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| Home >> Technical >> Boom dyneema loop questions |
21/12/2024 20:26:00
Russell
Posts: 19
I think, that the RS homepage is correct.
The vang ist fixed with one 5 mm at the mast, then two 4 mm on the boom should be O.K.
That is also the size I have on my original equipement.
Could be by the was difficult to feed the 5 mm line at the boom through the hole, which is made for 4 mm. Anyhow, the holes are quite tight.
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The vang ist fixed with one 5 mm at the mast, then two 4 mm on the boom should be O.K.
That is also the size I have on my original equipement.
Could be by the was difficult to feed the 5 mm line at the boom through the hole, which is made for 4 mm. Anyhow, the holes are quite tight.
Reply
21/12/2024 16:32:00
Michael Heber
Posts: 71
I just got a reply from Selden on the RS Aero spar dynema loop diameters;
Boom:
Main vang = 5mm, 30mm loop
Two block vang attachment = 4mm, two 80mm loops
Mainsheet blocks = 3mm, two 80mm loops
Mast:
Vang = 5mm, 55mm loop, Diamond knot
Slightly different from the RS Parts site, but that still appears adequate too.
Dont forget the bent washers under each stopper knot to spread the load.
Reply
Boom:
Main vang = 5mm, 30mm loop
Two block vang attachment = 4mm, two 80mm loops
Mainsheet blocks = 3mm, two 80mm loops
Mast:
Vang = 5mm, 55mm loop, Diamond knot
Slightly different from the RS Parts site, but that still appears adequate too.
Dont forget the bent washers under each stopper knot to spread the load.
Reply
20/12/2024 22:25:00
Peter Barton
Posts: 5114
You can find this in this link:
https://www.rssailingstore.com/Catalogue/RS-Parts/RS-Aero/Masts-Parts
Boom 4 mm, Mast 5 mm
Reply
https://www.rssailingstore.com/Catalogue/RS-Parts/RS-Aero/Masts-Parts
Boom 4 mm, Mast 5 mm
Reply
20/12/2024 09:53:00
Michael Heber
Posts: 71
Peter, Ron, Michael, thank you for your help! I had a friend measure the distance between the holes and he said it was 5 inches (basically 125mm) so I could dteremine which one was the original hole. I made the loop with a diamond knot and made a loop with the tails to really tighten the knot. Then I taped a bent stainless steel washer so that the bend would sit correctly inside the boom with the loop oriented correctly. I fed a fish tape from the hole to the end of the boom to pull the loop and it took a couple minutes. I want to pull another loop through the extra hole and use it to attach a shock cord going through the clew to help ease the outhaul, but I'm assuming that's not legal. Again, thanks for all the help!
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19/12/2024 17:53:00
Oscar
Posts: 5
Without wishing to hijack this thread, are the mast and boom loops the same size dyneema? The RS Aero Spar Parts page gives a different size for mast and boom while the parts workbook says that they are the same size.
Thanks.
Russell
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Thanks.
Russell
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19/12/2024 10:51:00
Russell
Posts: 19
Hi Oscar,
There should only be two holes in the boom for the vang attachment. I have just checked and they should be 125mm appart.
I presume during a replacement the previous owner struggled to pull the loop through one hole as it is deliberately tight to avoid wear and weakness. The way yours is now will not be at all good for the boom.
You ought use only the hole 125mm from the other one and pull a dynema loop through with a mousing line. If it is super tight to pull the loop through then it can be achieved using a very thin and strong mousing line [you could use a few strands taken from a dynema rope for the last bit to pull it through, if necessary]. Be sure to use a backing bent washer under the diamond stopper knot. Pull the knot super tight and have long tails behind it as dynema can be slippery and knots can slip a little under load.
Reply
There should only be two holes in the boom for the vang attachment. I have just checked and they should be 125mm appart.
I presume during a replacement the previous owner struggled to pull the loop through one hole as it is deliberately tight to avoid wear and weakness. The way yours is now will not be at all good for the boom.
You ought use only the hole 125mm from the other one and pull a dynema loop through with a mousing line. If it is super tight to pull the loop through then it can be achieved using a very thin and strong mousing line [you could use a few strands taken from a dynema rope for the last bit to pull it through, if necessary]. Be sure to use a backing bent washer under the diamond stopper knot. Pull the knot super tight and have long tails behind it as dynema can be slippery and knots can slip a little under load.
Reply
17/12/2024 15:09:00
Peter Barton
Posts: 5114
@RonF 'Delphine'
That is exatly the way I did it for the mast. So there is also a washer in the boom.
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That is exatly the way I did it for the mast. So there is also a washer in the boom.
Reply
17/12/2024 13:30:00
Michael Heber
Posts: 71
Hi,
I have previously replaced a vang loop, because leading edge of the dyneema was half cut through by compression against the leading edge of the hole in the boom/internal bent washer.
The way I did this, was:
1. tie a long thin but strong line / thread to the dyneema loop that hangs down through the boom (pick the correct hole, not the illegal one) ;
2. remove outhaul cap at far end of boom, furthest from the mast ;
3. Push / work the dyneema loop back into the boom;
4.stand the boom on end and shake the loose dyneema loop out to the end of the boom - still attached to the thin line (make sure you have tied off the other end of the line so it still comes out where the original hole is) ;
5.tie your new loop to your line at the far end of the boom (the washer will most likely be still somewhere on the line? BUT: given the previous bodgy repair, perhaps the washer is lost? STRONGLY RECOMMEND you ensure replacement washer same shape and spec, if original is missing);
6.drag new dyneema loop back up the boom and through the hole in the boom into correct position (you might have to gently work loop through the hole - it's a tight fit, so your leader line needs to be thin enough not to obstruct, but strong enough not to break)
7. Replace boom outhaul cap, etc.
BONUS POINTS:
1.gently round off inside sharp edges of the washer, just a bit, too minimise future cutting?
2. dubious, class legal? Same treatment for the sharp edges of the hole in the boom?
3.if tying your own new dyneema loop:
- leave long tails so you can get REALLY good purchase to tighten the diamond knot (I thought I got mine REALLY Tight, but still some worked through);
- maybe stitch and whip the tails to further prevent any possible pull through (I recently had an RS supplied granny stopper knot, at base of mast, finally pull itself through and undone, on an 8 year old, frequently sailed boat!).
Hopefully this helps.
Cheers, Ron F
Reply
I have previously replaced a vang loop, because leading edge of the dyneema was half cut through by compression against the leading edge of the hole in the boom/internal bent washer.
The way I did this, was:
1. tie a long thin but strong line / thread to the dyneema loop that hangs down through the boom (pick the correct hole, not the illegal one) ;
2. remove outhaul cap at far end of boom, furthest from the mast ;
3. Push / work the dyneema loop back into the boom;
4.stand the boom on end and shake the loose dyneema loop out to the end of the boom - still attached to the thin line (make sure you have tied off the other end of the line so it still comes out where the original hole is) ;
5.tie your new loop to your line at the far end of the boom (the washer will most likely be still somewhere on the line? BUT: given the previous bodgy repair, perhaps the washer is lost? STRONGLY RECOMMEND you ensure replacement washer same shape and spec, if original is missing);
6.drag new dyneema loop back up the boom and through the hole in the boom into correct position (you might have to gently work loop through the hole - it's a tight fit, so your leader line needs to be thin enough not to obstruct, but strong enough not to break)
7. Replace boom outhaul cap, etc.
BONUS POINTS:
1.gently round off inside sharp edges of the washer, just a bit, too minimise future cutting?
2. dubious, class legal? Same treatment for the sharp edges of the hole in the boom?
3.if tying your own new dyneema loop:
- leave long tails so you can get REALLY good purchase to tighten the diamond knot (I thought I got mine REALLY Tight, but still some worked through);
- maybe stitch and whip the tails to further prevent any possible pull through (I recently had an RS supplied granny stopper knot, at base of mast, finally pull itself through and undone, on an 8 year old, frequently sailed boat!).
Hopefully this helps.
Cheers, Ron F
Reply
17/12/2024 08:13:00
RonF 'Delphine'
Posts: 35
Here you can see in the spare parts list, how it should be:
https://www.rssailingstore.com/Catalogue/RS-Parts/RS-Aero/Masts-Parts
The additional hole looks completely wrong for me.
I assume, that it was drilled instead of making a correct repair, when the dynema loop was worn out.
My suggestion is to rework it to the original status. I would not feel well, because the load is different on the boom as well as it is for sure not class legal.
Once you send me the measurement of these two holes (e.g. the distance from the other vang loop, which looks correctly, I can tell you, which hole is the correct one.
I am not sure, how this is fixed in the boom, because I only changed these lines at the lower Mast. There was a washer inside the mast, maybe this should also be there. Hopefully someone else knows details regarding this.
Best regards from Germany
Michael
Reply
https://www.rssailingstore.com/Catalogue/RS-Parts/RS-Aero/Masts-Parts
The additional hole looks completely wrong for me.
I assume, that it was drilled instead of making a correct repair, when the dynema loop was worn out.
My suggestion is to rework it to the original status. I would not feel well, because the load is different on the boom as well as it is for sure not class legal.
Once you send me the measurement of these two holes (e.g. the distance from the other vang loop, which looks correctly, I can tell you, which hole is the correct one.
I am not sure, how this is fixed in the boom, because I only changed these lines at the lower Mast. There was a washer inside the mast, maybe this should also be there. Hopefully someone else knows details regarding this.
Best regards from Germany
Michael
Reply
16/12/2024 22:55:00
Michael Heber
Posts: 71
I recently picked up 3785 and I think the previous owner rigged it differently. The boom has 5 holes for dyneema loops: two for the mainsheet blocks and three for the vang. Is it supposed to only have two for the vang? On my previous boat I don't remember the loop tied outside the boom. The rigging manual doesn't show this extra hole either. I'm thinking about replacing it with a 4mm loop with a diamond knot and a bent washer inside (going through a single hole). Which hole should I use? Any information or suggestions would be appreciated.
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15/12/2024 02:08:00
Oscar
Posts: 5
