Jump to content

Diamond wire tension + fix


SEB YUKKA I
 Share

Recommended Posts

Hi everyone, I have noticed that the diamond wire on my mast is peeling off where the spreaders contact the mast. It has only just started happening but i don't think i should sail it as it is. it is quite an old boat so it is prob expected but i was wondering what i do to take the diamond wire off, i don't want to take it off then not be able to get it to the right tension again. it is taring the rivits out on one side because of the corosion it looks like. shoud i drill it out completly and put new rivits in or is that not nesercery????? also is there something you can put between the mast and the stainless to stop eletrilitic corousion???? any ideas or help would be great.

Thanks

seb

Link to comment
Share on other sites

Hi Seb,

Don't sail the boat until this is repaired or you risk bending or folding the mast, damaging the mainsail and personal injury.

At the bottom of the diamonds there should be S/S turnbuckles with numbers on them,(note the numbers and write them down as well as port and starboard, sometimes the settings are different) this will give you the correct tension when you put it back together.

Loosen the turnbuckles and remove the wire from the spreader ends, mark all parts port or starboard with texta so there's no confusion when re-assemabling. Drill out all rivets, remove and inspect. If the corrosion is to severe the all the diamond wire end fittings need to be moved around the mast or get some S/S 316 grade 2mm plate made into patches and rivet that onto your mast and place the fittings back in there original position. Also check your mast hound too!

If the spreader arm base is is loose or lifting off the mast you might need to drill extra holes in the base to make it a tight fit again.

I normally use 50mm white non skid tape cut to shape under all S/S fittings on aluminium and anti corrosive compound on the monel rivets. You can also use an ice cream container lid if you want.

Good luck on the repair and feel free to ask more questions if you are unsure what needs to be done.

Regards Steve.

Yukka I & Magic Time @ Trial Bay 07.

20070311_SY_0078.jpg

[This message has been edited by GRACELAND1216 (edited 26 March 2007).]

Link to comment
Share on other sites

hi Seb,

If you do as Steve says, you will save your mast from a major catastrophe.

What you describe is BAD , fix it before you go sailing again. Steve's advice on the fix is excellent, but make sure you do as he says and use an anti corrosion compound and the correct monel rivets, also it would pay to remove the mast base and check for internal corrosion.

Remember your boat is 20+ years old , and

it needs lots of TLC.

good Luck,

pete smile.gif

Link to comment
Share on other sites

Thanks guys

Well i havent taken off the wire yet but had a better look and have marked it all out , i think i'll have to move it down the mast a bit, how much is ok? does it have to be exactly in teh middle? what will i do with the holes in teh mast will they need welding. we have an aliminunim fabricator near by?????

thanks

seb

Link to comment
Share on other sites

hi Seb,

welding the mast will alter the temper of the metal, it is best to do as Steve says, move all the relevant fittings down by the same amount.If the corrosion is really bad, you may find it better to fit aluminiun pieces (sleeves) and pop rivet those in place, don't forget the anti-corrosion paste. If you need to, talk to Ross at the BCC, and ask his advice if you need the sleeve pieces, they are only short lengths of mast section, and they will strengthen the mast in the corroded area, if you use them ,

pete wink.gif

Link to comment
Share on other sites

Welding of an aluminium mast is an absolute no no. Pete's suggestion of aluminium mast sleeving is another option or you could use some S/S 316 grade 2mm plate to make reinforcing patches over the affected areas and place the fittings back in the original position. Again use a barrier between the S/S and aluminium and anti corrosive compound on the monel rivets.

Take some photos and send them to me and I can advise you from there, Rev has my email address.

Regards Steve.

[This message has been edited by GRACELAND1216 (edited 26 March 2007).]

Link to comment
Share on other sites

The fittings should not be movd verticaly, rather they should be move horizontally around the mast.

two reasons are, you have fresh alumium to rivet too, and the class rules allow for horizontal movement not vertical.

seal up the old holes with non skid tape and no one will be the wiser.

Link to comment
Share on other sites

hi Seb,

Hood is correct, rule 4.2 Spars, states positions are not to be altered.

As I see it the rules only apply to "class racing", so if you want to race, you will either have to "Sleeve" the corroded areas,or fix larger S/steel or Aluminium cover plates. I know this seems a big job, but rest assured it is really an "everyday' fix for us. (We have the facilities and required parts on hand.)

I am sure that Steve will steer you in the best,and easiest/safest method.

Good luck,

pete smile.gif

PS.

As Hood says, moving the upper and lower tangs around the mast,and re-drilling extra holes in the spreader base maybe all that you have to do, don't forget the anti-corrosion stuff.

pete biggrin.gif

[This message has been edited by xmatelot (edited 26 March 2007).]

[This message has been edited by xmatelot (edited 26 March 2007).]

Link to comment
Share on other sites

hi Seb,

I think that if you are just going to move your spreader base down, you may not have to move the upper and lower tangs.

Slacken your diamond wire adjusters off as much as you can, and then if you drill the pop rivets out of the spreader base, you should be able to slide the spreader arms and base up or down to a new position.

This may be the best answer for you.

If it is O/K them put anti corrsion stuff under the base, and re-drll and rivet. Then you can put rivets and/or patches where it used to be. As Martin say's , this may be the solution, rules or not.

Good Luck.

pete wink.gif

Link to comment
Share on other sites

  • 1 month later...

These critical area's of the mast definitely need resleeving of some sort. Whether you use T6061 T6 (available from some good ally resellers), mast section (similar, if not the same grade & temper) or stainless 50 x 3mm Flat bar, definitely use an isolating compound.

We've used Duralac for years, after pulling fittings/rigging off big boats that have lived in a marine environment for 20 years or more and found little (very little) or NO corrosion, i don't think there's a better endorsement.

You could use Sikaflex (also brilliant stuff, just not for this), but it will deteriorate over time due to the fairly rapid expansion & contraction that happens with ally in the sun.

Regards,

Leroy wink.gif

Link to comment
Share on other sites

6061 T6 is as common as dogs bal....err hind leg, masts are made out 6061 T6 and because of this they do corrode fairly well as one of the main alloying metals of the 6XXX series is magnesium. When you go to any metal merchant and ask for aluminium chances are you will be handed 6061 T6 unless you specially ask for another alloy in which case he would have to order it in. If you go with the sleeving idea get the fabricator to shape it for you as it is a bitch to take nice even curves around your mast. When the time comes to fit it to the mast use either monel or stainless steel rivets placed in a random pattern and have a bed of silastic between the sleeve and the mast (both nicely cleaned with emery cloth NOT steel wool)Use lots of worm drive clamps and let the silastic ooze out and start riveting from one side and work your way around the mast. The Silastic should be of the NON acetic acid curing type. If you have done everything right your mast will be stronger than new.

regards, Harry

Link to comment
Share on other sites

Sorry to correct a couple of things... Having bought an average of 70 ton per year for the last 4 years, I can reliably advise that most (90%) of all off the shelf alloy sections and solids retailed are 6060 or 6063 T5 not T6. This is because T6 is difficult to machine as it takes the edge off any tooling extremely fast.

Generally (90%) of 6061 which a smaller part of the retail market is also sold as T5.

T6 (for 6060, 6063 and 6061) is usually a special order for the Tempering ("ageing") as this is a heat & time critical process that must be done in accordance with Australian & International Standards.

The rolling of alloy stock to suit the shape of the mast has potential to weaken the alloy but would be obviated by utilising already anodised off-cut wall sections that are available thru Brisbane Cat Centre.

I'd also suggest that the fixing pattern NOT be random, but be diagonally opposed with some attention to the critical load paths. Again Ross @ BCC will probably give you a diagram to work with. In fact, if you give Ross the size and position (side wall, front or whatever) he will probably cut and pre-drill for you....

Hope this helps with the repair.

Regards,

Leroy wink.gif

[This message has been edited by Leapin Leroy (edited 10 May 2007).]

Link to comment
Share on other sites

Typically magnesium represents only 0.8-1.2% by weight of the extrusion otherwise it can't be classified as 6061... or aluminium, per se.... Further, the additional substances allowed in the metallurgical make up of Aluminium amount to an average of 2.5% by weight of the extrusion. Some of these like Iron, Zinc, Titanium & Manganese have maximum values of; 0.7%, 0.25%, 0.15% & 0.15% respectively. (Iron, can you believe that?).

The difference between T4/5 and T6 is significant when considering the Ultimate Tensile Strength. T4/5 has a minimum of 180 MPa whereas T6 has a range of 260-310 MPa.

With 6060 or 6063 these values typically change to 160MPa (Min.) for T4/5 and 245Mpa for T6.

All that and we haven't even considered 7xxx series alloys & T7451 or T7651 Tempers... LOL.

Hope this is enough to put you all to sleep...

Regards,

Leroy wink.gif

[This message has been edited by Leapin Leroy (edited 10 May 2007).]

Link to comment
Share on other sites

Ok i finally got back on the net.... I havent done teh repair yet. Thanks sooo much for all this info, i was really stabbing in teh dark when i first thought of repairing it.

You guys seem to really know your chemistry.

Anyway when i get a chance ill pull teh mast apart and try to get this repair cranking.

I have a guy who makes my moto x exaust systems who can prob get the right aluminium and roll it up, but if not who is this person who could get teh right peice drilled and ready for me?

ok thanks again guys

Regards

seb

Link to comment
Share on other sites

Seb,

Give Ross a call @ Brisbane Catamaran Centre, (07) 3271-4944.

Regards,

Leroy wink.gif

P.S. Don't forget the Duralac, be generous with it and clean up quickly. Corrosion results from the differences in the metallurgy between alloy & stainless steel fixings (rivets etc). These two things are about as far apart on the "Nobility of Metals Table" as you can get so when you add salt (Sodium in all it's glory), you end up with one or both galvanic/electrolytic corrosion....

Here endeth the lesson, LOL. wink.gif

[This message has been edited by Leapin Leroy (edited 10 May 2007).]

Link to comment
Share on other sites

  • 2 weeks later...
  • 2 months later...

OK well i know its been a long time in the coming but i have finally pulled apart the mast and cleaned it up, i have been really busy with exams and that sort of thing so the boat has been a bit neglected over the winter, but now the weather is warming i'm getting really pumped about this season....so.... There is a lot of corrosion on the mast but is not tooo widely spread, the peice that was on there (as u know) was about 2 inches by about 6 or so wraped around the front of the mast.... well it looks as though it has been drilled b4 because there are more rivits on 1 side..... there is a lot of corosion on the front and a hole from where the rivets were, (the 2 rivet holes have opened to one) but it hasn't corroded back up to far. and there is also a bit of damage where the side of the bracket attached. we've cleaned it up and now the question is how big should the sleeve be that we put over? obviously to small and it will fold up, but i suppose if its too big it may be affected by the bend in the mast.???? any ideas????

thanks guys,

regards

seb

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...