Captain Crunch
Member II
What should the mast rake be on my E 35-2? I believe it is measured by plumb bobbing down from the top of the mast to the deck and measuring from the base of the mast to the plumb bob.
Mast Rake E 35-2
- Thread starter Captain Crunch
- Start date
Mike.Gritten
Member III
IIRC, there is NO mast rake on the E35. Check the manual and specs in the documents section on this site.
I'm not sure if the E35 _2 was designed or not to have rake in the mast but it certainly benefits from a little. I did the plumb bob thing on my boat and measured out zero inches, 1in,2in, 3in, 4 inch and five inches using my hydraulic backstay to rake the mast. I have these measurements on an old batten taped to my backstay adjuster. Depending on wind I increase or decrease the rake from zero to five inches. It has a significant effect on the boat's upwind and downwind performance. If you don't have a backstay adjuster ( I didn't until last summer) I would set the mast back about 1.5" back using the plumb bob. This will give you better performance upwind without too much weather helm. If it's set to zero I find the boat has too much lee helm. Don't set it over 3 inches. The boat only needs that much rake when pointing high into a big wind.
Cheers
Michael
Impromptu E35-2 1970
#110
Cheers
Michael
Impromptu E35-2 1970
#110
Mast rake
I would agree a small amount of rake is a good thing for the 35-2-between 1.5-2.5" is where I would start, but I have sailed on a number of them with 6" or more.....it depends on how much breeze you normally sail in, and how much you want to favor upwind ability vs. reaching and running performance.. A good way to tell if the boat is well balanced is to go sailing, using the right sized headsail for the conditions, but stay betwen about 7-15 knots TWS (doing this test in over about 15 knots TWS adds too many variables). This means a 150%(ish) sized headsail if under about 10, and a 130 (ish) if comfortably above 10. If you only have a 130% genoa, do this test in at least 10 knots of TWS...
Sail upwind-making sure you have the genoa trimmed correctly with the leads in the right spot, and the mainsail correctly trimmed-nothing more than a small bubble (if any) in the luff, and all leech telltales streaming (top one can be stalled about 50% of the time). Assuming you do not have unusual amounts of weight in either end of the boat, from a solid close hauled course (and with the boat up to speed), let go of the wheel/tiller (if a wheel be sure the brake is off)...The boat should slowly head up into the breeze. If it goes dead straight, or bears away from the wind, you should add a little more aft rake. If it snaps up suddenly into the wind, you may have too much aft rake (but first double check your main was not overtrimmed!).
Michael-FWIW-your backstay adjuster is not intended to increase mast rake-it is intended to do 2 things: induce (or reduce) mast BEND to optimize mainsail depth, and reduce (or increase) headstay sag. Mast Rake, unlike bend, does not impact sail shape (okay, it can affect genoa clew height), it changes the balance of the sailplan vs. CG of the boat.
What you are seeing when you apply backstay seems similar to rake because the 35-2 mast is so stiff and does not bend much, and you are seeing the top of the rig move aft.. but the best way to do this with the 35-2 rig (if equipped with an adjuster) is to measure the rake with a SLIGHT amount of backstay tension-whatever you would leave on while at the dock. If you want more rake- EASE the HEADSTAY off in 1/2" increments, and measure with the bob. If you do not see any movement, then take up the exact same amount on the backstay, and re-measure.. When you arrive at the desired rake for your next test sail, pin the headstay. Now, when you are under sail you will have the desired rake, and you can use the backstay adjuster to fine tune the headstay sag, and flatten the mainsail with bend-as needed. You will find the mast bends much better with the aft lowers quite loose-as they normally should be..
The rule of thumb is to use headstay length as the determinant for rake. If you do not have a BS adjuster, then when you are adjusting rake with the headstay, be sure you ease or take up on the backstay the same amount when you are done (if you eased the headstay an inch, take up on the BS an inch, etc.). This way the relative rig tune should not change with the change in rake...
Enjoy!
S:nerd:
I would agree a small amount of rake is a good thing for the 35-2-between 1.5-2.5" is where I would start, but I have sailed on a number of them with 6" or more.....it depends on how much breeze you normally sail in, and how much you want to favor upwind ability vs. reaching and running performance.. A good way to tell if the boat is well balanced is to go sailing, using the right sized headsail for the conditions, but stay betwen about 7-15 knots TWS (doing this test in over about 15 knots TWS adds too many variables). This means a 150%(ish) sized headsail if under about 10, and a 130 (ish) if comfortably above 10. If you only have a 130% genoa, do this test in at least 10 knots of TWS...
Sail upwind-making sure you have the genoa trimmed correctly with the leads in the right spot, and the mainsail correctly trimmed-nothing more than a small bubble (if any) in the luff, and all leech telltales streaming (top one can be stalled about 50% of the time). Assuming you do not have unusual amounts of weight in either end of the boat, from a solid close hauled course (and with the boat up to speed), let go of the wheel/tiller (if a wheel be sure the brake is off)...The boat should slowly head up into the breeze. If it goes dead straight, or bears away from the wind, you should add a little more aft rake. If it snaps up suddenly into the wind, you may have too much aft rake (but first double check your main was not overtrimmed!).
Michael-FWIW-your backstay adjuster is not intended to increase mast rake-it is intended to do 2 things: induce (or reduce) mast BEND to optimize mainsail depth, and reduce (or increase) headstay sag. Mast Rake, unlike bend, does not impact sail shape (okay, it can affect genoa clew height), it changes the balance of the sailplan vs. CG of the boat.
What you are seeing when you apply backstay seems similar to rake because the 35-2 mast is so stiff and does not bend much, and you are seeing the top of the rig move aft.. but the best way to do this with the 35-2 rig (if equipped with an adjuster) is to measure the rake with a SLIGHT amount of backstay tension-whatever you would leave on while at the dock. If you want more rake- EASE the HEADSTAY off in 1/2" increments, and measure with the bob. If you do not see any movement, then take up the exact same amount on the backstay, and re-measure.. When you arrive at the desired rake for your next test sail, pin the headstay. Now, when you are under sail you will have the desired rake, and you can use the backstay adjuster to fine tune the headstay sag, and flatten the mainsail with bend-as needed. You will find the mast bends much better with the aft lowers quite loose-as they normally should be..
The rule of thumb is to use headstay length as the determinant for rake. If you do not have a BS adjuster, then when you are adjusting rake with the headstay, be sure you ease or take up on the backstay the same amount when you are done (if you eased the headstay an inch, take up on the BS an inch, etc.). This way the relative rig tune should not change with the change in rake...
Enjoy!
S:nerd:
mherrcat
Contributing Partner
Curious about mast rake for the E30+ also. I downloaded the "Fractional Rig Tuning" document from the Specs & Documents section and there is no mention of mast rake.
I also don't see any mention of pre-bend. Since the rig is fractional and there are no foward lowers or baby-stay I'm not sure there is a way to get any pre-bend in the mast. I guess you could get some rake by lengthening the forestay, but I don't see any mention of it in the tuning document.
I also don't see any upward angle in the spreaders. Everything I've read suggest that the spreaders should angle upward to bisect the angle of the shrouds as equally as possible.
Anyone with rig tuning experience on the E30+ feel free to respond.
I also don't see any mention of pre-bend. Since the rig is fractional and there are no foward lowers or baby-stay I'm not sure there is a way to get any pre-bend in the mast. I guess you could get some rake by lengthening the forestay, but I don't see any mention of it in the tuning document.
I also don't see any upward angle in the spreaders. Everything I've read suggest that the spreaders should angle upward to bisect the angle of the shrouds as equally as possible.
Anyone with rig tuning experience on the E30+ feel free to respond.
Frank Langer
1984 Ericson 30+, Nanaimo, BC
I had hoped that someone (Seth?) might reply to your questions about the E30+, but as they haven't, I'll tell you my experience over the past few years with our 1984 E30+. You are correct that the tuning guide is silent on mast rake and mast bend, and I recall another document I saw somewhere which specifically said there was no mast rake on the E30+. There is a good post somewhere on this site by Seth with good tuning information--a search may show it.
I have done alot of reading and checking websites looking for good tuning information, and it seems to keep coming back to three key principles: 1 ) Ensure the mast is straight from side to side, only perhaps falling off slightly to leeward near the top in a strong breeze; 2) Desireable rig tune avoids lee helm and achieves slight weather helm so the boat will gradually round up on its own; 3) Have the shrouds tight enough to avoid shock loading--ie. the leeward shrouds should just begin to feel (but not look) loose when sailing in a moderate breeze with the boat heeled 15 - 20 degrees.
I have tuned our E30+ like this, but with no mast rake and she sails well, so while I may not be "spot on", I think I'm close. I do have a manual backstay adjuster which induces some mast bend when the wind pipes up, and it does make a difference. I'm also particular about sail trim (boom vang, outhaul, halyard tension, etc.) which makes a difference on these boats.
I don't know if this helps. I would welcome comments from others.
Frank
I have done alot of reading and checking websites looking for good tuning information, and it seems to keep coming back to three key principles: 1 ) Ensure the mast is straight from side to side, only perhaps falling off slightly to leeward near the top in a strong breeze; 2) Desireable rig tune avoids lee helm and achieves slight weather helm so the boat will gradually round up on its own; 3) Have the shrouds tight enough to avoid shock loading--ie. the leeward shrouds should just begin to feel (but not look) loose when sailing in a moderate breeze with the boat heeled 15 - 20 degrees.
I have tuned our E30+ like this, but with no mast rake and she sails well, so while I may not be "spot on", I think I'm close. I do have a manual backstay adjuster which induces some mast bend when the wind pipes up, and it does make a difference. I'm also particular about sail trim (boom vang, outhaul, halyard tension, etc.) which makes a difference on these boats.
I don't know if this helps. I would welcome comments from others.
Frank
Rake on the 30+
I would start with zero to 1" of rake on this guy (determined by HS length of course), and go sailing-Check out my post just before yours for some detailed notes on this, what to do when sailing and further adjustments.
Check it out, try it out, have a rum and coke, and call us in the morning..Our little group here will work it though with you!
As for the spreaders, most are at right angles to the waterline on these boats and are fine, slightly tipped up is OK too.
The HS will only affect rake, not prebend. The only way to adjust prebend with inline spreaders like yours is to adjust the mast step and location of the mast in the partners..mast aft in the base and fwd in the partners will induce prebend,and the reverse will reduce it. How much prebend you want is a function of how your mainsail is designed. More prebend gives you a flatter sail;less gives you a fuller sail. If you cannot get the main flat enough with the outhaul and backstay (if yours is adjustable), then you can add some prebend to flatten the base mainsail shape setting and make the sail flatten more as backstay is added. If the sail is very flat to begin with, do not induce any prebend..
Good luck, and let us know!
S
I would start with zero to 1" of rake on this guy (determined by HS length of course), and go sailing-Check out my post just before yours for some detailed notes on this, what to do when sailing and further adjustments.
Check it out, try it out, have a rum and coke, and call us in the morning..Our little group here will work it though with you!
As for the spreaders, most are at right angles to the waterline on these boats and are fine, slightly tipped up is OK too.
The HS will only affect rake, not prebend. The only way to adjust prebend with inline spreaders like yours is to adjust the mast step and location of the mast in the partners..mast aft in the base and fwd in the partners will induce prebend,and the reverse will reduce it. How much prebend you want is a function of how your mainsail is designed. More prebend gives you a flatter sail;less gives you a fuller sail. If you cannot get the main flat enough with the outhaul and backstay (if yours is adjustable), then you can add some prebend to flatten the base mainsail shape setting and make the sail flatten more as backstay is added. If the sail is very flat to begin with, do not induce any prebend..
Good luck, and let us know!
S
Rocinante33
Contributing Partner
Mherrcat, Frank & Seth,
In the docs & specs section under E-33 are two "E33 & E36 owners bulletins." On these, Don Kohlman of Ericson talked about mast tuning on the fractional rig, both the theory and the practice. Both are very good reading for all of us with fractional rigs (though they may not apply to the earlier questions in this thread about masthead rigs). I know you don't have an E33 or E36, but I think what he wrote still applies to your E30+ fractional. Check it out.
To quote, "The benefits of a properly tuned mast extend beyond the physical laws governing airflow and structure - they penetrate the psyche of the crew."
P.S. He says on the E33 mast rake should be 6". Much more than what Seth is saying for the E30+.
In the docs & specs section under E-33 are two "E33 & E36 owners bulletins." On these, Don Kohlman of Ericson talked about mast tuning on the fractional rig, both the theory and the practice. Both are very good reading for all of us with fractional rigs (though they may not apply to the earlier questions in this thread about masthead rigs). I know you don't have an E33 or E36, but I think what he wrote still applies to your E30+ fractional. Check it out.
To quote, "The benefits of a properly tuned mast extend beyond the physical laws governing airflow and structure - they penetrate the psyche of the crew."
P.S. He says on the E33 mast rake should be 6". Much more than what Seth is saying for the E30+.
Frank Langer
1984 Ericson 30+, Nanaimo, BC
Thanks, Keith. Very interesting bulletin you referenced in the E33 documents section. Now I'm curious as to why the recommended rake on the E30+ is so little (zero to one inch) as compared with some of the other Ericson models. The write-up seems to suggest that some mast rake is essential to good rig tune, so why not for the E30+? Seth, any comments?
Thanks again.
Frank
Thanks again.
Frank
mherrcat
Contributing Partner
The document that mentions zero mast rake on the E30 is the E35-II manual.
The 30+ has a deck-stepped mast, so moving it back to induce pre-bend doesn't seem to be an option.
Interesting about the spreaders not being angled upward.
Most of the mast bend that I was seeing in my rig was occuring above the forestay/headstay. Since there is no backstay adjustment other than the turnbuckle I figured the backstay was set too tight. I eased it off quite a bit and there is still some bend but not nearly as much as before.
The 30+ has a deck-stepped mast, so moving it back to induce pre-bend doesn't seem to be an option.
Interesting about the spreaders not being angled upward.
Most of the mast bend that I was seeing in my rig was occuring above the forestay/headstay. Since there is no backstay adjustment other than the turnbuckle I figured the backstay was set too tight. I eased it off quite a bit and there is still some bend but not nearly as much as before.
OOOPs!
Sorry-I forgot about the deck stepped mast! Prebend (in this case) is created by easing the aft lowers and taking up on the fwd lowers and backstay. It is reduced by taking up on the aft lowers and easing the fwd lowers.
The real question is whether or note you need any-and that is a function the mainsail as I said before. If you can't get the main flat enough with the outhaul, try easing the aft lowers, taking up on the fwds, and adding a little backstay.
Otherewise, as for rake-no 2 frac designs are tuned the same-and rake requirements depend on many things, especially the location of the CG (Keel).
The 33 has the rig pretty forward, and needs a bit more rake to get the CE in line with the CG. The 30+'s mast location puts the CE more or less above the CG to begin with, and needs less rake. They are very different boats, and have different needs in terms of rake.. But having said all this we don't want to complicate things. Go sailing and check things out as we have indicated already in other posts. If the boat has no weather helm (or has a bit of lee helm), then by all means ADD some aft rake. If it has too much weather helm, get rid of some of the aft rake. Don't worry about measuring until you have made some changes-and don't make ANY changes based strictly on measurements-the issue is how the boat sails. Always remember the variables that can influence these basic things: too much weight in either end, blown out sails, or the wrong sized size sails for the conditions...
Sorry for the :nerd: screw up about the mast!
Cheers
Sorry-I forgot about the deck stepped mast! Prebend (in this case) is created by easing the aft lowers and taking up on the fwd lowers and backstay. It is reduced by taking up on the aft lowers and easing the fwd lowers.The real question is whether or note you need any-and that is a function the mainsail as I said before. If you can't get the main flat enough with the outhaul, try easing the aft lowers, taking up on the fwds, and adding a little backstay.
Otherewise, as for rake-no 2 frac designs are tuned the same-and rake requirements depend on many things, especially the location of the CG (Keel).
The 33 has the rig pretty forward, and needs a bit more rake to get the CE in line with the CG. The 30+'s mast location puts the CE more or less above the CG to begin with, and needs less rake. They are very different boats, and have different needs in terms of rake.. But having said all this we don't want to complicate things. Go sailing and check things out as we have indicated already in other posts. If the boat has no weather helm (or has a bit of lee helm), then by all means ADD some aft rake. If it has too much weather helm, get rid of some of the aft rake. Don't worry about measuring until you have made some changes-and don't make ANY changes based strictly on measurements-the issue is how the boat sails. Always remember the variables that can influence these basic things: too much weight in either end, blown out sails, or the wrong sized size sails for the conditions...
Sorry for the :nerd: screw up about the mast!
Cheers
Maybe, but
The 35-2 specs will not give any insight into the 30+, and the in line lowers can do the same thing (but not quite as effectively) as the fwd lowers would (on those that have em)-but remember the lowers, or any of the side rigging, have no impact on rake-only (pre) bend.. ..
Trail and error is the best thing!
The 35-2 specs will not give any insight into the 30+, and the in line lowers can do the same thing (but not quite as effectively) as the fwd lowers would (on those that have em)-but remember the lowers, or any of the side rigging, have no impact on rake-only (pre) bend.. ..
Trail and error is the best thing!