J/30 Class Association

Mast Step Postion

Posted By: Russ Atkinson

Mast Step Postion - 01/04/12 06:30 PM

I would hate to drag my boat all the way to New Orleans next fall just to find out it is not OD compliant. So...
I've measured the positon of the mast step and it appears to be about 1/8" - 1/4" too far forward when measured from the outer edge of the step. When measured to the inner ledge that sits inside the mast I am within spec. In other words I am off by about the wall thickness of the mast.
My issue is that before I tucked the boat in for it's long winter nap, I tried to move the step back. I tried to loosen the screws (phillip head). I even tried using an impact driver to no avail. I am afraid of snaping off the screw heads.
I have tried beating on the mast step with a 5 lb sledge (a block of wood was in between hammer and step)
As a last resort, I saturated the screws and mast step with WD-40 and left that to sit over the winter.

I'm worried that over time that perhaps the stainless steel screws have been corroded/welded into an aluminum plate that is below the mast step. If I break the screw heads off, is there a way to tap for new screws? Other than the danger of igniting the WD-40 and setting the boat ablaze, would heating up the screws help?
Any thoughts?



Posted By: 311 Temptation

Re: Mast Step Postion - 01/04/12 07:24 PM

I too struggled to move my mast step. I believe what happens is that the machine screws are so tight into the solid glass, creating so much heat, that they recure the resin each trip in! I believe that resin hates heat (ironically) & so you will have luck with a torch. However...please DO have a bucket of water handy!!!

Mine proved difficult with an impact wrench but it came out. I would recommend that you install new screws after you move the step. Mine are pretty worked over after reinstallation. Getting them back in was not a ton easier than removal.

When you get the screws out, you'll see that all we have are incredibly long screws run into solid glass. I cannot advise if it would be wise to increase the diameter of at least some of the pilot hole but it seems like it be easier to move the step if so.
Posted By: Rhapsody #348

Re: Mast Step Postion - 01/04/12 07:45 PM

I see no problem with Dell's suggestion of enlarging the hole or drilling new holes. The load is in the shear direction, not pulling on the threads. You might consider over-drilling and installing a stainless threaded insert

[Linked Image]
Posted By: gmo

Re: Mast Step Postion - 01/04/12 07:55 PM

My boat (#112) had the same problem. The bolts were seized into an aluminum plate under the mast step. I'm not sure you want to re-drill, as then you'll have to tap the aluminum again. Also, that's a lot of stainless to drill through.

Min ended up getting rebuilt. The steel into aluminum caused a good portion of the plate to corrode, so after the mast was off for about a month, the upward pressure from the increased volume of the aluminum oxide cracked the step. I ended up digging out the entire mast step, and having it replaced... No aluminum this time.
Posted By: David Erwin

Re: Mast Step Postion - 01/04/12 09:41 PM

The mast step installed in Hull # 87 was not centered in the boat. Keep in mind, a 30+ year old boat can have a possible subtle change in shape. We established center-line from above and with the assistance of a leveled boat with a plum bob moved the step slightly to port. The position front to back was just fine. We drilled (with a level indicator) new holes in the aluminum and used a tap and die set to create new threads. Be sure and use some oil when taping.

I would not recommend rebuilding the step without aluminum. I like machine threads for extra strength.
Posted By: David Erwin

Re: Mast Step Postion - 01/04/12 09:44 PM

Bill, since there is a range adjustment on the step, why not drill new holes?
Posted By: Rhapsody #348

Re: Mast Step Postion - 01/04/12 10:20 PM

Originally Posted by David Erwin
Bill, since there is a range adjustment on the step, why not drill new holes?


Dave - no reason I can think of. I've seen both "fixed plates" that require new holes if they are moved and "slotted plates" that offer an adjustment range.
Posted By: Phil

Re: Mast Step Postion - 01/04/12 11:52 PM

My Boat )Hull #25) had the same problem, when measured in for the NA's in October, the mast step was too far forward. Larry Christie gave me a pass, because performance wise it is actually better to have the mast step further back. That being the case, and as it seems there are a number of boats with this problem maybe it would makke sense to change the rule.
Posted By: Russ Atkinson

Re: Mast Step Postion - 01/04/12 11:54 PM

Thanks folks for the suggestions and input.
My mast step has adjustment slots. In the spring I'll work at getting the screws out and it sounds like if I snap the screw heads off there is a solution. I like Bill's idea of a stainless threaded insert. Although I don't intend on moving it again once it's properly located, at least the next owner could relocate the step with a bit less frustration.
Posted By: cstoddard

Re: Mast Step Postion - 01/05/12 02:10 PM

I think this issue has been well covered We will have NO rule changes in regards to the mast step location.

Posted By: Bob Rutsch

Re: Mast Step Postion - 01/05/12 03:52 PM

The advantage of threaded inserts would be to reduce contact between the screws and the mast step? Would that still work for a step with adjustment slots?

From personal experience it took time, penetrating oil, and an impact driver to loosen the screws. Even with patience it tore up the screw heads. I replaced them with stainless hex head cap screws thinking that would make it easier next time using a socket wrench. Not sure now based on this discussion if that was the best choice but I have no plans to move not that the step is where it belongs. I did have to tighten the step soon after when the mast it slipped aft during a daylong spinnaker run in heavy air.
Posted By: Cap'n Vic

Mast Step Postion measuring - 01/09/12 02:56 AM

So OK ... is this what you guys are talking about... and is this good or bad what you see here???? This hasn't been touched since 1984.

[Linked Image]


Description: Measuring mast step position J30
Attached File
eP1080042.jpg  (1630 downloads)
Posted By: Rhapsody #348

Re: Mast Step Postion measuring - 01/09/12 03:18 AM

Vic. That is legal per class rules:

5.7.3 Position of the mast shall be fixed at the deck 3505 mm plus or minus 13 mm from stemhead tip to the front edge of the mast. And it shall be permanently fixed to an immovable mast step so that the forward edge of the mast is not less than 25 mm aft of the forward vertical face of the molded step in the sole liner.

You are more than 25 mm aft. Effectively this moves the top of the mast forward. Not optimal tune. Read comments in this thread
Posted By: Cap'n Vic

Re: Mast Step Postion measuring - 01/09/12 04:08 AM

this may explain why I can't get to legal max on forestay.
I've always hated light air sailing and this weekend we had 4-9 wind with 3 races where I was not keeping up with boats I had before i changed the roller this season. It currently has too much sag.

Temporarily I will just zonk the forestay a bit shorter to tighten up the sag, which seems to be "enhanced" with the weight of the roller furling. I am currently longer than the old roller but will return to that measurement if not a bit shorter to get more sag out of the forestay. next time i have the mast out will modify.

This may also explain the severe backstay/top batten problem I've had with new mains.

This sound like a workable plan?
Posted By: Russ Atkinson

Re: Mast Step Postion measuring - 01/09/12 06:24 PM

Back to rules for a moment
5.7.3 Position of the mast shall be fixed at the deck 3505 mm plus or minus 13 mm from stemhead tip to the front edge of the mast. And it shall be permanently fixed to an immovable mast step so that the forward edge of the mast is not less than 25 mm aft of the forward vertical face of the molded step in the sole liner.

Since I don't block my mast at the partners,one could argue my mast is not fixed at the deck. Is it class legal not to block the mast at the deck?
Posted By: Cap'n Vic

Re: Mast Step Postion measuring - 01/09/12 07:38 PM

Aaah the dreaded weather helm ....
If you haven't viewed Kid Peel

zip to the start of the close haul segment where 11 year old William is operating at nearly no weather helm running around 5.7 +kts.

It would be really interesting to see ,using a fish scale say for example, just how many pounds is required to point optimally under good wind conditions runing around 5.5kts.

I add this into the discussion as there have been comments that the J30 is not a kid boat and is tiring to sail close haul for most gals. Are we are talking about a very narrow tuning/wind-speed range? that may be related to mast step offset? {also consider that 505 has a modified rudder to somewhat offset weather helm}

later this week Brian J30 #22 and I will be shortening the forestay perhaps as much as 1.5 in. to get some of the wobble out of the forestay. Notice I am not saying sag, but wobble.

we will do the whole thing with back stay and shrouds off. I'm thinking tuning the lowers first to establish a "fixed" point in regard to the forestay ... In othe rwords basically tuning to a forestay length geared to eliminating wobble but a reasonably straight mast.

Posted By: Russ Atkinson

Re: Mast Step Postion measuring - 01/09/12 08:08 PM

We're stepping a bit outside the perameters of discussing rules so someone may way push back - regardless.
Weather helm and balanced helm need to be separated for a minute.
Moving the center of effort fore or aft will induce a need to steer with either lee or weather helm, (in the sense that the tiller/rudder will need to offset the tendancy of the boat to want to fall off or steer to weather. A "balance" of the helm will determine the load on the helm but not the angle of attack of the rudder. By modifying your rudder you have balanced it but I'm guessing that in a 20k blow, with #1 and a full main trimmed in tight, you'd still have "weather" helm
I'm of the beleif that the helm should be pretty neutral and thus adjusting crew weight and sail trim (as in depowering the rig) is faster than sailing with "weather helm"
Posted By: JBro

Re: Mast Step Postion measuring - 01/09/12 08:20 PM

Folks - this is a great discussion. Between the rules and the functional review of how the step, partners, etc. changes affect the way the rig sets up, it's a great overview of how to optimize the boat's performance.

Back when Bill and Dave asked for feedback, one of the things I suggested were more "How-To" articles. Often, great ideas and knowledge are buried in not just one thread but even cross-linked between multiple threads. For a newb visiting the site trying to figure things out, find good guidance, etc. it's not terribly easy to find what's needed to get the boat and rig in tune (and in optimized class conformance). Same for other topics.

It would be great to see folks, as they do these projects, take the content in the threads, their own pics, measurements, and whatnot, and create one document that highlights the process. That would help bring the entire class up to speed, demystify some of the more obscure projects, and help establish authority of a great community and class across all sailing communities.

Some sample topics that jump to mind include:
- Updating the mainsheet to gross/fine trim
- Updating the backstay adjustment controls
- Installing a boomvang/kicker
- Installing new halyard stoppers
- Replacing the standard hatches
- Rebuilding the original Barient winches
- Replacing the fixed portlights

There are some great sites (like Bill's!) that feature some of this content but it would be great to either host some of it on the J30.org site or at least develop more organized links to it.

Creating a new forum post is likely not the best mechanism. What's the best way to create a document like this - with pics - that can then be added to the repository of How-To documents on the site?

Thanks! - Jeff
Posted By: cstoddard

Re: Mast Step Postion measuring - 01/09/12 09:31 PM

In order to get the best up wind performance you want to have the max straight rake in the rig this is achived by have the mast step at min setting (ie as far forward as possible) and the mast as far aft at the deck (mine is set with spar tite) and yes it has to be fixed for the N/A's.

Then you can set the forestay for max lenght. Back stay should be totally loose. With those settings you can follow the tuning guide from your sail maker. I have settings for light (< 10 knots true) medium (8-14) and heavy 14 and up

I only adjust the shrouds not the head stay

That said when we are hard on the wind going up hill the helm is totally balanced (two finger driving) up thru about 13-14 knots

After that the amount of mainsheet trim and travel becomes key to keeping the boat flat and balanced I have never had to two hand the boat when hard on the wind Reaching is a different matter that can be real work

Hope this helps



Posted By: Bob Rutsch

Re: Mast Step Postion measuring - 01/09/12 09:37 PM

I kind of like the give and take here, even the occasional differences of opinion. This being a volunteer, underfunded, and participatory organization the 'do-it-yourself' aspect of the forum helps reduce the need for a moderator or maintenance. If you want something just ask. Anyway back to the rules...

Posted By: Russ Atkinson

Re: Mast Step Postion measuring - 01/09/12 10:06 PM

Thanks Charlie. I have the Spartite in my basement and plan to have it in this spring. But then, I said that last year too.
Looks as if I need to move it up on my priority list from "want to do" to "must do"
Posted By: Rhapsody #348

Re: Mast Step Postion measuring - 01/09/12 10:19 PM

I didn't do the spartite but instead use cedar shingles wedged in the partners with excess protruding cut off to block fore & aft, and shim side to side to keep the pole centered in the hole before any rigging is adjusted. Probably will go with spartite next time the mast is pulled.
Posted By: Cap'n Vic

Re: Mast Step Postion measuring - 01/09/12 10:34 PM

Originally Posted by cstoddard
That said when we are hard on the wind going up hill the helm is totally balanced (two finger driving) up thru about 13-14 knots


Is this with both jenny woolies straight back or are you balancing by slight pinch ala J24? with inner woolies flying high? and flat water?

Posted By: Russ Atkinson

Re: Mast Step Postion measuring - 01/09/12 10:56 PM

Vic it doesn't matter
Rule of thumb (even above 13-14 knots) assume weather helm = slow
depower the rig to achieve no or reduce load on helm.
check it out with your speedo or with one of your tune up partners
While your modified rudder is nice for reducing load on the helm, better for cruising perhaps, for racing, the original rudder design will tell you when to de-power, you can drive by feel
Posted By: JBro

Re: Mast Step Postion measuring - 01/10/12 12:04 AM

@Bill - Re: spartite, you can do it without pulling the rig. It's pretty slick.

Cheers,
Jeff
Posted By: Cap'n Vic

Re: Mast Step Postion measuring - 01/10/12 12:45 AM

Originally Posted by Russ Atkinson
Vic it doesn't matter
Rule of thumb (even above 13-14 knots) assume weather helm = slow
depower the rig to achieve no or reduce load on helm.
check it out with your speedo or with one of your tune up partners
While your modified rudder is nice for reducing load on the helm, better for cruising perhaps, for racing, the original rudder design will tell you when to de-power, you can drive by feel


Actually we prefer to have the boat tell us how to trim into balance, not the tiller ... I know old school ... here is Michael of Belle Faster #537 appreciating a 15 minute no-hands-on-tiller run on a close haul windward for a return spin run a couple of weeks ago. "no hands" I think tops "two fingers"

I was trimming to the feel of the boat and hadn't noticed Michael was running hands off. Probably what we need is more trimmers that also have "feelings"

I drive 505 with the modified rudder about 6 months a year, but 526 still does have the old rudder which is a pain in the ass over 15 with waves, which are conditions that I think most challenging for an old guy.

I also think the modified rudder is helpful in spin runs to control roundups in over 20.

In light wind I find it more rewarding to take a nap, or let the gals and kids drive.

[Linked Image]



Description: No hands close hauled
Attached File
eIMG-20111223-00124.jpg  (1032 downloads)
Posted By: Cap'n Vic

Re: Mast Step Postion measuring - 01/10/12 01:54 PM

Originally Posted by cstoddard
In order to get the best up wind performance you want to have the max straight rake in the rig this is achived by have the mast step at min setting (ie as far forward as possible) and the mast as far aft at the deck (mine is set with spar tite) and yes it has to be fixed for the N/A's.

Then you can set the forestay for max lenght. Back stay should be totally loose. With those settings you can follow the tuning guide from your sail maker. I have settings for light (< 10 knots true) medium (8-14) and heavy 14 and up

I only adjust the shrouds not the head stay

That said when we are hard on the wind going up hill the helm is totally balanced (two finger driving) up thru about 13-14 knots

After that the amount of mainsheet trim and travel becomes key to keeping the boat flat and balanced I have never had to two hand the boat when hard on the wind Reaching is a different matter that can be real work

Hope this helps

OK Back to Topic ... I'm thinking that Charlie has defined the best under 15 set up here.
Which for most of you is probably 85% of your sailing time.

25mm set back at base of mast and forestay at 35' 10.5"
This is then the golden rule??? a starting foundation from where all else must be built???

Because in 99% of the time these two measurements appear to geometrically tied together. We are not going to achieve ideal forestay length/tension unless we have ideal step setback length?

then we can start talking about Shroud tension comparisons because the geometry is duplicateable?

And I think Charlie is right that the sailmakers are using this when they cut OD sails ... which in itself reinforces this golden rule.
Posted By: cstoddard

Re: Mast Step Postion measuring - 01/10/12 05:21 PM

vic

I use this setup for all conditions up thru 30 knots

The only change I make is how tight the shrouds become as the breeze comes up the lowers and uppers get closer to each other

I will also go to max back stay to open up the main and dump some breeze

Of course you also end up maxing out the mainsheet and then use the traveler (windward sheeting car is the only way to go) to dump the breeze in the puffs,

In a steady SW breeze at 20-22 knots you probably will not even have to work the traveler and the helm should be balanced

Posted By: Conundrum

Re: Mast Step Postion measuring - 01/10/12 08:43 PM

Curious, For 2011, my first season, my mast step is at 7/8" set back. I had my mast all the way back in the partners at 11' 6" from stem at the deck. My forestay measured 35' 9 1/2" with RF Unit extended to max.
Backstay completely loose. At this point I am not willing to wrestle with the 1/8 in at the step. (That would be going the wrong direction)But I do not see how I can get the max Headstay length of 35' 10 1/2 ". Will the tension on the uppers get me the 1" to the goal length? I do want max rake and I want a straight mast with very little prebend. Correct?
Posted By: Bob Rutsch

Re: Mast Step Postion measuring - 01/10/12 09:01 PM

I would say we only use max headstay in 0-4 knots of breeze and flat seas. But this is turning into a tuning discussion and it deserves it's own thread somewhere other than the One Design Class Rules, particularly since this forum is only open to owners.

A quick search indicates maybe all this tuning talk would be better off in Mast Set Up/Rig Tension. Could somebody cut and paste from this topic say starting here?
Posted By: Cap'n Vic

Re: Mast Step Postion measuring - 01/12/12 06:29 PM

Don ... it appears that geometrically unless we are at 25 mm setback and solid back at partners ... we will be unable to reach target headstay length ... and have anywhere near enough tension to hold up a RF to work well. You should be just able to do it, considering that -1/8 in. probably is good to kick up forestay tension for a heavier foil. There is only so much tension we can use to pull the mast back with the uppers ... I don't like going over 35s.

Tomorrow we will be resetting #505's forestay as I just didn't realize how critical that mast step measurement is in limiting the adjustablity of the forestay.

I will measure what the forestay with a RF >>>HAS TO BE to look right for a 40mm setback and post.
We are in middle of season here and I am not up to pulling mast to reset this year.

Photo of mast full aft in partners:
[we use cedar shingles wrapped with shrink tape to lock mast position.
Same, same close to 11'6" locked back trying to measure over deck stuff.]

[Linked Image]


Description: J30 recommended mast position at partners
Attached File
eP1110045.jpg  (1340 downloads)
Posted By: Cap'n Vic

Re: Mast Step Postion measuring - 01/13/12 09:45 PM

OK ... after several hours of readjusting with the help of Brian, J30 #22, we are running 35' 7+" forestay with the mast base set back at 40 mm, which we are not going to be able to change until the next time we pull the mast. At which point we will move it to the Min at 25mm. With no backstay on we are looking initially at a pretty straight mast with very little pre bend, basically to see how much bend we can generate with heavy backstay over 15 kts.

We will be working with this setup this weekend on the water, but unfortunately will not be able to tune up against another boat until the regatta the end of the month.

for the purposes of discussion I can't see how we can consider setting the mast step as "tuning" of the rig, but instead consider it bringing the mast into the necessary configuration for racing or maximum accepted performance.

1. If you ask a sail maker to build a J30 #1 they automatically assume headstay is 35' 10.5" because that is what the max head stay is supposed to be, and that gives the biggest sail. So by ordering a standard J30 #1 or even a 155 they expect you to be set up Max. If you are moving sails from one boat to another ... this needs to be the same.

2. to achieve that forestay length the mast step needs to be at 25mm ... there is only so much you can do to bend the mast where it don't want to be bent. So that has to be set at Min. to move the mast at the fractional back enough to get OK tension on the forestay at the target forestay length.
Posted By: Russ Atkinson

Re: Mast Step Postion - 03/12/12 02:01 PM

Back in January I solicited guidance on how to get the screws loosened on my mast step.
I'm pleased to report that after a winter of soaking the screws in WD-40, and with the combination of an impact driver, a 5 lb sledge, a propane torch and a 2 x 4, the screws loosened sufficient for me to beat on the step with the 2x4 and move the mast step back the required 1/8". The step is now OD compliant!

Thanks to all for your suggestions
Posted By: NaturalHigh

Re: Mast Step Postion - 03/14/12 08:53 PM

I tried getting mine loose yesterday with an impact driver with no success. I am 1" too far aft, although the boat seems to go like stink upwind still.

Will beat on it again tonight.
Posted By: dlabrosse

Re: Mast Step Postion - 08/15/12 03:22 PM

I had my mast re-stepped on Friday as my mast was quite far aft from the 25mm standard. The screws did not come undone after reasonable effort with an impact driver, so the rigger simply drilled them out and cut them flush. New holes were drilled and tapped in the proper position. Everything was remeasured and tensioned using the North Sails guide. Looking forward to tonight's race to see if I can point a little better now.
Posted By: Cap'n Vic

Re: Mast Step Postion - 08/15/12 08:21 PM

I am going to do this on Naples Vee Jay next month ... let us know if you notice anything ... but it also involves restoring length of forestay to OD length [longer] ... and that may or may not click with current sail length ... also top of mast further back allows better clearance with the back stay ...

I have harken roller furling which is almost 3 in. shorter than OD forestay length, but enough adjustment to go OD length.

Posted By: dlabrosse

Re: Mast Step Postion - 08/16/12 03:46 PM

Well, last night it blew 16-18 kts and we put up the 140% cruising sail instead of the racing No1 but we were handily outpointing the Hotfoot 30 who had a blade up. Granted I was pinching a little to try and keep the boat flat, and my cruising sail is quite bagged out, but we were still doing 6+ kts upwind. We improved our regular finishing spot despite a less than average start for a respectable 4th position. Boats we beat all have longer waterlines (Hotfoot 30, Spencer 34, Crown 34, Santana 30/30, Wylie 34) which feels good because of the wavy conditions we get with bigger winds. The big winds also allowed us to hold off the competition downwind as the increased pressure allowed us to sail deeper angles. The 34 footers I race against are all mast head rigs and sail straight downwind almost all the time. The gain on the fleet was achieved entirely on the first beat. One issue is that we will likely have to shorten the backstay a little. It took quite a bit of travel before things started to have an effect. A promising start to the new rig tune. Hopefully better results will be coming with our regular 8-10 kts westerly where we can use our proper No1.
Posted By: Steve Buzbee

Re: Mast Step Postion - 08/16/12 04:52 PM

The position of the mast step has an enormous impact on rig tune. 1" of movement forward at the step (assuming the partners are the fulcrum) translates to ~8 1/2" further aft at the top of the shrouds (when the rig is not tensioned). All the tuning guide settings assume the step is in the proper position. If the step is too far aft, the rig will not have nearly enough rake and will have too much prebend when tensioned. I have firsthand knowledge of this-my step was in the wrong place for the first several years that I owned Blue Meanie. Fixing it made a HUGE difference!
Posted By: dlabrosse

Re: Mast Step Postion - 08/16/12 09:12 PM

Steve, that's what I'm hoping for! We'll see next week.
Posted By: Cap'n Vic

Re: Mast Step Postion - 08/16/12 10:52 PM

ditto ... only next month on naples Vee Jay which is moving most of an inch. Why they ever came "random" from the factory is yet to be explained.
Posted By: JBro

Re: Mast Step Postion - 08/17/12 05:20 AM

Any chance that someone who has set things up correctly could post some pics - partners and step? If so, would greatly appreciate it.

thanks! - Jeff
Posted By: cstoddard

Re: Mast Step Postion - 08/17/12 12:05 PM

Guys

Don't for get also to set the Stem to front of Mast to Max 11" 6" +/_ 1/2" This will give you max rake

On the back stay leave it as loose as you can but still allow you to depower the rig when the breeze is on But when you are going down wind you want to allow the top of the mast to go as far forward as possible
Posted By: Cap'n Vic

Re: Mast Step Postion - 10/14/12 09:16 PM

OK ... Am in process of setting the mast step on #505.

If I remember correctly Bill said 25mm from FRONT surface of mast to a extended vertical line at fiberglass step.

This actually puts the step even further forward than this photo from last year.

[Linked Image]
Posted By: Rhapsody #348

Re: Mast Step Postion - 10/14/12 09:22 PM

Vic - here is the class rule for reference. I added the emphasis on the applicable area. This will help you get the rig in the correct position so everything supports OD sails and tuning.

5.7.3 Position of the mast shall be fixed at the deck 3505 mm plus or minus 13 mm from stemhead tip to the front edge of the mast. And it shall be permanently fixed to an immovable mast step so that the forward edge of the mast is not less than 25 mm aft of the forward vertical face of the molded step in the sole liner.
Posted By: Steve Buzbee

Re: Mast Step Postion - 10/16/12 04:10 PM

Vic-you are 9/16" too far aft with your step. That is HUGE! If you move the step forward to the 1" mark as per class rules, the point of headstay attachment on the mast (i.e. the hounds) will move almost 5" aft. This will add rake (obviously) but will also decrease prebend, decrease headstay sag, and will generally help your light air performance. Also-all the standard rig tune settings are calibrated to having the step in the right position. So the rig tune settings you have been using up to this point probably have been way off.
Posted By: Cap'n Vic

Re: Mast Step Postion - 10/16/12 04:58 PM

That's what I'm hoping.

Brian ... skipper of J30 Hornet and my winter tactician last winter was seriously upset with the performance of the boat. He is itching to do a complete re adjust when he gets here in a couple of weeks.

But this all started back in 1985 when I decided that I would not be racing all that much and Don Kidd of Pirate Cove asked a simple question: Do you want to race or comfy cruise with roller furling, slides in main ... etc. and mostly not in sheltered Narragansett Bay but off Beavertail?

Yesterday, they managed to get the mast base off with minimal problems ... the bolts were corroded and had a slight bend. Threads in step appear clean.
The slots in the base appear to be just maxed out for the OD measurement and that's where we will lock it down tomorrow.

[Linked Image]


Description: Mast Step original J30 505
Attached File
eIMG_0656.jpg  (1110 downloads)
Posted By: sailon

Re: Mast Step Postion - 10/18/12 04:32 PM

Reading the posts, some things I don't understand. They are:
"If you move the step forward to the 1" mark as per class rules, the point of headstay attachment on the mast (i.e. the hounds) will move almost 5" aft."-- How is this possible, if (geometrically speaking) the amount of movement of the headstay in the fore and aft direction is fixed by the headstay length, and the length of the mast from the headstay point to the bottom of the mast? I do agree that moving the butt forward will reduce prebend, and also reduce headstay sag, HOWEVER, since our boats are underpowered anyway, why is it important to reduce headstay sag? More sag = more power and higher pointing ability and speed to windward. My experience has been that the setting of the mast butt, (which sets the prebend of the mast) should be based upon the luff curve set in the mainsail, such that the chord depth is controllable in all conditions. In classes such as the Etchells 22 and J-24, the prebend is adjusted (but not universally agreed upon within each class) based upon wind strength. I am not going to re enter the discussion of standard rig settings because they are WAY too tight.

Art Ahrens
Posted By: Cap'n Vic

Re: Mast Step Postion - 10/18/12 05:21 PM

On Vee Jay our most serious concern is headstay sag.
The heavy foil for the Harken RF foil in a 3+ ft wave can wipsaw back and forth ... and while the foil segment connections on the current foil appear to be way better than the old foil using pins ... I am shy as to just how much wipsaw effect i want to have ... you have to see floppy foil action to believe it.

to gain reasonable tension I have shortened the forestay length ~3.5 inches ... which of course makes the OD jenny length too long. We still get some wipsaw action ...

but this move on the Vee Jays part is to one get two boats as close in specs as possible and to try to get to maximum OD headstay length ...

other than that ... other people need to come into this conversation to talk the theory with the idea of course that a carbon foil probably weighs a tenth of the aluminium RF foil.

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Description: Size image Harken cross section RF Foil
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Posted By: D. Bartley

Re: Mast Step Postion - 10/18/12 06:12 PM

If the fulcrum is at the deck, then the tip can move 5" for a small change at the base. However, if the pivot point is at the headstay, then the tip would move less than the base.

I'm with you, think the mast would be pivoting around the headstay, not the deck.
Posted By: sailon

Re: Mast Step Postion - 10/18/12 09:16 PM

Ah ha. I understand. Concern with respect to the head foil can be an issue. Didn't have that worry on a J-24. I have roller furling (Pro Furl) on Nice Pear, and have not seen any issues. HOWEVER, it does raise some fodder for discussion with respect to the hank on jib discussion. In light air, on the J-24, (and it seems to work on the 30), the more headstay sag the better. Does this give the boat with the wire headstay an advantage?
Posted By: Conundrum

Re: Mast Step Postion - 10/18/12 09:44 PM

True, the relationship between the headstay length and the mast step is vital, I wonder if on VEEJAY, the partners are correct. Can you achieve the proper J measurement 11' 6" +/_ 1/2" at the partners. That is the fulcrum point.
Posted By: Cap'n Vic

Re: Mast Step Postion - 10/24/12 12:29 AM

So OK ...
1. reset the step to 25mm [marina mechanic under my 'supervision' ... remember there are not a lot of people who have a hint as to what moving a mast step is in a power boat community ... nice thing about j30 people is we have to know what we are looking to do ... duh only took me 27 years to get to this one. ]

2. quick soda blast, prime and paint ... base looks new.

3. took the forestay out 3in. from where it was -- to a measured length of ~35'8, which pins to the stem 2 in. above the measurement point ... so I am probably a half inch under max 35' 10.5". [It is easier to measure center pin to center pin when off boat. Have 2 treads showing in turnbuckle so didn't get much room to go much beyond.]

4. mast max aft in partners ... measures to 11' 6"

5. tightened starting innners, then outers, then inners loos ~30 ...mast is way straighter than ever has been with a tiny bit of pre bend, minimal backstay tension -- not flopping loose.

6. Tension on roller furling appears to be adequate to avoid foil whip lash ... and tighter than before.

7. will test tomorrow, then regatta against known phrf competitors this weekend.

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Description: Alignment prior to measurement of mast step J30.
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Description: Max forward step position J30.
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Posted By: JeffSmithNJphoto

Re: Mast Step Postion - 12/20/12 02:18 PM

How are the screws attached? Are there imbedded nuts or are they tapped into the fiberglass. I'm afraid an impact wrench will shear the screws. After a month of PB Blaster there is no sign of movement without the impact wrench.
Posted By: Rhapsody #348

Re: Mast Step Postion - 12/20/12 02:25 PM

They are screwed into the mast step directly. If frozen cut off, drill, then fill and drill again.
Posted By: Russ Atkinson

Re: Mast Step Postion - 12/20/12 04:06 PM

There is lots of info in this thread.
Last winter I saturated the four mast step screws with WD-40 (screws all sitting in a pool of WD-40). In the spring I heated the screws with a propane torch and smacked them with an impact driver. Screws came loose
My biggest worry was that I would set the boat on fire when I ignited the screws saturated in WD-40 (I did not):)
I, of course cannot assure you that you won't break the screw heads off, but this technique worked for me
Posted By: dlabrosse

Re: Mast Step Postion - 02/17/13 04:53 PM

When I had the mast step moved on my boat last summer, we ended up cutting the bolts off flush and re-drilling.
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