Sailing technique; tired of bending mast sections

[L Razor]

My son has been sailing his Radial for a couple of years and he has now gotten to the point where he is bending his mast sections (upper and lower). I am pretty sure that he is bending the mast 'cause he is putting the vang on too hard. He has been told to put the vang on hard in 20+ and we were down in Corpus recently and ... you get the idea. (He did NOT stick the sail/mast in the mud to cause this) The upper he bent this time was a European upper and is less than 3 months old. With the new controls you can obviously overdo the pressure and damage the spars and sails.

My question is how do you know what is too much pressure on the controls? Do you try to put on just enough pressure to control the sail but no more to damage it? Is bending the spars inevitable in high wind conditions?

 

[Chainsaw]

If all else fails, take the new flash 15:1 vang off and give him a 6:1 or something similar.

That'll slow the little gorilla down.

Then force him to go sailing more often so he finds out for himself just how much vang is necessary for his rig, instead of listening to people who say:

"soon as it gets windy you need heaps of vang..."

Well, what the hell is "heaps"? You won't know till you experiment, and the solution will incorporate more than just vang tension, I'm sure. As far as I know, heaps of vang is a well known killer of radial topmasts and is not recommended.

With a less powerful vang he may learn something he's missed so far,and you can spend your money on ear plugs to blot out his squealing that "it's too hard" instead of spending your money on new upper sections.

 

[Ross B]

rotate the bend every time to straighten the bend best you can every sail

 

[Clive Humphris]

I agree with Ross that it is a good idea to rotate the top section every sail. If you have been placing the collar rivet to aft you need to be careful with this suggestion though as it is not a good idea to place the rivet towards the bow as the rivet hole is under tension and is a stress raiser. My practice is to place the rivet to the side, alternating starboard and port each sail. This puts the rivet on the neutral axis and thus the minimum stress area. Since doing this I have had no problem with permanent bend on a Radial. Upwind in a blow I vang sheet to keep the boat upright. This technique needs a fair amount of vang pressure and is the way the boat should be sailed.

 

[Josef]

Don't rotate it, that will just make it break after a wile.
Just take the mast and put the top of the topsection on something reasonably high then put your weight somewhere around the middle of the mast. It has always doen the trick for me anyway.

 

[Atlas]

A daughters friend of ours went through seven radial bottom sections last year.
I wonder if this carbon mast idea will work this problem out...

 

[L Razor]

Yikes! Seven lower sections in a year....this is starting to cost real money.

Regarding the question of technique; vang sheeting is what to do in heavier winds and I would guess that you need to put on the least amount of vang pressure needed to achieve this. The question is how do you tell what is enough and too much vang?

Another note: I placed some wear strips on the lower mast section that have the effect of shimming the mast forward some; I am NOT going to use those again.

And another note: I was thinking that rotating the rivet was a good idea and the thought occurs to me that you can rotate the rivet anywhere on the stern half of the orientation that would be in compression. Does the upper section rotate some when you sail and do you need to tape the section to reduce rotation? Both times he has broken upper sections the failures appeared to have emanated from the rivet. I am confident he did not start with the rivet oriented to the bow; might the upper have rotated to the front?

Thanks for all the comments and input!

 

[Josef]

A daughters friend of ours went through seven radial bottom sections last year.
I wonder if this carbon mast idea will work this problem out...

What the hell? Is she to heavy for the radial or something, cause that just shouldn't happend.
I never managed to bend my radial bottom untill after I had switched to standard mainly and was to heavy for radial (so I guess I put to much strain on the mast).

 

[abenn]

Clive - re putting rivet hole to the side. This sounded like a good idea to me, so I did it with my new top section which I bought about 15months ago. This section snapped off a few weeks back in about 15-20 knots - vang not fully on ad not really over-powered at all - no one else broke any gear that day. Its very clear that the break started at the rivet - oxidised surfaces for about 5-10mm on either side of the hole and then the rest of the mast just ripped off. There was even a small bit left clinging on opposite the rivet hole. There was no rusting around the rivet at all - all kept nice and clean and rinsed.
I wonder that even though the hole itself might be at the neutral bend point, just to either side of it will be in compression or tension - and constantly changing as the mast flexes fore an aft. Then when you swap sides the type of stress changes. Won't even these low levels of varying stress cause the infamous Aluminium fatigue failure ?
I'm going back to rivet at the back with my new section.
I even posted bottom bit of the failed top section to the aussie manufacturers to get their comments, but of course they ignored it completely - no email nothing. Once its sold any breakages are all our fault.
I also heard a rumour that there is no such thing as an aussie spar any more ? Their was a problem with the extrusion die and all aust spars are being imported from Europe.

 

[AAHF]

Be careful with downgrading his vang to the old style. First off, he will still be able to get plenty of mast bend going. Speaking from experience, he will be able to go block to block using just the mainsheet if he wants to, and then once he locks the vang in place he'll be right back at full mast bending power. Also, when he returns to a 15:1 vang, he will be used to his less powerful vang, and may initially trim it even harder than before, not realizing how little effort it takes relative to the older style vang.

 

[Cindy Taylor]

I agree with Ross that it is a good idea to rotate the top section every sail.

My husband decided that he rotate the rivet of his top section for each sailing session and did that for some time before going out in 30+ mph winds. The top section snapped when sailing in the high winds, ripping the sail. Someone took the top section to his place of work to have a metals expert look at it and they determined that rotating the top section actually weakens the aluminum metal. The metals expert said that rotating the top section actually made the aluminum weaker since you are bending the section back and forth. This has been discussed on the forum before.

If you sail in salt water you should rinse your metal pieces off with fresh water. I just had to replace a lower radial spar at $265 because of corrosion at the vang tang rivets. Last year I did not have access to fresh water so I stopped rinsing my boat and spars. When I finally did start rinsing off my boat again I noticed a fine crack in the spar at the vang tang rivet.

 

[Clive Humphris]

Abenn – Sorry to hear about your mast failure. You say you have had the section about 15 months. With this section have you always placed the rivet to the side alternating port to starboard? How much usage and what type of conditions do you sail in? Do you always high pressure wash the rivet area to alleviate salt corrosion? Is it on a full or Radial and, if its not too personal, what do you weigh?

In July 2005 I wrote in the carbon section thread:-

“ I sail a Radial in Victoria, Australia, weigh 67Kg, and wind conditions mean I sail with high vang pressure say about 50% of the time. I sail most weekends in club races, October to April, 2 or 3 significant weekend regattas like Masters and States and a week long summer series. This program would be typical for a reasonably keen racer I believe.

I have found the upper section to be reliable only with the following maintenance programmme:-
1. Regular after race high pressure wash of the collar joint to help minimise salt water corrosion.
2. After a high wind day I normally have to straighten an approx. 50mm tip permanent set to maintain straight.
3. At the end of every season I end for end the spar, enabling an extra year of life.
4. I do, of course, always install the pop rivet on the collar to aft so that the pop rivet is on the compression side of the spar.

I draw the following conclusions from this:-
1. With my usage on high wind days the aluminium in the collar area is taken beyond the yield point stress level. This leads to metal fatigue and limits the life of the spar.
2. The reliability of the spar is adequate for me providing I stick to the above programme.
3. I need to fund a new spar every 2 years.
4. This experience is particular to my usage and the spar materials I happen to have. Because the design would appear to be marginal it would only take small changes in material temper and/or wall thickness and usage to make the life unacceptable for some sailers.

Based on this I would recommend that:-
1. A carbon spar would be a welcome change assuming that the fatigue life is greatly increased and the stiffness characteristics are close to the existing aluminium spar.
2. As long as the carbon spar is no more than double the aluminium price it would justify itself just on the ecomomics of ownership alone.
3. The added advantage is less maintenance mucking around.
4. The stiffness characteristics could be modified at the margin to make the boat more sailable for a slightly lower sailer weight range.

I hope my snapshot view of this problem helps”.

As you can see, I was having permanent bend problems with the rivet at the back strategy. My reckoning at that stage was that the section needed end for ending every 12 months to achieve reliability. For the following season I rethought this strategy and went to the rivet at the side. I wrote:-

“You may also want to have a look at the previous threads on this subject. One important subject is the placement of the sleeve rivet. A lot of people place this facing the stern of the boat ie on the compression side. Being an engineer I think a better solution is to place the rivet on the side, on the neutral axis, where there is a low stress level. I like to alternate between the starboard and port sides to maximise the fatigue life. The other item is corrosion. Always wash the gap between the sleeve and the section with water to get rid of the salt.

Re sideways bend I have concluded that the sideways deflections and hence stresses are several times less than the rearward deflection hence my recommendation. A poorly maintained top spar will break whatever direction the rivet is placed.”

Since doing this I have had far less permanent bend problems and zero breakages. This doesn’t mean, based on my experience alone, that this is a bomb proof strategy. I still believe that the design is marginal at best and I would like to see a design change to improve its robustness.

This could mean that we should:-
1. Get the Carbon upper section back on the agenda or
2. Design a non rivet collar or
3. Introduce a short reinforcement sleeve

Lack of action on this subject does the reputation of our class no favours.

I would like to hear others opinions on this.

 

[abenn]

Clive - I sail in Perth,WA mostly on the river, so if you are familiar with our sea breezes you'll know our conditions. I sail most sundays in summer + a few all weekend regattas + training once a week. So it sounds similar to what you do. We regularly get a 15-20knot seabreeze in early summer, weaker after xmas. I sail radial, weigh 68kg. So the vang is regularly pretty tight, but not often past B-B. As I said, for that last new section I placed the rivet to the side for its whole (short) life. I never had any issues with it getting bent. I always rinsed it with fresh water - not always high pressure tho - only if I'd capsized.
Its probably just the variability of manufacture, I was unlucky. Maybe this one I'll end for end after 1 year as you suggest. That extended collar that doesn't need a rivet would solve all this. Or the carbon section as you suggest.

 

[Merrily]

A poorly maintained top spar will break whatever direction the rivet is placed.”[/I]

Since doing this I have had far less permanent bend problems and zero breakages. This doesn’t mean, based on my experience alone, that this is a bomb proof strategy. I still believe that the design is marginal at best and I would like to see a design change to improve its robustness.

This could mean that we should:-
1. Get the Carbon upper section back on the agenda or
2. Design a non rivet collar or
3. Introduce a short reinforcement sleeve

Lack of action on this subject does the reputation of our class no favours.

I would like to hear others opinions on this.

A new composite upper spar is being tested right now. See SFBayLasers post http://www.laserforum.org/showthread.php?p=34586#post34586

 

[bjmoose]

The composite upper is currently proposed only for Radial sailors.

As far as the original poster's question goes, I'm a little surprised that no one has offered the following that I picked up from somewhere (class association booklet they mailed me when I became a member?)

Anyhow, the idea is that at the top mark, on a windy day, you need to ease off some vang you've been carrying upwind *before* you turn downwind, or you're at considerable risk for bending upper mast sections.

 

[L Razor]

The composite upper is currently proposed only for Radial sailors.

As far as the original poster's question goes, I'm a little surprised that no one has offered the following that I picked up from somewhere (class association booklet they mailed me when I became a member?)

Anyhow, the idea is that at the top mark, on a windy day, you need to ease off some vang you've been carrying upwind *before* you turn downwind, or you're at considerable risk for bending upper mast sections.

The carbon upper does sound very interesting, but until it is out we will all have to deal with this issue. It this issue more of a problem with Radial? My son is 140 pounds (64 kilograms) so he is not quite at the point where he can go into full rig yet.

I hate to generalize but it appears that the advice is in heavy winds (15kn+) to vang on enough to go block to block upwind then release vang prior to rounding the WW mark; then vang on just prior to or after rounding the LW mark?

Thanks for all the advice.

 

[184254]

I sail a full rig and have not had a problem with too many top sections breaking. I feel that the critical factor is not releasing enough vang tension before rounding the top mark. I like to ease it as soon as I am on the layline, but this is not always easy. Hope this helps.