dissimilar metals/mast gates

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sinnettc

sinnettc

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May 23, 2007
1,306
Catalina Capri 22 Albany, Oregon
I want to make a set of mast gates for my Capri 22. I've got a few options and I'd appreciate your thoughts on whether I'm liable to have corrosion/electrolysis issues:

Option 1: U channel zinc left over from stained glass project.

Option 2: U channel brass left over from stained glass project

Option 3: Sheet aluminum (?) flashing left over from roofing project.

What do you think, are any of these safe to use on an aluminum mast?

Thanks,
 
Hermit Scott

Hermit Scott

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Sep 25, 2008
2,288
C30 Event Horizon Port Aransas
I would definitely go with the aluminum. Are you in salt water?
I used unanodized aluminum for a small pedestal for my chart-plotter. I guess I had it on there for a year or so, it was crusty all over with aluminum oxide from the salt spray getting on it.
If the aluminum you use is anodized that would be best. I would try it even if it's unanodized and if you ever have a problem you could always pull them off sand them and clear coat them with a rattle can.
 
sinnettc

sinnettc

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May 23, 2007
1,306
Catalina Capri 22 Albany, Oregon
For the most part I'm on a freshwater lake. We spend maybe a week a year on salt water.
 
Hermit Scott

Hermit Scott

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Sep 25, 2008
2,288
C30 Event Horizon Port Aransas
sinnettc said:
For the most part I'm on a freshwater lake. We spend maybe a week a year on salt water.
Click to expand
I don't think you will have any problem with the aluminum you are going to use. I just put a bolt in the mainsail track yesterday for the first time because I was tired of the lugs falling out of the slot. I never thought of having gates so they will fall down further when they are put away.
Can you just drill and tap a hole for a bolt in the center of the track or is it necessary for the sail lugs to slide down past where they enter the mast?
 
sinnettc

sinnettc

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May 23, 2007
1,306
Catalina Capri 22 Albany, Oregon
I have a bolt in my track, just below where it narrows. We leave it in and go ahead and flake/cover the sail with the slugs above it. The only problem comes when I want to reef - I have to pull it out. The mast gates are my way around having to do that.

I have a bad feeling the aluminum flashing might actually be galvanized tin. Need to grab a magnet and check.
 
Clark

Clark

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Jun 30, 2004
886
Hunter 280 Lake Guntersville, AL
Hi Chris. I've seen aluminum flashing in the big box stores and it looks awefully thin and soft. A friend made one for his Cal 25 out of some door threshold/kickplate material - thinker and stronger aluminum but probably not anodized. Can you not locate a little sheet stainless to do the job?

Clark
Hunter 280
Capri 22 TR/FK
 
oldiesrocker2001

oldiesrocker2001

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Jun 8, 2004
350
Macgregor 21 Clinton, NJ
I agree with Clark. The flashing is far too soft. I had a new roof and a couple of alum gutters put on last summer. While the workmen were there I asked them to let me cut a length of one of the old gutters. While this may be strong enough, when they heard what I wanted it for they pulled a section of heavier flashing as used around the roof chimney. This is strong enough to hold it's shape but apparently can still be cut with metal shears (there will still be enough left to patch that charcoal grill tray).
As it turns out, I'm building mine tomorrow. A little trial and error will be involved, Im sure.. Don't forget to make an opening in the bottom just large enough to slide the slugs in "shotgun style" and file off rough edges.;)
 
Hermit Scott

Hermit Scott

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Sep 25, 2008
2,288
C30 Event Horizon Port Aransas
I missed that the aluminum is flashing. That is way too thin. I wouldn't rely on anything that can be cut with a pair of scissors to secure the sail to the mast. Try 1/8" at a minimum. 3/16" would be better.
 
rardiH36

rardiH36

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Jun 21, 2007
2,118
Hunter Cherubini 36_80-82 Sausalito / San Francisco Bay
1/8' aluminum has been fine for my DIY sail slug "gate" on the mast. Aluminum on aluminum shouldn't pose much a galvanic issue, particularly if the mast is painted and/or the aluminum is anodized. But one trick is to cover the mating side of the plate with electrical tape to keep the two metals isolated. I would be more concerned about the screws/bolts that will fasten the plate to the mast. Probably you will use Stainless Steel which will start to galvanic corode pretty quick when inserted in Al. Everytime that it removed/attached its a good idea to coat the screw with Lanacote or other anti-sieze compound.
 
Ross

Ross

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Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
You can get nylon machine thread screws that will serve perfectly for this job.
 
sinnettc

sinnettc

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May 23, 2007
1,306
Catalina Capri 22 Albany, Oregon
Thanks all. Still trying to decide what to do but I do know I'll skip the flashing. If I can track down some stainless sheet then that's what I'll use.
 
Hermit Scott

Hermit Scott

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Sep 25, 2008
2,288
C30 Event Horizon Port Aransas
sinnettc said:
Thanks all. Still trying to decide what to do but I do know I'll skip the flashing. If I can track down some stainless sheet then that's what I'll use.
Click to expand
Stainless can be very hard to machine. I tried to cut some SS in my large band saw and ripped the teeth on the blade up, I had to replace the blade. Drilling it can be very difficult as well. I would buy some aluminum plate. MUCH easier to machine and will match you mast. There is probably a specialty metal distributor in your town. You can buy small pieces at Lowes/homedepot but they are really kind of pricey when it comes to metal. You can get a 20' length for what they will charge for 1 or 2 feet. Look in the phone book under metal/specialty metal distributors.
 
oldiesrocker2001

oldiesrocker2001

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Jun 8, 2004
350
Macgregor 21 Clinton, NJ
While I was planning to build my slug gate in the early part of the weekend, on closer inspection, the flare was so small that I decided to try to hammer the flare shut and leave an opening near the bottom to feed the slugs in. It worked pretty well on the mast in the travel position. In the upright position, it needs tweaking. I'll try to close the feed opening a little at a time with my large slip-joint pliers each time I'm on the boat until it stops hanging up but still allows slugs to be removed and/or inserted. pretty soon, no more bungee cord to fiddle with! :dance:
 
Hermit Scott

Hermit Scott

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Sep 25, 2008
2,288
C30 Event Horizon Port Aransas
I bought this aluminum today. It's about 20"x2-1/2"x1/4"thick. It cost $6. I made the clutches tonight. I have SS plate, but I would never attempt to make anything like this out of it.
 

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sinnettc

sinnettc

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May 23, 2007
1,306
Catalina Capri 22 Albany, Oregon
1/4 inch seems a bit thick for mast gates but if I can find something 1/8' I bet it would work.

Are those home made halyard clutches?
 
Hermit Scott

Hermit Scott

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Sep 25, 2008
2,288
C30 Event Horizon Port Aransas
Yes, well they are clutches for two reefing lines and one line for the lazy jacks. They are coming along alright.
I swear I am compelled to make things.
 

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