Mast head crane

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paul manning
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Re: Mast head crane

Postby paul manning » Mon Sep 16, 2013 1:04 pm

You'd need to ask the measurer...
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paul manning
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Re: Mast head crane

Postby paul manning » Mon Sep 16, 2013 1:06 pm

Sergei - due to the casting process, sometimes you have to drill the hole out to get the pin to fit.
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chriswrightlaser
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Re: Mast head crane

Postby chriswrightlaser » Thu Oct 03, 2013 2:31 pm

Just had a play with the new mast crane and it's not that bad as expected reading the posts here, to cut off 10mm of rope now and again has to be done with the mast spilt or remove the crane from the mast, as the mast should be slit in half anyway now and again this is no problem.
1. Tie some strong .5 mm rope or whipping twine to the halyard,
2. remove the pulley.
3 with the mast split, pull the rope down very slowly with someone feeding the twine through.
4 put a knot in the new rope and bend it over 100mm from the knot, press the rope hard together to form a sharp curve that goes through the square hole in the crane.
5 tie the whipping rope at the new sharp curve with the 100mm tail with knot.
6 pull the curve through the square hole with the knot end towards the back of the mast, you can twist it around once it is through anyway.
7. put the pulley back in.
With regard to the knot it might work better with a small bobble between the knot and crane, could be a smll tube 5mm long? but it might kick up then and jam or rub on the rope coming up, anyone?
If the tube is too long it will get stuck in the mast or will not turn around when pulling the rope out from the middle of the mast, i feel that the tube would be the best for friction moving the knot away from the top but removal would be the main problem.
One solution would be to tie a 2mm vectran rope to make the knot with a 150mm tube covering the 4mm halyard between the crane and knot with the 2mm vectran end led through the trapeze hole with a small loop to keep it in place, as the tube is long enough to stop it kicking up against the upward rope it might work well. to remove broken halyard or just to move the knot you pull the rope by the trapeze point, once loose feed down to the end of the mast.

This has not been tried yet so I will post after a few sails in a few months time.

Will order a crane to have a look inside to see what will fit best. any other ways ?

Chris

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Re: Mast head crane

Postby chriswrightlaser » Fri Oct 11, 2013 2:32 pm

Having now played with a new crane head for a few hours now it works very well, its only when you have a good look inside that you get an idea of how it works.

The slot that grabs the knot acts like a small cleat, as the rope is pulled harder it gets crushed in the slot that is why its hard to remove as when you pull down the rope is still held in the tight slot. To remove the rope you need to push the rope out of the rear facing cleat or slot with a screwdriver after removing the pulley to gain access.

After many different type of rope tried in the crane the knot was well out of the way of the rope going upwards, the only way you might get problems with the new crane is incorrect fitting of the rope NO TAIL LEFT ON THE ROPE or the wrong rivets fitted.

The way the crane is riveted to the mast top might cause problems as if you use the rivets in the normal way, it would leave a tail in the path of the upcoming rope, I would say the rivets should not go through the crane but be a interference fit only in a blind hole or special rivets that only leave the smallest end in the square section at the front, anyone fitting a new crane might fit the rivets in the normal way might be in for some rope ware if they use the wrong rivets.

Happy with the new crane so far.
Chris

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Re: Mast head crane

Postby Serega » Fri Oct 11, 2013 3:09 pm

sounds like the bigger the challenge the happier you are Chris :wink:

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Re: Mast head crane

Postby chriswrightlaser » Fri Oct 11, 2013 4:10 pm

Serega wrote:sounds like the bigger the challenge the happier you are Chris :wink:


More the money part for me as 25 meters at £2. 50p a meter is no joke once it scrap, found the problem now, just tried some 3.7mm vectran in the mast and the knot landed in the wrong position in the slot but the knot excess facing forward ,this pushed onto the rope going up pushing the rope 2mm forward, they have used normal rivets and the ends are sharp and 3 to 5mm long, the rope is rubbing on the rivet and knot.

Now going to put a long round file in a drill and file away a few mm of rivets or use the extra long drills I have to do the job. also to use some sort of tube now to make sure of a clean gap.

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Re: Mast head crane

Postby chriswrightlaser » Fri Oct 11, 2013 4:51 pm

chriswrightlaser wrote:
Serega wrote:sounds like the bigger the challenge the happier you are Chris :wink:


More the money part for me as 25 meters at £2. 50p a meter is no joke once it scrap, found the problem now, just tried some 3.7mm vectran in the mast and the knot landed in the wrong position in the slot but the knot excess facing forward ,this pushed onto the rope going up pushing the rope 2mm forward, they have used normal rivets and the ends are sharp and 3 to 5mm long, the rope is rubbing on the rivet and knot.

Now going to put a long round file in a drill and file away a few mm of rivets or use the extra long drills I have to do the job. also to use some sort of tube now to make sure of a clean gap.


Changed my mind on that, going to put a stainless bolt through from inside with a shallow head, file curved to sit inside. file the thread of the bolt at the end to put a square end on the bolt, put some twine through the hole . put the twine down the bolt and wind around the thread back to the end of the bolt with the square head on it. pull the bolt through with the twine. put the nut on, grab the bolt with a pair of pliers. tighten the nut till home. cut the bolt flat to the nylock nut.

Is stainless steel bolts ok with carbon mast? does the bolt need coating with any product?

For info the rivet in the mast head is empty, no pin or pin head in the rivet in the supplied new mast.

Daniel Henderson
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Re: Mast head crane

Postby Daniel Henderson » Fri Oct 11, 2013 7:40 pm

Are these comment above not just confirming that the mast head crane is useless? It is even more depressing when you have a brand new 120 quid main halyard that is worn the whole way a lot it.
GBR557

chriswrightlaser
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Re: Mast head crane

Postby chriswrightlaser » Sat Oct 12, 2013 1:25 am

Boat 385 has worked out of the box from new with little or no maintenance required, The mast crane may be fitted wrong with the rivets too long, so is it the fitting or crane? could it be screwed in with self tappers?. it is only a problem if the knot lands wrong in the slot and pushes the rope against the rivets that are too long.
I can understand your pain with the cost of a good halyard at 25 meters lenth to replace, for the rest of us it requires a small bimble before use just in case we get the same as your post.

Is your £120 halyard 3.7mm like mine, the 4.1mm rope suppied by Ovington seems to work better as the knot jams further away from the slot, it worked ok till I tried the slightly smaller rope (3.7mm), the knot is closer to the slot with the thinner rope.

Chris

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Re: Mast head crane

Postby Serega » Sat Oct 12, 2013 9:07 am

ok, that's it. i am convinced now. i will stay away from upgrading to a new mast/boat for as long as i possibly can.

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Re: Mast head crane

Postby chriswrightlaser » Sat Oct 12, 2013 12:26 pm

Serega wrote:ok, that's it. i am convinced now. i will stay away from upgrading to a new mast/boat for as long as i possibly can.

That could be a long time then for you as the boats are made so well made, your boat is still new anyway, all they need to do is put the pulley 4mm higher and put the rope out through the side instead of down. or 3mm higher and make the v in the pully less of a v shape.
Not such a big job to replace the crane at any point or any time anyway but agree that if you are unlucky with the knot position it might cause a problem at the moment.

See you at the inlands
Chris

bambam
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Re: Mast head crane

Postby bambam » Sat Oct 12, 2013 12:28 pm

i just put the a old one back on, lasted a good few years (176)

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Re: Mast head crane

Postby chriswrightlaser » Sat Oct 12, 2013 12:49 pm

With the rope supplied by ovingtons 4.1 mm the knot gets jammed between the casting and the bottom of the sleeve 4mm further back right up against the carbon mast , this means the knot is pushed backward towards the back of the mast by the wedging / angle of the casting 20mm away from the top of the mast. when the 3.7 mm rope was used the knot moves between the casting and sleeve 4mm forward and 20mm up to the casting causing a problem if the knot lands wrong direction.
with a bit of luck all the new boats might be ok unless they change to a different halyard than suppied by ovington.

The 3.7mm rope can just slip between the sleeve and the casting right up to the casting 3mm below the top of the mast, as the sleeve is 4mm thick the knot must go 4mm further forward so can cause a problem?

This may be why Daniel had the problem with his very expensive halyard, you might think a thinner halyard would work better, but to use a thinner halyard means the knot lands in a different place? to use the 3.7mm halyard you need to put something on the rope to keep it 20mm away from the top below the sleeve edge or hope the knot lands in a good direction facing backwards.


Chris

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Re: Mast head crane

Postby Whits » Sat Oct 12, 2013 1:35 pm

Got to be honest... As this is causing so much debate and query it just doesn't sound like it is that good! How come we ended up with a different mast crane?

Cheers,
Andy

chriswrightlaser
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Re: Mast head crane

Postby chriswrightlaser » Sat Oct 12, 2013 1:56 pm

Their may be only 1 boat in 100 that may have a problem with the crane, the main problem might be the sailor that puts a new Halyard on just before the worlds and then has problems because it not standard ovington thickness then has problems getting the mainup / down before the race.
only Daniel that had great problems that I know with ware and friction, we know why now? as long as we know why it happened it can be avoided, I like the new crane but would like a mark two version with the tail coming out of the side. and slightly smaller/ shorter rivets.

Paul posted
"Chris - all the cranes have been of one design up until this new design coming into place around summer 2012.
The report from Selden confirms the reasons and thinking behind this design change. The key problem was the depth that the casting went into the carbon top section."

This tread may be a bitt OTT but if you want the class to grow its best to stop these little issues before they get ahold, its a shame a small inprovement could cause someone some hassle if they go for a no standard Halyard on the crane, The crane is ok but not as good as it could get.

Thank to Daniels post a few other sailors will now avoid any problems now, so goes to show how the forum can inprove the class and move forward. Thanks Daniel.

Chris


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