UK-Cherub Forum

Cherub Chat => Tech Chat => Topic started by: Ben Howett on February 19, 2008, 04:40:42 PM

Title: Rig Tension
Post by: Ben Howett on February 19, 2008, 04:40:42 PM

The boats going back to the club this weekend to hopefully get some sailing in and I thought id take the opertunity to neaten up a few splices and get my rig sorted out finaly - It still feels like im running too little rig tension after my slightly nervous first few sails following the rebuild so thats the first thing i want to get sorted before I start changing antyhing else - what kind of range should I be aiming for?

I ran around at the nationals with an old loose guage but got a huge range of values - probibly because the guage was just getting tired and old more than anything else. Does anybody (particualy those with older boats) have any reasonably accurate values?

Cheers

Title: Re: Rig Tension
Post by: mathew_harris on February 19, 2008, 04:51:00 PM

think i'm running 400-500 lbs through Sweet Dreams although i think Stu was running a lot more tension, i wimped out and let it off a touch the first time i rigged the boat.

Title: Re: Rig Tension
Post by: roland_trim on February 19, 2008, 04:54:18 PM

Get Dr Lee to tension your rig. Following this you'll either have a broken boat or confidence to pull on as much as you physically can in the future. Plus if it breaks he has probably saved you loosing the mast on a gusty day.

Title: Re: Rig Tension
Post by: ghislain_devouthon on February 19, 2008, 05:08:29 PM

I had the same issue as you after building NBS.

All is a matter of confiance more than aiming a strict value.

Actually at the national I put a mark on my boat breaker rope under tension. The mark was just outside the last pulley about 1m up the snout.

Everyday I pulled 20 cm further.

At the end of the nat, the mark was 30 cm under the snout  :o :o :o.

Actually the right tension is when I can't pull on my 6:1 purchase anymore (eg we could imagine it is a 300 kg tension).

Title: Re: Rig Tension
Post by: Stuart Hopson on February 19, 2008, 05:24:24 PM

I use loads, not changed the settings on atums tension yet as i'm still getting used to the rig but, the normal aproach is pull on as much as you possibly can... and then a little more, its scary the first few times though.

Title: Re: Rig Tension
Post by: neal_gibson on February 19, 2008, 07:14:21 PM

last time i checked i had about 30 looes on suicide blonde if that helps ben and 130lbs on the caps however i dont realy ahve any accurate settings as i am still fiddling

Title: Re: Rig Tension
Post by: Tim Noyce on February 19, 2008, 07:20:30 PM

I was using 36 on the Loos but after a... erm, 'few' mast breakages I have dropped down to 32. Rig doesnt seem to behave much differently. I have a seperate jib cunningham which i wang on like a mo fo to get the jib tension right. After having taken it to Alverbanks he recommended I have at least 6:1 on my jib cunny to get it to have any shape... nutter. Looks good now though.

Title: Re: Rig Tension
Post by: Ben Howett on February 19, 2008, 07:28:01 PM

Cheers guys... Il have a look this weekend and see how brave I get.

For Neil and Tim... is that old school model A Loos guauges or the new  PT -1 spring powered ones?

Title: Re: Rig Tension
Post by: Tim Noyce on February 19, 2008, 07:29:49 PM

erm, mine is an old skool bendy metal superspars one... no springs attached

Title: Re: Rig Tension
Post by: Will_Lee on February 19, 2008, 08:31:34 PM

Of course, even a special springy Loos gauge is probably only accurate to about +/-10% in ordinary usage.

Tap the top bit of the main shroud between the hounds and the spreader with something metal like a car key. Quite suddenly (at about 33 on the Loos) it'll start making a sound which is defo a low musical note. That's a good place to start for rig tension.

Title: Re: Rig Tension
Post by: neal_gibson on February 19, 2008, 09:00:59 PM

yeah it was an old school bendy loos gauage like the superspars one

Title: Re: Rig Tension
Post by: Phil Alderson on February 20, 2008, 08:47:13 AM

when you are doing this remember shrouds do tension forestay does rake

Title: Re: Rig Tension
Post by: phil_kirk on February 20, 2008, 11:13:49 AM

I've been putting more tension on slippery although due to the gunnels the shroud base is just getting narrower.

(thanks for the advice on the other thread guys.  There is already a peice of timber between the skins on that section of the gunnel so I will try more layers of carbon and perhaps attach the lowers plates seperately).

I put on 400lbs after remodeling the snout and have increased this further since. I haven't measured it yet because I'm not getting a stable setting.  I've got an 8:1 boat breaker and i'm pulling quite hard.

Title: Re: Rig Tension
Post by: JimC on February 20, 2008, 12:41:00 PM

I ran about 500lbs down the shrouds and 400lbs down the checks on Halo's stump rig without lowers. The caps came back to the mast so I set them on bend, not tension and didn't adjust them... She had to be beefed up a bit to cope with that loading - the orginal bulkhead layout for a single spreader tin rig wasn't good enough. Shroud/Check anchors were a U bolt (common to both) through wood gunwhales, obviously not an option on an all plastic boat, where I use unis over D rings.