change the rake any unfortunately. I'm still very much learning..!

I'll see if I can get a side profile pic tomorrow.

In moderate winds it sails fine albeit with a bit more effort at the helm. Where I've got caught a few times is on a close haul/reach where sudden strong gusts heeled me over so far and fast that I broached (as best as I understand anyways!) before being able to let out the main or adjust course. This has happened even with a reefed main. Flying into a tack unexpectedly with the rails in the water is scary!

This could very well be a piloting error of mine! I'm guessing it has at least something to do with strong weather helm though...

Thanks for your input!

You said your mast is raked even when everything is loose. I'm not sure I understand as when everything is loose - both back and fore stays - the mast can then be pushed to rake forward or back. In other words, if everything is loose, there should be nothing stopping it from being straight. Perhaps the butt-end of the mast or the plate are somehow angled, but IMO even if it were resting on the front corner of the butt on the plate it should be possible to have it straight, and then regulate how much rake there is by the length of the forestay.

When I refer to bend, I'm not talking about damaging, unnatural bend, but about mast bend as another tool - i.e., rake, bend, stay tension, etc. Mast bend also contributes to whether helm.

My main point is that I have quite a bit of both rake and bend, and there is a lot of weather helm in gusts. In my first summer with the Sirius it happened quite often that a gust would suddenly bring me to weather, even make me unexpectedly tack. It was frightening and tough to deal with single-handed. Now I've learned that, at least for me, the weather helm is correlated a lot with heel and that I don't want more than 20 degrees heel or I'm fighting the tiller. Thus, the key for me is hand on the mainsheet ready to increase twist and spill wind to keep her on her feet. This manages weather helm, even with my bend and rake, quite nicely until it's time to reef.

I know you want more info on tension and the others have much more data and experience with that - I'm just putting in my two cents for dealing with weather helm while sailing as I have a suspicion that even if you get your mast rod-straight, you'll still have weather helm in gusts that will have to be dealt with by sailing technique.

Please keep us posted about how rake affects helm though, I'd like to know how you've fared.

 

[Will Gilmore]

I've not tuned a masthead rig before, but the ideas should be the same here.

As Mike wrote, set the rake with the forestay first. The halyard end to measure is the end you attach to the peak of your sail.

Set your baby stay to match.

This is done by eye and you will have the backstay just tight enough to hold the mast against the forestay for setting the rake, not sagging loosely.

Your baby stay will then be tightened just enough to slightly move the mast forward, barely relaxing the forestay. This is just to test the baby stay tension. Relax the baby stay just enough to return the mast to position.

Then, tighten the backstay. You should leave the halyard hanging, with a weight on it, just over the gooseneck of the boom and watch your rake. Pause and sight up the mast. At first, you will probably see a little more rake as you tighten. You can stop and take the rake back out if it looks too much.

Tighten the backstay just until you see the baby stay start to put a bend in the mast. Then, back of until straight. Put the desired bend back in with your baby stay.

I wonder how old your sails and your stays are. Older sails give more weather helm.

-Will

 

[Joe]

Adjusting tension on the forestay and backstay is not the way to change "rake". Rake is controlled by length of the fore stay....while tension is reserved for sail trim options.
Therefore, you should be fiddling with the forestay's pin adjuster or turnbuckle at the stem head. Like wise for the backstay, although most serious sailors will have a mechanism to change backstay tension depending on the desired sail trim conditions. On masthead rigs, like the Sirius 21, backstay tension will affect the forestay sag (tension) rather than bending the mast like it does on a fractional rig.

To measure rake, you can add a small weight to the main halyard or hoist a weighted plumb line for a more sensitive measurement. The shackle end of the line would be the best for this measurement since it exits at the top of the mainsail track. Use the top of the boom to measure the intervals, if that's what the manual instructs.... but heck, it doesn't really make any difference, since any changes are only related to your boat and its performance.

Anyway, to reduce rake (making the mast more perpendicular) shorten the forestay. If you're backstay just has a turnbuckle, you'll want to give it a little more length too. The tension should be moderate, but there's no tuning spec (that I know of) for the forestay and backstay... As you become more experienced, you'll want to be able to adjust backstay tension while sailing.... up wind generally more tension, which will help flatten the sail and make the halyard more effective in controlling draft position. Down wind, you'll want to ease the backstay to give the forestay some sag which will allow for a fuller headsail. Good luck, have fun.

 

[shemandr]

When you tuned the mast, where in the range of the forestay turnbuckle (If you have one) were the threaded studs. Was there a short stud or were the studs almost meeting in the middle? Once the forestay wire is cut, by whoever made that forestay, the only way to adjust the forestay length is tightening the turnbuckle. There's maybe 6 inches of adjustability there. So if the turnbuckle is a short as it can be (Studs nearly touching) you're at the end of adjustability and you have to go to other options. Replacing the forestay is the most obvious option. Before you do that fairly drastic action you should look at your sails, running rigging and sailing style. Stretch in either can contribute to weather helm as the wind pipes up. As for your sailing style, all boats will want to round up if allowed to heel excessively - similar to how a ski turns if on its edges. So maybe you need to control weather helm with release of the traveler, if you have one, or mainsheet, flattening the sails and earlier reefing.

 

[sirius86]

Wow what amazing info to wake up to! Thank you everyone for taking so much time in helping me out.

My main point is that I have quite a bit of both rake and bend, and there is a lot of weather helm in gusts. In my first summer with the Sirius it happened quite often that a gust would suddenly bring me to weather, even make me unexpectedly tack. It was frightening and tough to deal with single-handed. Now I've learned that, at least for me, the weather helm is correlated a lot with heel and that I don't want more than 20 degrees heel or I'm fighting the tiller. Thus, the key for me is hand on the mainsheet ready to increase twist and spill wind to keep her on her feet.

This is so spot on for me too. Past 20 degrees of heel and I'm fighting to keep it in a straight line. I sail on a lake that is notorious for unpredictable gusts and do a lot of solo sailing as well, so my hand definitely lives on the main sheet like you're saying too. A sudden round-up is definitely scary!

I will try to readjust the rigging again using all of the methods listed above to see if that helps, otherwise it sounds like I may just need to learn to better work around it. I have only one year's sailing under my belt so there is definitely still so much to learn.

I've been working to really improve my sail trim this year (finally got tell tales and a wind vane which help so much) and it's made a huge difference in terms of speed. So learning to deal with too much speed and heel is this year's project I guess haha.

 

[jssailem]

Learning to sail your boat rather than reacting to your boat is the adventure.

When you are ready a study of what is actually happening when the wind fills your sails is in order.

Gentry Sailing | Theory and Practice

A lot of discussion in this link... Sail Trim and Aeronautic Theories.

Be careful. As you go faster you will want to continue to improve. You will soon learn that the next step is new sails.

 

[sirius86]

When you tuned the mast, where in the range of the forestay turnbuckle (If you have one) were the threaded studs. Was there a short stud or were the studs almost meeting in the middle? Once the forestay wire is cut, by whoever made that forestay, the only way to adjust the forestay length is tightening the turnbuckle. There's maybe 6 inches of adjustability there. So if the turnbuckle is a short as it can be (Studs nearly touching) you're at the end of adjustability and you have to go to other options. Replacing the forestay is the most obvious option. Before you do that fairly drastic action you should look at your sails, running rigging and sailing style. Stretch in either can contribute to weather helm as the wind pipes up. As for your sailing style, all boats will want to round up if allowed to heel excessively - similar to how a ski turns if on its edges. So maybe you need to control weather helm with release of the traveler, if you have one, or mainsheet, flattening the sails and earlier reefing.

I paid a bit more attention while out today and noticed that on a close haul the forestay begins to sag, I'm guessing as a result of having left my rearstay looser. I'm guessing this would have the same effect as old tired and stretched out rigging and catch more air (nice on the calm days I guess!).

I haven't done a reset yet but the more I read the more it looks like I need to go back to square one with the tuning.

Thanks again everyone for the help.

 

[sirius86]

Learning to sail your boat rather than reacting to your boat is the adventure.

When you are ready a study of what is actually happening when the wind fills your sails is in order.

Gentry Sailing | Theory and Practice

A lot of discussion in this link... Sail Trim and Aeronautic Theories.

Be careful. As you go faster you will want to continue to improve. You will soon learn that the next step is new sails.

Thank you for the links - I'll be sure to give them a read.

I've definitely been on a deep-dive into sail trim and aerodynamics over the past month though at first it was quite difficult to separate the advanced trim for racing with a crew to the more practical "a few things you need to do while cruising single-handed" style advice. Lots to learn from both approaches and of course seeing is believing

Cheers

 

[shemandr]

I agree that too many sail trim guides go too far with the theory side. Once the vectors come out - large numbers of readers drop out. That's not to say, sources such as Gentry's writings aren't useful. But sometimes individuals need an "If this happens, do this" approach.
As for your forestay sag, that can be lessoned with backstay tension. Even on masthead boats. As Joe said in post #10, many sailors have an adjustable backstay. It's a great sail trim adjustment that I recommend. Not just for racing. When your boat sails well, properly trimmed it's much more enjoyable, safer and satisfying in terns of mastering the control of the boat (Not that it's ever mastered).
When a gust hits and the forestay sags, the jib becomes more full and more powerful just when you don't want it. When the forestay is too tight light air performance suffers. Set the rake with the forestay length. Set the forestay tension with the backstay.

 

[sirius86]

When a gust hits and the forestay sags, the jib becomes more full and more powerful just when you don't want it. When the forestay is too tight light air performance suffers. Set the rake with the forestay length. Set the forestay tension with the backstay.

It all makes so much sense now... I am going to do this asap - thank you!!

 

[Will Gilmore]

I paid a bit more attention while out today and noticed that on a close haul the forestay begins to sag, I'm guessing as a result of having left my rearstay looser. I'm guessing this would have the same effect as old tired and stretched out rigging and catch more air (nice on the calm days I guess!).

You are right about the effects, but the reason may not be what you think.

When close hauled, your sheet should be taking a lot of, if not most of, the tension that's on the forestay. If you are seeing excessive sag in your forestay, you may be seeing a tired forestay, but also reverse bending in your mast. Since your boat is a masthead rig, greater pressure on the headsail won't increase the bend of the mast that can result in flatter mainsails like a fractional rig will see. Instead, it can cause a reverse bend because the entire luff of the mainsail is trying to pull back on the mast through the boom and and the sheet. Move the traveler block to midship and vang the boom. You should be able to take nearly all the tension off the backstay. What's probably happening is your mast is compressing by bowing backwards. Make sure you have a good visible bend in the mast from the tension on your baby stay and your shrouds are set correctly, no falling over turnbuckles on the lee side when reaching. Your lower shrouds are responsible for keeping the mast straight while the upper shrouds prevent the mast head from moving out of column.

Check the shape of your mast as well as the tension on your stays.

-Will

 

[jssailem]

a few things you need to do while cruising single-handed

There is a great "Free" guide to solo sailing which may provide ideas to help you. Solo sailing is a great experience. Sailing with a crew is also a great experience. Heck Sailing is self is where it is at.

 

[sirius86]

You are right about the effects, but the reason may not be what you think.

When close hauled, your sheet should be taking a lot of, if not most of, the tension that's on the forestay. If you are seeing excessive sag in your forestay, you may be seeing a tired forestay, but also reverse bending in your mast. Since your boat is a masthead rig, greater pressure on the headsail won't increase the bend of the mast that can result in flatter mainsails like a fractional rig will see. Instead, it can cause a reverse bend because the entire luff of the mainsail is trying to pull back on the mast through the boom and and the sheet. Move the traveler block to midship and vang the boom. You should be able to take nearly all the tension off the backstay. What's probably happening is your mast is compressing by bowing backwards. Make sure you have a good visible bend in the mast from the tension on your baby stay and your shrouds are set correctly, no falling over turnbuckles on the lee side when reaching. Your lower shrouds are responsible for keeping the mast straight while the upper shrouds prevent the mast head from moving out of column.

Check the shape of your mast as well as the tension on your stays.

-Will

Thanks for the fantastic tips! The ever-shifting interaction between rig/trim/sail/handling is enough to make one's head explode!

If I'm understanding your description correctly, a tight mainsheet and boom vang should essentially take all of the load off the rearstay when the boom's pulled in tight to centre-line during a closehaul...? In my case I was sheeted in tightly on the main when I noticed the otherwise tight forestay begin to sag during puffs and had the vang on too. I previously thought that the vang had more to do with controlling boom height while reaching downwind when there is more mainsheet out... So much to learn!

I do have a so slight mast pre-bend set in with the baby stay but I could try putting in more. One thing I am certain of is the shrouds: they're all holding the mast nicely vertical with good tension while under sail. I'll have to try to start paying more attention to the rigging while actually underway I guess.

One quick question before I try to retackle the rig tuning: to readjust the rake do I first need to de-tension EVERYTHING (including all of the shrouds) as well? Also, should it be rigged with the added weight of the boom/mainsail/topping lift attached? I'm assuming so, but want to be sure to do it right.

Thanks again