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an ounce of prevention...
http://www.hobie.com/au/en/forums/viewtopic.php?f=75&t=11520		 Page 1 of 2
Author:  Philip1el [ Wed Jan 07, 2009 12:58 am ]
Post subject:  an ounce of prevention...
Learning as I go, most of my failures have been due to a disproportionate amount of time spent sailing in relation to time spent CHECKING stuff. I had in the past noticed a slight gap (1-2mm) on one side of the mast receiver where its bolted to the hull, it wasnt lying flush....but the mast was locking in and the furler drum not riding on the collar, mast looked straight. I didnt want to fiddle with it. Now I have removed it and noticed the drilled hole in the base where it bolts into the hull is damaged, its egged out. Had I adjusted the V frame and checked the securing nut this would not, I believe, have been a problem. Also, I remember a post ages ago relating to this but I paid no attention to it!

This is not a design defect, its lack of maintenance, worth looking down there and making sure everythings seated true.
Author:  Pirate [ Wed Jan 07, 2009 1:32 am ]
Post subject: 
How can you be sure it wasn't a problem at manufacture?..Pirate
Author:  Philip1el [ Wed Jan 07, 2009 2:13 am ]
Post subject: 
because a simple adjustment on the v frame would allow the base to seat evenly inside the hull and not bear against the bolt on one side.
Author:  Pirate [ Wed Jan 07, 2009 3:20 am ]
Post subject: 
Fair enough Phil. I wonder if the dealers do a pre delivery check before it goes out to us consumers?..Pirate
Author:  Tom Ray [ Wed Jan 07, 2009 5:06 am ]
Post subject: 
Now that I know how it works, I check v-brace adjustment before delivering a new boat at the dealership.

My wife's boat came with the brace not quite right, and the furling drum was rubbing when furling and unfurling the sail. Matt Miller told me what was wrong and how to fix it. It is easy to adjust with the mast in place because the movement and change in clearance is apparent when you twist the turnbuckles.

The V-brace is another place where unlike metals plus salt water has resulted in some corrosion, despite my efforts to prevent it. I coated all the parts with Boeshield T-9, and I rinse out the V-braces and the insides of the hulls when there has been salt water splashing around in there.
Author:  Pirate [ Wed Jan 07, 2009 1:47 pm ]
Post subject: 
Tom Ray wrote:
Now that I know how it works, I check v-brace adjustment before delivering a new boat at the dealership.

My wife's boat came with the brace not quite right, and the furling drum was rubbing when furling and unfurling the sail. Matt Miller told me what was wrong and how to fix it. It is easy to adjust with the mast in place because the movement and change in clearance is apparent when you twist the turnbuckles.

The V-brace is another place where unlike metals plus salt water has resulted in some corrosion, despite my efforts to prevent it. I coated all the parts with Boeshield T-9, and I rinse out the V-braces and the insides of the hulls when there has been salt water splashing around in there.


It might be well for Hobie to alert their dealers to do this check as a pre-delivery must.
Also I question Hobie's continued dis-similar metals usage. Every course I have attended be it nautical or aeronautical stresses the problems associated here and the disasters that can result. Why do they persist?.....Pirate
Author:  mmiller [ Wed Jan 07, 2009 2:43 pm ]
Post subject: 
No sure what is dis-similar in the "V" brace. That assembly is entirely stainless as far as I recall. Not all stainless parts are the same grade though. Some parts are fabricated and some purchased.

We have to use dis-similar materials of all kinds to create our products. Plastics of a few kinds. Some roto mold, others injection mold, some stiff and some flexible. Metals are no different. Stainless for strength, aluminum for weight / strength and extruding, high grade brass for molded-in parts. All the materials have their place.

It is all a balance of function / weight / performance / cost etc.
Author:  mickeymouse [ Wed Jan 07, 2009 3:10 pm ]
Post subject: 
mmiller wrote:
No sure what is dis-similar in the "V" brace. That assembly is entirely stainless as far as I recall. Not all stainless parts are the same grade though. Some parts are fabricated and some purchased.

We have to use dis-similar materials of all kinds to create our products. Plastics of a few kinds. Some roto mold, others injection mold, some stiff and some flexible. Metals are no different. Stainless for strength, aluminum for weight / strength and extruding, high grade brass for molded-in parts. All the materials have their place.

It is all a balance of function / weight / performance / cost etc.


Not my area of expertise - however here is a brief quote and a link.
There is heaps of info on the net re this and a simple google will provide heaps of info.
Quote:
Galvanic corrosion, often misnamed "electrolysis," is one common form of corrosion in marine environments. It occurs when two (or more) dissimilar metals

http://www.ocean.udel.edu/seagrant/publ ... osion.html

Mickey
Author:  mickeymouse [ Wed Jan 07, 2009 3:23 pm ]
Post subject: 
Tom Ray wrote:
Now that I know how it works, I check v-brace adjustment before delivering a new boat at the dealership.

My wife's boat came with the brace not quite right, and the furling drum was rubbing when furling and unfurling the sail. Matt Miller told me what was wrong and how to fix it. It is easy to adjust with the mast in place because the movement and change in clearance is apparent when you twist the turnbuckles.

The V-brace is another place where unlike metals plus salt water has resulted in some corrosion, despite my efforts to prevent it. I coated all the parts with Boeshield T-9, and I rinse out the V-braces and the insides of the hulls when there has been salt water splashing around in there.


Tom

Where are the instructions on how to adjust the V brace?
Or is the above all the info necessary?
As far as I know mine is OK, however I did notice recently that the lock nut on one side is very loose and the turnbuckle on that side is easily turned by hand whilst the other side is tight. Consequently I tightened up the loose side somewhat and also the lock nut.

Mickey
Author:  Tom Ray [ Wed Jan 07, 2009 5:00 pm ]
Post subject: 
Matt, the v-braces on our boats have bronze pieces.

Pirate, all the boats I have seen, and the other lines for which we are dealers, use dissimilar metals for the reasons Matt stated. There's all kinds of stainless hardware on almost every aluminum mast and boom in the world, and it's a problem. However, the benefits of using those materials outweigh the problems.

Mickey, Matt sent me instructions on adjusting the v-brace. Just put in the mast, note the clearance on both sides between the furling line drum and the collar that contains the bearings.

Loosen the lock nuts away from the turnbuckle body, and turn both of the turnbuckles, watching what happens to the drum clearance. You'll find you can raise or lower the mast by just turning the turnbuckles one direction or the other.

Basically, you're using the turnbuckles to spread or compress the boat vertically, pulling the mast base up or pushing it down. When it has adequate clearance and it's even on both sides, tighten the locking nuts against the turnbuckle body. I think ours have about 1/8" clearance, maybe a little less. If you set it too high, the latch won't engage and the mast could pop out. If you set it too low, the drum will rub against the collar.
Author:  mickeymouse [ Wed Jan 07, 2009 5:05 pm ]
Post subject: 
Tom Ray wrote:
Mickey, Matt sent me instructions on adjusting the v-brace. Just put in the mast, note the clearance on both sides between the furling line drum and the collar that contains the bearings.

Loosen the lock nuts away from the turnbuckle body, and turn both of the turnbuckles, watching what happens to the drum clearance. You'll find you can raise or lower the mast by just turning the turnbuckles one direction or the other.

Basically, you're using the turnbuckles to spread or compress the boat vertically, pulling the mast base up or pushing it down. When it has adequate clearance and it's even on both sides, tighten the locking nuts against the turnbuckle body. I think ours have about 1/8" clearance, maybe a little less. If you set it too high, the latch won't engage and the mast could pop out. If you set it too low, the drum will rub against the collar.


Gotcha :wink:
Thanks for the clear explanation 8) :)
Mickey
Author:  Pirate [ Thu Jan 08, 2009 4:01 am ]
Post subject: 
mmiller wrote:
No sure what is dis-similar in the "V" brace. That assembly is entirely stainless as far as I recall. Not all stainless parts are the same grade though. Some parts are fabricated and some purchased.

We have to use dis-similar materials of all kinds to create our products. Plastics of a few kinds. Some roto mold, others injection mold, some stiff and some flexible. Metals are no different. Stainless for strength, aluminum for weight / strength and extruding, high grade brass for molded-in parts. All the materials have their place.

It is all a balance of function / weight / performance / cost etc.


Hi Matt, You are missing the point here. Not talking about dis-similar material...I am referring to dis-similar metals. Aluminium doesn't stand a chance if it is direct contact with steel. Electrolosis sets in and eats the aluminium, especially fast in a salt water environment. It is essential that dis-similar metals are kept apart wherever possible and not allowed to contact one another. Having said that I am also not aware of the different metals are using for the mast brace, but if it isn't right, they won't last long in salt water so I expect Hobie have got it right...Pirate
Author:  mmiller [ Thu Jan 08, 2009 11:01 am ]
Post subject: 
We do know about dis-similar metals. My comments about dis-similar materials were more broad stroke and included the use of dis-similar metals in our products. In example, Hobie Cat masts are highly stressed and use combinations of aluminum extrusions, castings, stainless fittings and stainless rivets. It is industry standard to use stainless rivets in aluminum. Aluminum rivets do not have the needed shear strength. The aluminum is anodized and we use anti corrosive tape under stainless fittings where possible to limit the contact. Many boats built back in the late 60s and 70's are still sailing today, so the corrosion is an issue, but it takes a very long time.

I had forgotten about the brass adjusters in the "V" brace assembly. The issue there is the ability to adjust them. Stainless on stainless threads cause galling and seize, so we use high grade brass for least corrosion and best adjust-ability. There is little or no reaction between this brass and the stainless. Many fittings molded-in to the hulls are brass for the same reason. The brass also conducts heat better allowing the plastics to melt and flow around the fittings during the production process. The brass will discolor, but like copper roofing, this is a corrosion resistant layer after that.
Author:  Chekika [ Thu Jan 08, 2009 1:19 pm ]
Post subject: 
This topic about corrosion on the AI is very interesting. I went to Answers.com and looked up "Galvanic corrosion." The full discussion is at http://www.answers.com/topic/galvanic-corrosion-1#Galvanic_series

This is my paraphrasing of the statement: [i]Dissimilar metals in seawater form an electric cell when in contact. Galvanic corrosion eats away the less “nobleâ€
Author:  chrisj [ Thu Jan 08, 2009 2:21 pm ]
Post subject: 
Chekika wrote:

Quote:
why doesn’t Hobie install a sacrificial zinc strip to protect the aluminum pieces?


Keith,

I have no expertise in this matter whatsoever, but are you sure that is galvanic corrosion? The area of contact between the stainless steel pin and the aka seems to be the least corroded in the photo. My (amateur) instinct would be to sand the area back, treat the corrosion and repaint.

Chris
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