Replacing rivets w. bolts in the rig

mange

Member
Hi,
I need to replace all rivets on the gooseneck and and a few on the boom (fairlead, block loops) - they are loose either by corrosion or high stress. After removing some rivets I can see there is some corrosion in the alu tubes and I think through-bolting is the solution, but with what dimension?
I figure an M4 with a nylon locker nut is enough?

Then we have the problem with corrosion. I believe that when people talk about s/s rivets, they mean "monel"-rivets? They are less harmful for the aluminium and should be used on alu.rigs.
But my bolts are not monel - they are higher grade ss "A4".
Will this accelerate the corrosion so next time I'll have to replace M5 and after that M6 and so on...
 
mange said:
I think through-bolting is the solution, but with what dimension?
I figure an M4 with a nylon locker nut is enough?
..."monel"-rivets"... ..."A4". ...
Hi mange,
M4 with a washer and nylon locker nut, will work for the Nylon-fairlead for the Outhaul (length of the bolt ~ 15mm / or 20 mm). For the metall eyes for the blocks and for the Vang-key support, I would prefer M5 x 10 (or 15 mm works also). For the gooseneck attachment at the mast, I'm not sure. The rivets at the masts for my Laser seem to be bigger than "Monel" Type 4,8x10 at the gooseneck-attachement. Maybe Scott can say this.

All I know: "A4" is AISI-Type "316". Dave Kirkpatrick, a former manager of teamvanguard and memner of this forum, in summer 2004 adviced me to use Screws AISI Type "317" (is better than A4), but not to get here. I use A4 often. A4 says: that it is "high-quality-steel" and it has very-very low oxidation if used in saltwater. A2 (also a stainless steel) will have very low oxidation in sweetwater but probably some in saltwater aft a time.

If you have to open the plugs at the boom, mange, be careful with that. they are very smoth and can be destroyed easly. In spring, we´ve discussed that already somewhere here at the forum. Search for that thread, before you start to damage much the plugs and have to send some extra money to buy new ones.
Ciao
LooserLu
 
Unfortunatly I am in the US. I call the appropriate fasteners #10 machine screws made of 18-8 stainless. The Nuts are nylon insert lock nuts.
My usual gooseneck trick has been to use a long stick to insert the machine screw from the inside. I use a long screw and poke it out through the mast and through the fitting. Then I hold the bolt with Vice Grips ( a locking plier tool) and spin the nuts on from the outside. Then I cut off the extra machine screw and file it smooth.

If there is a corrosion problem..
1. I hope it is mild. Corrosion at the gooseneck often leads to broken masts. Usually the break comes in light wind when the vang is off becuase the cracks are aft and under compression except in light vangless sailing.
2. It is probably a great idea to paint the area inside and out with whatever the locals use on their keelboat mast fittings.
Zinc Chromate primer is what I use but I am not near salt water and my technology for that stuff is 20 years out of date.

Note: DO NOT through bolt the mainsheet block such that the nuts are on top of the boom. I am not realy certain why that breaks booms but every one I ever saw through bolted was broken when I saw it. Perhaps it has to do with putting the load on the wrong side of the structure or maybe the lower side of the bolt cuts the bottom. All I know is I have never seen a boom broken with bolts just through the bottom and I have seen at least ten broken when the bolts were all the way out the top.

Good luck
 
Through bolting the gooseneck as gouvernail suggests would work but I wouldn't try drilling all the way through the mast as the additional holes would cause failure for sure. The best anti-corrosion product out there is Lanocote (made from natural Lanolin) by Forespar, smear some on the rivets/screws as well as mast and works everytime (only problem is your hands end up smelling like a Kiwi sheep farmer ewww)...
 
Hi again,
two questions. Would you rivet the gooseneck-support again to the mast or would you take bolts?

The 2 lower mast-sections I have (one for the Radial and one for the standard), the gooseneck-supports are not loose and I never have seen such loose ones here (only sometimes bended old gooseneckparts)).

If you rivet them, is diameter 4.8 right or is this to small?

By side:
With "trough bolting" I had a problem in translation (same like the Americans say "frankfurter" to a saussage that the citizens of Frankfurt at the river Main call "Wiener-Würstchen" (="Saussage of Vienna" in 1:1 English language)) ;). Thanks, now I now what it means. I never would "through bolt" the tubes of the rigg. Thats why I wrote above, the bolts may suit with a length with 10 milli-Meter or 15 or 20 milli-Meter (but not 60 ore more milli-Meter). From the side of the engineer I can tell you a looong story about that, but I guess it will bore you....;)
And: AISI/ASI 316 is an US-Standard, not a European-standard. Aft Dave told me to use that "Type 317"-Screws for the deck, I ran to several local shops that offer steel-parts. No one could say me what sort "Type 317"-Screws are... I asked a friend that is machinery-engineer at Volkswagen in Wolfsburg/GER. He told me there are millions of different srews but he never heard about "Type 317".... Half a year later, I was designing the steel-disc for the maststep (Scott, I think you remember that thread at the forum). In a Thyssen-book "sorts of steel for designing/construction" (I'm civil-engineer) I found, by luck, what "Type 316" is: The US-name-equivalent for that what in Europe is called "A4".... Alloy-Steel with Ferro-Chrome-Nickel-Molybdaen in it. A2 is steel with Ferro-Chome-Nickel in it and "Monel" is an alloy with Nickel and Copper in it, that is very durable in saltwater....

I more prefer the "alloy" of lime, crushed ice, brown-sugar and Pitú, better known as "Caipirinha"... :)
Cheers
LooserLu
 
Thanks for sharing your tricks with me. Heard the trick with an long screw inserted from the inside from my local dingy-shop (I think Scott misunderstood gouvernail) - a simple clothes-peg on a long stick.

I've already dismounted the boom end plugs, and yes LooserLu, it was tricky. After struggling with the front plug, I decided to buy a new one - the gooseneck pin hole was wearn/big anyway. The other end was even more stuck, but I managed to bang with a long steel rod from inside.

I think I'll be using M4 with washers all over, the pull-out strength is probably higher than a 4,8 rivet anyway. Maybe M5 in the gooseneck.
Anyway, I spent some thoughts regarding the A4 quality (here in Sweden we call it "acid proof") and galvanic corrosion with aluminium: Maybe it doesnt matter since the gooseneck and vang fixation etc. is in stainless steel, as long as there is a galvanic contact, there will be corrosion. When I dismounted the boom vang plate there was clearly corrosion under this plate all over the contact surface.
TheBoathouse suggest Lanocote - I'll try find something like this and also be careful to wash saltwater away after use.

One last question about through-bolting though: How do I solve the end bolt in the outhaul fairlead?
I should also fixate the end plug. Someone wrote "bolt the fairlead and use additional alu-rivet for the end plug" - suppose that means I have to drill another hole in the boom+end plug?
(No problem for me - just thinking about the class rules)
 
The rivet dia used on the spars is the same for all fittings - in the US it's 3/16" dia.

The gooseneck fitting really only needs to have two bolts - one in each side of the middle hole. Save some time and re-rivet the rest if they are loose.

On the outhaul fitting you can use one long bolt for the inboard end and exit out thru the bottom of the boom thru the aft hole of the eye strap that holds the mainsheet block.
 
To quote LooserLu - we overlaped our replies,

>>Would you rivet the gooseneck-support again to the mast or would you >>take bolts?

Depends on the conditions/diameter of the holes. If possible, I'll use rivets. If the holes are bigger due to corrosion or being careless when drilling out, then I will use bolts.
You should be careful when you drill loose rivets - its very easy to have the rivet rotating together with the drill - this will destroy the chance to re-rivet in the same hole.
For estetical reasons I will chose to have the same in the gooseneck.

A comment on "trough-bolt" - I meant bolting through only one wall in the tube, the reasons to use long screws is 1) to be able to get a grip on the screw with your clothes-peg (on a long stick) when you insert it from the inside and finally 2) get a grip on the screw end when you tighten the nut.
When the nut is tightened, cut and grind the screw.
So 15 or 20 mm is too short - I use 40mm - they can't be longer than the inside diameter of the boom.

Impressive knowledge in alloys - also heard that ASI-316 equals A4. Please note however that monel also has good behaviour regarding galvanic corrosion together with aluminium.

/Magnus
 
49208 said:
On the outhaul fitting you can use one long bolt for the inboard end and exit out thru the bottom of the boom thru the aft hole of the eye strap that holds the mainsheet block.

Nice solution, thanks for the tip!
/Magnus
 
Hi Guy's,
Somethings to think about regarding electrolysis (galvanic corrosion or white rust)... It is the two dis-similiar metals, the ferrous stainless & nonferrous aluminium are the root cause. Using 316 or 317 grade stainless steel rivets or bolts will not stop it. When the two metals and saltwater meet. Saltwater with it's high conductivity properties greatly accellerates it.
Some thoughts on preventing it or slowing it down at least are using anti-oxidant coatings. Electricians use a product called Oxyguard and I am sure there are a bunch of others out there that will work... Also perhaps using a product called Coppercoat that is a spray on gasket material sold in autoparts stores. By using a barrier of copper I think it would greatly arrest the process. Any type of barrier will help, very thin plastic shims, the lanolin that Scott mentioned will also help do the same thing which is provide a barrier between the two dis-similiar metals. Lou do you have more thought that might help the issue?
Best regards for now,
Fishingmickey
150087/181157
 
Hi Fishingmickey,
I agree with you on all points except the Coppercoat thing you mentioned.
You are fully right about the galvanic process, but using coppercoat will probably have the opposite effect on aluminium. I'm not familiar with coppercoat but suppose it some kind of paint/spray with copper in it.

For instance, I paint my powerboat (with outboard engine) with an copper based paint to stop organic growth (like barnacles) on the hull below waterline. This paint you should NOT use on the outboard parts which are under waterline - same for sterndrive's. The reason is the copperbased paint will start galvanic corrosion on the aluminium engine parts. I've know a guy who painted his alu. propeller - he had to buy a new one

Without digging too far in this matter, you should use a metal with less "galvanic potential" than aluminium - e.g zinc - outboard engines/stern drives has zinc anodes). But using zinc anodes on the boom and spar on a Laser is definitly going too far.... the Laser is-as-is, it has st.steel in galvanic contact with alu. The best thing to do is use lanolin or similar product to slow the process and very important: wash with fresh water to get rid of the salt.
My rig will probably last for many years anyway - I hope...

Regards
Magnus
 
fishingmickey said:
... Lou do you have more thought that might help the issue?
Howdy, I think magnus is right, but of course I looked a bit around for that, here in GER.
An equivalent to Scott’s Lanocote, that I would get in GER:
Le Tonkinois
http://www.letonkinois.de/images/e_text.htm

The civil-engineer Lu would try to test this for his tiny bridges (depends of the result of the tests and the price of the product) [and no, I was not one of the designers of that bridge that dropped down under constuction in Spain some hours before...] :
MC-Mioaluminum Primer 2.8 (attention: it‘s very toxic during the painting) :
http://www.wassercoatings.com/data/MC-MioAluminumPrimer8.5x11.pdf

Regarding to magnus´s words I résumé, the gov already told us how to do (
"Zinc Chromate primer"), but Scott's Lanocote seems to be the less toxic stuff.


magnus, bolts of 40mm length, and the way you described to use them is possible, from my view, right. But, they cost a bit more and I have help to fix the short bolts I use. The shorter lenghtened bolts work, but help to fix them is needed, of course. :)
Ciao
LooserLu
 
Hi,

I tape a box end wrench onto the stick. Then lightly tape the bolt to the wrench. Insert, and use the wrench to hold the bolt til tightened.

We've discussed the galvanic thing before, but "search" doesn't seem to be working for me.

The SS fitting is just as bad as the river or bolt. See pic. I'd separate the two with plastic packing tape, cut after installation to extend 1/4 inch outside the fitting. The tape will last if you store it out of the sun.

You can also end for end the mast bottom or top, when the corrosion or wear gets scary bad, and make them last longer. When I reverse the top, I rivet the collar on with a rivet well below the joint, not in the original hole in the collar. The original location is just too ridiculous for me to repoduce, but this may be illegal?

Also, make sure you have a boom sleeve before you put it all back together. And you can't reverse a radial bottom, due to the sleeve location, unless the sleeve slides when all the rivets are out. Has anyone tried this?

Also, if you sail exclusively in freshwater, don't bother with any of this!

Al Russell 182797

Al
 

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vtgent49 said:
".. unless the sleeve slides when all the rivets are out. Has anyone tried this?"

Al

Yes Al, I had the sleeve out of my boom these days - its no problem to slide it out at all after removing of rivets.

The sleeve is a 45mm dia. alu.tube 600 mm long, simply a standard measure and not so mysterious "builder supplied". Its actually a quite loose fit into the boom - inner diameter of the boom is aprox. 47,5 mm
It was located with its center over the vang fix plate.

Since my boom where slightly bent aft of the sleeve, I first tried to carefully bend the boom back a bit with some success. Its not straight now but better.
Then I placed/slided the sleeve back again, now with its center over the bended place. In this way the sleeve reaches the front main sheet block and the vang plate. The sleeve is now bolted (main block and vang points) at this new place.
I checked with the rules - the sleeve can be max 900 mm long and max 1200 (something) aft of boom front.
Ideally, I should have the max lengt 900mm sleeve. I have now created a new weak spot on my boom over the vang fix plate where the sleeve had its center before.
But its considerable stronger on the bended spot...
I don't worry too much - if it bends again I'll find my self back to point zero, if it brakes then I have to buy a new...

Regards
Magnus
 

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