DRAGONFLY Trimarans User Forum

We had a scary experience last week when the mainsail of our DF35 could not be lowered on approaching the harbour. With maximum pull and shocks I was able to pull it down using the second reef line, but no further. Without further progress, I got the bosun chair out to release the sail by opening the snap shackle and let the sail drop. We were damn lucky with the calm weather.

On inspection, it turned out that the 10mm dyneema halyard had wedged itself between the sheave and the cheek of the block attached to the top of the mainsail.
The block is a single Selden block, 60mm sheave, plain bearing, and now largely deformed. I have approached Selden, who said that this block should not be used for this purpose; a special 2:1 purchase block should be used instead.
I will need to get a new block and new halyard, as that is likely also damaged.
(the set-up of halyard, block, shackle had been in use for years)

Did anyone have a similar experience?
Any clue what the 2:1 block load capacity should be on a DF35 (65m2 sail)?
There are also 2:1 shackles from Tylaska or Wichard. Any experiences?

Thanks

I will need to get a new block and new halyard, as that is likely also damaged.
(the set-up of halyard, block, shackle had been in use for years)

Did anyone have a similar experience?
Any clue what the 2:1 block load capacity should be on a DF35 (65m2 sail)?
There are also 2:1 shackles from Tylaska or Wichard. Any experiences?

Thanks[/quote]

I used to have similar problems with my DF1000R, extra large main sail 50sqm. Calculated load for the halyard is 20kN (about 2000kg) so you need to be careful when choosing blocks and ropes.

After couple of different kind of blocks and several types of Dyneema halyards I have finally found a good setup:

Block Karver KB series, http://www.bigship.com/catalogue/accast ... arge-kb10c . This block is very short, so there is room for a bigger sail

Halyard Dyneema SK75 diameter 8mm, no overbraid. http://ysm.com.pl/dyneemaropes.html . 8mm is thinnest size to be handled easily and it works fine with my Adersen ST winches. All the previous ropes with overbraid had problems with wear and the overbraid broke down. The result was problems like you had.

Mika, does your Dyneema halyard not slip through the clutch? (which do you have -- Easylock or Spinlock?)

The Karver block look neat -- do you have a pic of how you attach it to the sail? Does the halyard not get out of the groove when the rope is loose?

The Carver stuff is pretty cool, but there are still moving parts - these ones from Wichard are great - I use the smallest one my DF25

http://marine.wichard.com/rubrique-Haly ... 00-ME.html
best regards
Anders

EarthBM wrote:Mika, does your Dyneema halyard not slip through the clutch? (which do you have -- Easylock or Spinlock?)

The Karver block look neat -- do you have a pic of how you attach it to the sail? Does the halyard not get out of the groove when the rope is loose?

The Dyneema rope works fine with my Easylock clutches. It is excellent rope, certified and cheap. The only problem thing is it smells bad for a couple of months , and it looks really cheap also.

The Karver block fits into the mast top fitting so there is more room for bigger sail, please see attached photo. You need to use lashings to control the rope as seen on page 21 of 36 ( http://www.karver-systems.com/en/downlo ... rtdown/19/ )

I think the Wichard MX works fine but the friction is bigger so you need more force to hoist the main.


Please click on any of the photos to see them enlarged!

Thanks, but how do you attach the block to the mainsail headboard -- with a rope shackle?

EarthBM wrote:Thanks, but how do you attach the block to the mainsail headboard -- with a rope shackle?

Rope shackle is too long and slow to operate on top square main when you need to release the top quickly to get it down.
My setup is a Wichard fixed eye quick shackle and dyneema lashing.
http://marine.wichard.com/rubrique-Fixe ... 00-ME.html

Mika Harju wrote:

EarthBM wrote:Thanks, but how do you attach the block to the mainsail headboard -- with a rope shackle?

Rope shackle is too long and slow to operate on top square main when you need to release the top quickly to get it down.
My setup is a Wichard fixed eye quick shackle and dyneema lashing.
http://marine.wichard.com/rubrique-Fixe ... 00-ME.html

I wouldn't trust that type of snap shackle on the main halyard of the DF35 or 1200. The largest might be able to handle the load but I'd stick with one that has a pin, or a trigger release.

To inform the User Forum of the close-out of the query:
I think the failure of the halyard block is due to the overall length of the halyard assembly, comprising of the 80 mm block, a shackle and a snap shackle. The total length was 250 mm. When raising the sail, the block gets pulled against the head plate of the mast and cocks to one side. The halyard can then work its way between the sheave and the cheek. This then stops any halyard movement. (the only thing I do not understand is why it never happened before, as the long assembly had been installed by the previous owner years ago)
For the DF35, I have settled on a Selden 2:1 purchase block, with a 40 mm sheave, 5,000 kgf breaking load and a 10 mm Dyneema line. The block attaches directly to the mainsail top. The length of the block is approx. 83 mm, which is a lot less then the previous 250 mm assembly.
I hope that this change will prevent a repeat of this scary event in which the mainsail cannot be lowered!
Thanks to the people who offered their thoughts and experience.