HR29 Rigging?

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HR29 Rigging?

Postby Chris » Sun Apr 19, 2015 9:01 pm

I know Elad has raised the issue of mast movement but having spent several hours trying to correctly tension my rigging and I am slightly confused by the way HR29 is rigged.

I have long suffered the irritating rattling of the wires in the mast when the boat is at certain angles to the wind due to the mast 'canting'.

Last weekend I went for a shake down sail in a 20 to 30 knot wind. I picked up a mooring for lunch in a tidal river which set me at angle to the very strong wind which caused the mast to shake quite violently which I put down to the lowers not being tight enough.

What I found when I tried adjusting the lowers was that if I tried to tighten them to the same tension as the cap shrouds, it created a negative bend in the mast. No matter how I tried I couldn't achieve the right amount of pre-bend in the mast (or even keep it straight) with equal tension in both cap shrouds and lowers.

I have always thought the rigging on the 29 slightly less robustly equipped than other HRs. I know she is one of the smaller boats but a 312 which lies next to me is real belt and braces job.

So I began to look more analytically at the rig and would like to suggest it is short of either another set of lowers or a baby stay.

With either of these more tension could be applied to triangulate the lower part of the mast and stop it from 'canting' fore and aft as it does so readily at the moment.

I will be consulting the riggers this week for their opinion but just thought it would be interesting to see what views other forum members might have on this.

rigging 2b.jpg
rigging 2b.jpg (60.67 KiB) Viewed 3499 times


In this graphic I have tried to show the fore and aft movement of the mast which occurs, the existing rigging and the suggested additional rigging in blue.

Chris

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Re: HR29 Rigging?

Postby Antti_DD » Tue Apr 21, 2015 10:18 pm

Hi Chris, I have not experienced 'mast pumping' with HR 29 and actually always thought that the mast is actually quite well supported. Of course, the 29 is one of the few HRs with 7/8 rig, so the masthead rigged HRs have sturdier spar with no possibilities for bending at all. I guess that the main problem with the 7/8 rig is that is impossible to get the forestay really tight without running backstays.

However, the negative bend problem is a familiar issue for me also, and therefore I tend to keep some tension in the backstay for straightening the mast. In which order you tighten your rig? I remember reading somewhere about using the backstay tension (while tightening the shrouds) for achieving the right prebend, but now I cannot find the article anywhere and I started to question my method. It would be interesting to hear what the riggers have to say about tuning the mast. DD's mast is currently unstepped so I cannot experiment with different ways.

After the first season I also added a toggle for the forestay to increase the mast rake, but it is difficult to say, whether it had an effect on pre-bend/negative bend.

/Antti
Antti Laine, Forum Administrator
HR 29 # 483 "Dolphin Dance"
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Re: HR29 Rigging?

Postby Chris » Wed Apr 22, 2015 8:25 am

Hi Antti, and thank you very much for your reply because it now begins to make sense if you use the backstay to remove any negative mast bend.

I had a chat with the riggers on Monday and they suggested I may not have enough tension on the cap shrouds and also that I should maintain an amount of backstay tension. I thought the tension on the caps and lowers (according to my loos gauge) should be equal, not that I ever achieved that. Apparently this is not the case and I need to put more tension on to the caps to create the necessary prebend. However, the tension I have is right according to the loos gauge and with the spanner I use, it was becoming difficult to apply any more tension so I felt things were not right. Even in this set-up, I still had mast 'pumping' (your terminology is right, mine was wrong by the way), hence my first post.

The order in which I tension the rig is to loosen everything right off and get the mast straight. Then tension the cap shrouds on each side by 2 full turns and then the lowers, eyeballing the mast to make sure it is remaining straight. I keep doing this, reducing to 1 turn as tension increases then 1/2 a turn, until I have the correct tension in the caps. But this is where things go a little awry with negative bend creeping in. By applying backstay tension, I can now see how this will probably remove that.

I will have another go and see if I can achieve a more acceptable result. I would be interested in what the riggers would do and may well end up having them set the rig up for me if I am still in any doubt. But certainly what you have said Antti makes sense and I think with a bit more experimenting I can tune out the annoying mast pumping.

I have always been able to adjust my rigging satisfactorily on previous boats but admit I have not owned a fractional rig before and I am realising there is a difference.

Impulse seems to have a reasonable amount of mast rake. This I assume can change when new rigging is installed. Impulse had a new forestay and furling gear a few months before I bought her so the riggers may well have set the mast rake then. I hope the toggle helps.

Many thanks Antti

Chris

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Re: HR29 Rigging?

Postby Antti_DD » Wed Apr 22, 2015 9:03 pm

Based on a couple of rig tuning guides that I found online, I guess that the main cause for this initial problem is that loose lower shrouds cause mast pumping and too tight lowers cause negative bend. So the correct trim lies somewhere in between, but of course it is much more complex combination between the caps and lowers. It seems that tightening the cap shrouds increase the prebend and tightening lowers decrease it. Therefore, I have followed the rule of thumb that caps should be tighter than lowers. I don't have a meter to measure the actual tension though, so the tension is based on the feel and observation on how loose the leeward shrouds are when beating to windward. I usually fine tune the caps, when beating during the first shake down cruise.

By the way, I think that I found the article, that was basis for the method that I have been using when tuning the mast: (the main idea is to get the cap shrouds really tight and backstay tension can be used to help with tightening the cap shrouds and getting the desired prebend)

Source: http://www.usspars.com/wp-content/uploa ... igging.pdf

* Check that the mast is upright athwartships in the boat. Use the main
halyard to measure from the masthead to the chainplate each side. Adjust upper
(cap) shrouds to get identical readings each side (but use minimal tension in the
shrouds).
* A certain amount of pre-set mast bend is desirable, to stabilise the middle
part of the mast and thus minimise rig pump in a seaway.
* Ensure the lower shrouds are slack. Induce the required amount of prebend
in the mast by tensioning the backstay. (Make a note of the amount of prebend
by using the main halyard tensioned down to the foot of the mast, and
measuring the amount of bend at the spreaders). Tension the cap shrouds
equally, a few turns at a time, until the fore and aft bend starts to increase. Check
that the mast is still straight athwartships.
* Now tighten the lowers in the same manner as the caps, until the fore and
aft bend starts to decrease. At this stage the caps should be tighter than the
lowers.
* Release the tension in the backstay, check that you are happy with fore
and aft and sideways deflections.
* (Once the rig is set up as described here, tensioning the backstay whilst
sailing will affect the curve in the upper part of the mast only, as the area around
the spreaders is fixed by the opposing forces of the shrouds).
Antti Laine, Forum Administrator
HR 29 # 483 "Dolphin Dance"
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Re: HR29 Rigging?

Postby Chris » Mon Apr 27, 2015 5:52 am

Hi Antti, thanks for this. I am sure it's a useful piece of information to have on the forum for other members and not only my immediate needs. I used a similar guide when I set the rig up a couple of seasons ago.

I have had another go this weekend but quite honestly I still don't think I'm quite there yet.

Trying the method of tensioning the cap shrouds before the lowers didn't seem to make much difference to the end result. As I tightened the caps up, the prebend began to look too great and I began to fear the mast could collapse as the lower part of the mast was effectively unsupported with the lowers completely loose.

I am sure this wouldn't actually happen but there was a lot of prebend and so I put some tension on the lowers to begin supporting the middle of the mast. I then continued to apply more tension to the caps, with a larger adjustable spanner, until I felt they were tensioned sufficiently and with a good amount of prebend in the mast.

With the caps now under more tension, I tightened up the lowers. This took out the prebend very quickly so I then applied some backstay tension which put some mast bend back in.

Although the rig is pretty "Twangy" I am not sure it is right. The caps are pretty tight, the lowers are not exactly flapping in the breeze, the backstay is okay but the forestay I feel needs to be tighter.

The mast still seems to shake in some angles of wind so I am still not convinced I have it right yet.

Please don't think I am looking to you or the forum for the answer as I think it's a case of trial and error before getting it right. I will probably consult with the riggers and ask them to check it over anyway.

It isn't a complicated rig, in that there aren't that many wires, therefore I would have thought the task is not beyond my capabilities but I feel I am 'shooting in the dark' trying to get it right.

I'll let you know how I get on,

Thanks again

Chris

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Re: HR29 Rigging?

Postby Antti_DD » Mon May 04, 2015 4:26 pm

Hi Chris,
This is a great topic since it is good to revise rig tuning practices especially at this time of the year before the coming season. Unfortunately, it takes still at least two weeks before I can put this into practice.

I agree with you that getting the desired prebend is difficult and I have not been fully satisfied with the rig tuning in previous years. However, I am not into sail racing (and getting that last 1 % of boat speed), so my main goal has been getting rid of the negative bend problem and getting the mast tight enough so that it doesn't pump.

I think that the main problem with 29's mast is that it is rather thick or sturdy for fractional rig. My previous boat had similar 7/8 rig and actually most of the boats built in Scandinavia (especially in the 80s) have fractional rig, since tacking in narrow waterways is easier with that compared to masthead rig. However, in other boats that I have sailed, the mast (or at least the upper section of it) is thinner to ease with the bending. So I don't think that 29's rig is optimal for fractional rig and the it is kind of a compromise between an offshore sailboat and a Scandinavian cruiser.
Antti Laine, Forum Administrator
HR 29 # 483 "Dolphin Dance"
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Re: HR29 Rigging?

Postby Chris » Wed May 06, 2015 8:47 pm

Hi Antti,

I think what you say make sense. As I have said my experience with fractional rigs is limited which added to my earlier frustrations.

I haven't test sailed Impulse yet, the weather and tides were not ideal for a single handed sail last weekend.

Feeling the rig, it seemed about right to me. The previous weekend I had pulled and twanged it so many times my judgement became blurred. But I am looking forward to getting out and checking that leeward shroud while under sail.

I am also not a performance geek but I 'm hoping by tuning the rig I can improve forestay tension and reduce the mast pumping.

One other point I mentioned to the rigger was the mast movement at the step that Elad pointed out. Apparently this is not uncommon and can be the result of not enough tension in the cap shrouds.

Chris

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Re: HR29 Rigging?

Postby Tarka Dubh » Sat May 16, 2015 11:18 am

Hi Chris,
I was interested in you post as I’ve had the same problem in the past and it’s taken me a while to sort it out. When I read up on the issue it seemed some rigs are more susceptible to pumping than others, so I assumed that adjusting the rig tension would not make much difference. I therefore purchased a device from one of the big rigging companies (don’t recall which one) that is designed to break up the air flow that leads to pumping. It cost about £100 and is essentially a length of stiff plastic that’s about 10-15cm wide which you hoist up the mast track when you are not using the boat. It’s a real pain to deploy every time you put the boat away and, in my case, did not seem to make much difference.

My next tactic was to attach 10cm pieces of foam pipe insulation to the top section of the spinnaker halyard (there are about 5 in total), and leave this secured to the base of the mast. The foam disturbs the air flow around the mast and also stops the halyard from tapping. Strangely, I’ve had much better results from this. However, having recently had a survey carried out, the surveyor remarked that the cap shrouds where not tight enough as there was no pre-bend in the mast when the backstay is let off. He thought this was probably the cause of the problem and I have since tightened them so some pre-bend is clearly visible without any backstay tension. The lowers have also been tightened, although not as much. The leeward lower and cap shroud no longer go floppy when sailing up wind (which they used to).

I have still got my unsightly pieces of pipe foam in place on the spinnaker halyard, so can’t say for certain that tightening the cap shrouds has solved the problem. But I suspect it has done a lot to help. My only concern now is whether all the shaking has worn the alloy castings that the spreaders sit in, as there is some fore and aft movement. The mast is due to come down next winter, so I think I will replace them just to be safe.

Regards
Tom

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Re: HR29 Rigging?

Postby Chris » Sat May 16, 2015 8:53 pm

Hi Tom.

All very interesting. It is good to have other members sharing their experiences with the HR29's rig foibles.

Last Monday I sailed round to a local river in pretty benign conditions only to hit some real wind on the return passage the following day, 25-35kn. I was beating into it and I didn't see any movement at all in the leward shrouds. Also just prior to embarking on the return leg, I really cranked up the tension on the backstay to pull out any sag in the forestay.

One of the things the rigger seemed to feel while I was chatting about the backstay adjuster was the mechanism might not be powerful enough to pull on the required tension. I am inclined to agree with him. I am now reasonably happy I have the shrouds right with a good amount of mast bend, but I am still not convinced I can apply the necessary forestay tension as easily as one could. Now I feel I have done as much as I can myself, I will be getting the rigger to give me his opinion on the backstay adjuster.

It may just have been wind angle but I laid to my anchor on Monday night. It was really quite windy and I didn't experience the mast pumping as before. So in that respect I think the increased tension in the shrouds has helped.

I can sleep with the rattling but like like you I would like to find a solution to eradicate it. Hopefully the rig tweaking has worked but what do you think about the idea of a removable babystay?

Thanks for your input, much appreciated.

Regards,

Chris

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Re: HR29 Rigging?

Postby Tarka Dubh » Thu May 21, 2015 11:33 am

Chris,
Sounds like you've got it sorted. It seems it's all about the rig tension; something I've never really understood that well. With regard to the backstay tensioner, it appears the original 4:1 system may not be ideal. The surveyor I mentioned said 8:1 would make it easier to adjust to the required tension. He also said its worth tensioning the jIb halyard to help take any sag out of the forestay.
I like the idea of a removable babystay - I guess it would give a bit more support and also provide somewhere to hoist a storm jib.

Regards
Tom

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