B&R Reverse Diagonal Tension

[Don Lucas]

As background: I had my mast off a few months ago. None of the "on the ground" settings were changed on the Reverse Diagonals (RD1) etc. and the rig was put back on by the yard and outside riggers they forced me to use. Afterwards my V1 cap shrouds were tighter than they had been before the mast was removed (just by feel), and the lower diagonal shrouds D1 were lossener (based on how far the screws were screwed in). The prebend all looks good and smooth, but maybe more than before the mast was removed.

I finally have gotten underway and sailed in some high winds (all as been on a port tach). On a close reach/reach I noticed my port lower reverse diagonal (RD1) is slack. Everything else looks and feels good and all leeward shroud are tight etc. As I can't think of any reason anything on the windward side of the rig should be loose I tightened a little. But it still is loose and I haven't been out again.

Thinking it through, RD1 is used to set the prebend on the mast before setting the mast. That is the last mention of the RDs in the instructions. The only thing I can think of that would cause RD1 to loosen under sail would be for the bend to increase, as if the headsail tried to reduce the bend RD1 tension should increase instead of loosening. In the directions the cap shrouds (V1) get tensioned first to 15-20% breaking strength and it says this will increase prebend. Then you are to tension the "lower shrouds" (D1) to 15-20% which will pull the lower section of the mast back aft reducing prebend.

So if my D1s are too loose it seems to make sense that the bend under sail could increase beyond that which was set on the ground using the RDs and that RD1 could become slack.

So I'm back to my last thread question of:
-how tight are your D1s?

And now have a new question of:
-do your windward RD1s get slack?

 

[Don Lucas]

Haven't heard back from the local rigging company. So ordered a tension gauge and will just do it myself.

 

[Don Lucas]

On the off chance someone reads this and is interested in the topic:
- tightened my V1s up some more to bring them to 19% of breaking tension (they were ar 16% prior).
- tightened the D1s up from the 9% the rigger left them to 19%
- this also seemed to tighten up the RD1s as they resisted the bend being reduced as the D1s were tightened up

And I'm the proud owner of a $280 rigging tension gauge, which pretty much guarantees that the rigging will never need adjustment again

 

[DayDreamer41]

"And I'm the proud owner of a $280 rigging tension gauge, which pretty guarantees that the rigging will never need adjustment again "

So how much you want for it........

 

[Don Lucas]

"And I'm the proud owner of a $280 rigging tension gauge, which pretty guarantees that the rigging will never need adjustment again "

So how much you want for it........

I'm going to hold on to it till I've gotten a few hard sail days in (I'm a cruiser so that might take weeks). Make me an serious offer for consideration.

 

[Will Gilmore]

- tightened my V1s up some more to bring them to 19% of breaking tension (they were ar 16% prior).
- tightened the D1s up from the 9% the rigger left them to 19%
- this also seemed to tighten up the RD1s as they resisted the bend being reduced as the D1s were tightened up

Congratulation Don. I'm glad everything worked out for you.
It looks like your V1s, along with most of the rest of your rig, were undertight, afterall. How does the prebend look now, compared to before? You said previously, that the prebend looked like it was more than the last time you had it tuned. Did your adjustments change that?

-Will (Dragonfly)

 

[Don Lucas]

tightening the D1s (you know my original question) took out a lot of mast bend

One of the overall lessons was: the rigger was the first time a "professional" has worked on my boat in the 9 years I've owned it. All they did was get paid to screw up my boat!

 

[Will Gilmore]

All they did was get paid to screw up my boat!

That is often my experience with professionals. In my career as an independent professional, I use to tell people, "I charge for my mistakes, I just don't charge to fix them. "

-Will (Dragonfly)

 

[Don Lucas]

$220

 

[Don Lucas]

Have spent a few 24+ hour sails sailing hard since adjusting my rig to the tensions as noted in the thread. If you do the same your rig is going to be just fine and there will be no need to adjust under sail as the leeward cables are going to remain pretty tight.

It's as simple as that and probably well worth it to an owner to read up on, buy a good tension gauge, and do it themselves as it is to risk letting the "pro" learn on your boat. I told my "pro" what I had learned and they admitted they they didn't know (used different words that equaled this).

 

[DayDreamer41]

On the off chance someone reads this and is interested in the topic:
- tightened my V1s up some more to bring them to 19% of breaking tension (they were ar 16% prior).
- tightened the D1s up from the 9% the rigger left them to 19%
- this also seemed to tighten up the RD1s as they resisted the bend being reduced as the D1s were tightened up

And I'm the proud owner of a $280 rigging tension gauge, which pretty much guarantees that the rigging will never need adjustment again

@Don Lucas I did buy a gauge, figured that it wouldn't be such a bad thing to have, I am sure it will get put to use around the club as well as for each springs tune up.
Anyway this past weekend the sail loft delivered my new sails and in talking with them they suggested I back both the V1's and the D1's off (especially the D1's) check that the mast is in column, which it is, then set my V1's to 18%, then I set the D1's to 18% measured the prebend in the mast and it is now a nice smooth evenly distributed 2" at the midpoint between the mast head the the goose neck (was closer to 5" before adjustments). Once this was done I went back and looked at the V1's tension, they had dropped back to about 12%?? which is opposite to what I thought would happen. But the mast is in column and has what is prescribed for prebend on a furling rig so the next thing is to go out and sail it and see if everything stays taunt.

 

[Bill19233]

Last race I noticed the windward RD1's were going slack when close hauled on both points of sail. Local rigger that I trust and is familiar with B&R rigs is going to tune and inspect this week, it's been three years. He thought I was confused and that the leeward ones were going slack and said that's normal to see a little slack. Had to show him this 30 second video that it is the windwards. I don't think he's seen the windward RD1's loose before.

You have to watch real close, but you can see it flop around if you're watching in 1080. I'll update with whatever they tell me they found and adjusted. They're tight as can be when sitting at the dock.

 

[Don Lucas]

@Don LucasOnce this was done I went back and looked at the V1's tension, they had dropped back to about 12%?? which is opposite to what I thought would happen.

When I did mine, tightening the D1s didn't change the V1s tension at all

 

[RoyS]

"And I'm the proud owner of a $280 rigging tension gauge, which pretty guarantees that the rigging will never need adjustment again "

You are correct. You will never need it it again and it will not fit in your tool box either. Do the right thing and toss it over the side.

 

[Don Lucas]

sold it for the $220 I posted