Tuning question--a puzzle to the sail maker.

[Frank Langer]

The rig tuning guide for the 1984 E30+ suggests that there should be no mast rake or even much mast bend in the mast on the E30+. I have tuned it according to the suggestions (the guide is on this site under the downloads for the E30+), and the boat sails well in most conditions--rounds up a little when I let go of the wheel, rudder turned only slightly (about a 1/4 turn on the wheel, which I think turns the rudder less than 5 degrees) to keep her on course in 10 - 20 knot winds, and she holds her course nicely with just the wheel brake on if I set her up right.

However, I recently began talking with some sail makers about new sails, and they were each quite puzzled when I described that the mast was quite straight up without mast rake or mast bend. They think this is very unusual, especially for a fractional rig sailboat.

Can anyone explain why the E30+ is intended to be tuned with the mast straight (or have I misunderstood something in the tuning guide?). Are other E30+ owners tuning their rig differently--if so, with what results?

While I am very happy with how our boat sails, I am always trying to increase my knowledge and tweaking things on the boat to make her sail even better.

Thanks,
Frank

 

[Seth]

Hey Frank!

The reason you are seeing that language is not from any deep wisdom for optimizing performance..it is becuase the market for this boat was primarily cruisers who would not have backstay adjusters.

In fact, setting the rig up with a little prebend and using the backstay adjuster to shape the mainsail and play with headstay tension will only improve performance. Ignore the tuning guide for your purposes!

As for rake, the right setting will vary depending on how the boat is loaded (heavy/light and fore/aft) and whether or not you use crew on the rail for stability. If you like the way it sails for the way you use it it is probabaly fine.

Happy new year!

S

 

[Frank Langer]

Thanks, Seth! I appreciate your knowledgable advice on this. I will play with the tuning a bit to see if I can optimize it with some more mast rake and mast bend. It's already a fairly fast, responsive boat, but if I can enhance her performance, so much the better!

Thanks again!

Frank

 

[Seth]

Anytime Frank

..but you already knew that!

The only reason to add more prebend is if you are not able to get the mainsail board flat with the backstay and outhaul maxed. If this is the case, it means your mainsail has more luff curve than the mast has bend ability, and as such you are not able to remove all of the luff curve (read:draft) when you get to max bend.

Ideally, you want the main to go from full depth with zero backstay to very flat by the time you reach 80-90% of available bend.

Can you refresh me on the shroud configuration? If I recall, the 30+ does not have aft lowers, but does have fwd lowers (or is it the other way around?)..Or, does it have neither and the lowers are inline with the uppers and intermediates? I know it is different than most other eboats, but I can't recall how it is set up..

Refresh me on this and I give some more help.

Thanks!

 

[Frank Langer]

Thanks, Seth.

I would like to be able to flatten the mainsail more. Unfortunately, I'm a bit limited by the current standing rigging--I have loosened the toggle on the furler/headstay to make it as long as possible to promote mast rake. I can't get the top of the mast to bend back because the adjustable back stay is a bit too long, so it's hard to get enough tension in it to bend the mast back noticeably. I can tension it enough to flatten the sail a bit when overpowered. Unless you have a better idea, I may have to hire a rigger to shorten the backstay to get the bend I might want.

The lower shrouds on the E30+ are very slightly aft of the upper and intermediate shrouds, but not as far aft as on many fractional rigs I've seen. I have tried loosening them, thinking that if they are angled back even slightly they will inhibit mast bend if they're too snug, but that didn't make any appreciable difference. The double spreaders are perpendicular to the mast, not angled back as on some other boats.

At this point I have the uppers tensioned at between 12 - 15% (not the 20% that some books recommend), the intermediates a bit less and the lowers also at about 12%. None of the shrouds look or feel loose when sailing close hauled in 15 - 18 knots wind and toe rail a few inches above the water (I'm guessing about 20 degrees heel); the leeward shrouds feel slightly less taut than the windward shrouds but they do not look at all loose. The mast stays straight and does not bend off to leeward. I think I have the shrouds tensioned fairly correctly, though I'm always open to suggestions for improvement.

The boat sails quite well, rounding up slowly in 15 knot winds with no noticeable lee helm in any conditions. In 15 knot winds I have the wheel turned about a quarter turn which looks like it turns the rudder about 5 degrees or less to hold a straight course (the wheel turns two full turns from side to side). I feel slight, but not strong, pressure on the wheel. I can apply the wheel brake and it will hold it's course in this manner for quite a while. I regularly achieve 6.5 knots in 15 knot winds (always a bit faster on port tack than starboard for some reason), and have seen 7.2 knots in good wind/low wave conditions. My Hood mainsail is 10 years old, my 125% furling headsail is 8 years old, both still in reasonable shape though I know I'm on borrowed time for optimal performance.

Any further suggestions? I really appreciate your advice!!

Frank

 

[Seth]

Tuning

Nice description.

OK, since you have no fwd lowersto tighten we can forget that. I would ease up on the aft lowers as much as you can and still keep the mast in column. From there, I agree, you need to shorten the backstay so you can get some real tension on the adjuster. You should eventually be able to see 4-6" of bend. If the main does not blade out at this point it may be too full, but the first thing is to get some bend going...

 

[Frank Langer]

Thanks, Seth. I'll try that.

Frank

 

[sailorman37]

30+ mast rake

Frank,

I too have the 30+, but haven't sailed it much since I spent the last few years redoing the boat. I too notice at rest in calm water with no crew on the boat that the mast is pretty much vertical.

However, I was able to get the boat out for an afternoon sail a few weeks ago and it seemed to have slight weather helm. Does rake just move the center of effort to the rear and increase weather helm? Does rake add anything to speed?

With the shroud setup almost perpendicular to the mast, it sounds like bending the mast to flatten the sail will introduce some more rake?

Any thoughts?

 

[Seth]

Rake vs bend

There are numerous posts on this topic, but to summarize, raking the mast aft does indeed move the CE aft in relation to the CG so it WILL induce more weather helm.

All things being equal, you want a slight amount of weather helm when sailing close hauled in anything over about 6-8 knots of breeze- such that if you let go of the wheel, the boat will very slowly head up into the breeze. if it snaps up right away, or if you are always having to carry 1/4 turn or more to keep the boat going straight, you have too much.

Weather helm does not make the boat any faster, but it DOES help the boat point a bit higher. Excessive weather helm just causes rudder drag to keep the boat going in a straight line, and this rudder drag (angle) will slow you down on all points of sail.

Other things can cause weather helm: too much weight forward and leeward heel are the big ones.

The simple way to determine proper rake is to go out sailing and trim the boat for close hauled sailing with sails properly trimmed, jib leads correct, etc.in about 5-10 knots of breeze. Make sure you have good fore and aft weight balance (don't stash everything in the bow area). Get in a good groove and let go of the wheel (pedestal brake off!). The wheel should be about centered or very slightly turned down (no more than 1/8 of a turn). The boat should slowly head up so that the genoa starts to luff.
If so, you are about right. If the boat snaps up into the breeze (and/or you are carrying 1/4 turn or more in the wheel) you may have too much aft rake. If the boat wants to bear away you have too little rake and should drop it back. Ideal scenario is either very little or no helm in light air, and a small amount (as described above) as you get to 8-10 knots TWS close hauled. In breezier conditions as the boat heels, some weather helm is inevitable, but if you are always fighting it (and you are not overtrimming the mainsail), you likely have too much aft rake. I have made some suggestions previously on this site for a base setting from which you can adjust to fit your taste and fore and aft loading.

As to your question about bend, this does NOT affect rake- it only changes the draft of the sail..more bend shoves the middle of the mast forward and flattens the sail, less bend straightens the mast and increases sail depth. It CAN affect weather helm since an overpowered boat with too deep of a sail will heel more, which creates more helm, and a flatter sail makes for a flatter boat which heels less, and will have less weather helm..

Hope this helps,

S

 

[sailorman37]

Seth,

Thank you very much, that was helpful. Hopefully I'll get out this week and tune it as you suggest.

Brad

 

[Seth]

30+ Tuning

Sure-let us know how it goes

 

[Frank Langer]

Hi Brad,
I have been out sailing for the past week, so sorry for my tardy reply. Seth's reply above is dead on--he is the guru on this stuff. I have carefully tuned the rigging on our 1984 E30+, and I have no real mast rake, some mast bend. The shrouds are tensioned with most tension on the cap shroud, then the lowers and least on the intermediate. Cap shrouds are tensioned at about 12%. None of the leeward shrouds hang loose when close hauled in about 15 knots of wind, but they do feel a bit less taut than the windward shrouds; the mast stays straight and does not bend off to leeward.

With this tuning, the boat will readily reach speeds of 6.8 to 7.2 knots in 15 knots of wind if the hull bottom is clean and I have everything set up right. She always goes a bit fast on port tack than on starboard, and I have no idea why that is. My max speed when not surfing on larger waves is 8.2 knots, but that's in a good breeze with no real waves, ie. a relatively rare occurrence. Normal sailing is more like 6.5 to 7.2 knots. I think hull speed according to the formula is about 6.7 knots, so I think I'm probably doing ok.

Let me know how your tuning works out, and if you have any further suggestions, I would welcome them.

Frank

 

[sailorman37]

Frank,

I am going out sailing tomorrow so I will see how my tuning goes. To what are you referring when you say the cap shrouds are 12%. Is that 12% of the breaking strength or some other number?

Brad

 

[Christian Williams]

Do you have a cunningham? After tuning and bending, they work pretty well moving the center of an older mainsail. And at least it gives you something to do....

 

[Frank Langer]

Hi Brad,

Yes, 12% of the breaking strength. Some would say that's on the light side, that it can be at 15% or even 20%, but I'm not comfortable with them that tight. I think it's good if they begin to feel slightly slack on the leeward side when close hauled in 15 - 18 knots of wind, about 20 degrees heel, without looking at all slack. Others may have suggestions as well.

Frank

 

[Seth]

Rig tension

Hi Brad,

Yes, 12% of the breaking strength. Some would say that's on the light side, that it can be at 15% or even 20%, but I'm not comfortable with them that tight. I think it's good if they begin to feel slightly slack on the leeward side when close hauled in 15 - 18 knots of wind, about 20 degrees heel, without looking at all slack. Others may have suggestions as well.

Frank

The best way to get repeatable numbers is to use a LOOS gauge once you have it tuned, note the numbers, and use those as a reference. If you are interested in best performance, use this as a base and put a few turns (2 on caps, 1 on lowers and .5 on intermediates) on the rig for breezy stuff and back off a few for very light stuff- this will make the headstay sag and mainsail shape ideal for the extremes of wind conditions

 

[Frank Langer]

Hi Seth,

Thanks for this additional suggestion. On our boat the turnbuckles are held in place by a cotter pin, both top and bottom. It would be quite a lot of effort to remove them all, make the adjustment and then reinsert the cotter pin to adjust to varying conditions. So my question is, how critical is it to have the cotter pin in place while sailing? Do the turnbuckles actually move while underway, making it a risk that they come undone completely? Or can I dispense with them altogether?

Also, if I do need to keep the cotter pins, do you recommend taping them as one sees so often, or is it best to leave them uncovered to minimize water retention and corrosion?

Thanks,
Frank

 

[Seth]

cotter pins

The cotter pins must be in place when sailing-the leeside turnbuckles can unwind when not loaded. Havings said that, it should be fine to tape them over during the sailing season-just take it off for the winter (or change the tape twice a year if you leave the boat in year round). If you like, west marine sells cotter pins which are attached to velcro straps which make pulling the pins very easy and the velcro serves as a chafe guard when they are in place. Hope this helps!

 

[Seth]

The cotter pins must be in place when sailing-the leeside turnbuckles can unwind when not loaded. Havings said that, it should be fine to tape them over during the sailing season-just take it off for the winter (or change the tape twice a year if you leave the boat in year round). If you like, west marine sells cotter pins which are attached to velcro straps which make pulling the pins very easy and the velcro serves as a chafe guard when they are in place. Hope this helps!

Here is a pic- they are available via several suppliers:

 

[Frank Langer]

Thanks, Seth, for taking the time to send the additional information. They look very cool! I had never seen them before, but I can see how they would make cotter pin removal quite easy, and also provide padding to minimize small cuts or abrasion that cotter pins can cause. I'll look for them at our chandlery.

Frank