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Old 04-02-2016, 17:56   #1
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Best way to fasten something to a Sailboat Mast

What is the best way to fasten something to a Sailboat Mast like mast steps, goose neck or cleats?

A boat mast is usually 1/8 inch thick and painted or anodized. Is very easy to drill and tap as its very soft.

Most mast makers like Z Spars, Selden and Sparcraft use Aluminum Blind Rivets because they work well.

1) All Aluminum Blind Rivets are the 1st choice
* No galvanic corrosion issues aluminum mast/ all aluminum rivets
* Very easy and fast to install
* Tool and rivets are cheap
* No real accuracy is needed
* Rivets are self-tightening and conforms to a sloppy hand drilled holes

2) Drill & Tap would be a 2nd choice as it takes more tools and skills
* Using Stainless Steel screws and bolts can have galvanic Corrosion issues
* Very detailed and slow process
* Need special and sometimes expensive tools
* Hand drills and hand taps are not very accurate and prone to angled or oval holes

3) Fine or Course threads for taped holes on a mast?
* Fine thread are preferred as they are 10% stronger and cover more surface area
* Fine threads do not tear the soft aluminum that boat masts are made of
* Fine threads give you more threads to hold onto the 1/8 inch thickness of a mast
* You will want to use Tef-Gel or Loctite Blue 242 on the threads
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Old 04-02-2016, 18:28   #2
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Re: Best way to fasten something to a Sailboat Mast

If your mast is only 1/8" thick I hope it's on a small boat.

The answer depends on what you're mounting and how much load it will bear and whether that load is sheer, compression or tension.

Small load, the benefits you list for Al rivets make them the choice.

Heavier loads go for SS or monel rivets or drill and tap.
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Old 04-02-2016, 18:31   #3
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Re: Best way to fasten something to a Sailboat Mast

Quote:
Originally Posted by ZipTie View Post
What is the best way to fasten something to a Sailboat Mast like mast steps, goose neck or cleats?

A boat mast is usually 1/8 inch thick and painted or anodized. Is very easy to drill and tap as its very soft.

Most mast makers like Z Spars, Selden and Sparcraft use Aluminum Blind Rivets because they work well.

1) All Aluminum Blind Rivets are the 1st choice
* No galvanic corrosion issues aluminum mast/ all aluminum rivets
* Very easy and fast to install
* Tool and rivets are cheap
* No real accuracy is needed
* Rivets are self-tightening and conforms to a sloppy hand drilled holes

2) Drill & Tap would be a 2nd choice as it takes more tools and skills
* Using Stainless Steel screws and bolts can have galvanic Corrosion issues
* Very detailed and slow process
* Need special and sometimes expensive tools
* Hand drills and hand taps are not very accurate and prone to angled or oval holes

3) Fine or Course threads for taped holes on a mast?
* Fine thread are preferred as they are 10% stronger and cover more surface area
* Fine threads do not tear the soft aluminum that boat masts are made of
* Fine threads give you more threads to hold onto the 1/8 inch thickness of a mast
* You will want to use Tef-Gel or Loctite Blue 242 on the threads
Plenty of misinformation here.

Use coarse threads. Much stronger than fine threads or aluminum pop rivets.
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Old 04-02-2016, 19:12   #4
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Re: Best way to fasten something to a Sailboat Mast

Which is stronger when tapped into a thin material for a small bolt. Two coarse threads or three fine threads?

TN, you always have a one line critique, but never an explanation or reasoning. Are we not worthy of being educated?

I have noticed in high load connections such as con rod caps and mains in engines are always fine thread.
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Old 04-02-2016, 19:33   #5
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Re: Best way to fasten something to a Sailboat Mast

Quote:
Originally Posted by Terra Nova View Post
Plenty of misinformation here.

Use coarse threads. Much stronger than fine threads or aluminum pop rivets.
+1

In low strength materials like aluminium, it's not the strength of the bolt that's so important, it is the likelihood of thread stripping. And coarse is the best solution for that.

There may be "more threads to hold on to", but coarse threads have more cross sectional area.
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Old 04-02-2016, 19:55   #6
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Re: Best way to fasten something to a Sailboat Mast

Quote:
Originally Posted by Terra Nova View Post
Plenty of misinformation here.

Use coarse threads. Much stronger than fine threads or aluminum pop rivets.
Quote:
Originally Posted by four winds View Post
...TN, you always have a one line critique, but never an explanation or reasoning. Are we not worthy of being educated?...
I explained that coarse threads were much stronger. What else do you want, egg in your beer?
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Old 04-02-2016, 20:19   #7
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Re: Best way to fasten something to a Sailboat Mast

To me it seems you stated course threads were stronger than fine threads. I didn't see an explanation as to why.

Stu did offer an explanation, however. Though that would apply in tension moreso than in sheer in my opinion. In a mast section fine threads may offer more resistance to loosening I would think.

Personally in the use stated here I would use those big honking aluminum rivets (high tensile aluminum) that require a 2-3 foot long tool to pop.
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Old 04-02-2016, 20:36   #8
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Re: Best way to fasten something to a Sailboat Mast

I have a Selden mast on my boat--65' tall, so it is a large one. Just asked Selden US about an eye for a whisker pole. The general manager gave me the part numbers and prices and said I would need a a pole eye, isolator pad, and rivet fasteners. I don't know the thickness of the mast---but Selden does, and they are suggesting rivets instead of coarse or fine thread screws. Am I missing something?
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Old 04-02-2016, 20:42   #9
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Re: Best way to fasten something to a Sailboat Mast

Fine threads are much-o easier to cross thread.
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Old 04-02-2016, 20:43   #10
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Re: Best way to fasten something to a Sailboat Mast

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Originally Posted by Moody46CC View Post
I have a Selden mast on my boat--65' tall, so it is a large one. Just asked Selden US about an eye for a whisker pole. The general manager gave me the part numbers and prices and said I would need a a pole eye, isolator pad, and rivet fasteners. I don't know the thickness of the mast---but Selden does, and they are suggesting rivets instead of coarse or fine thread screws. Am I missing something?
Only thing you missed is that the first post agrees with you. Rivets are the first choice.
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Old 04-02-2016, 20:47   #11
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Re: Best way to fasten something to a Sailboat Mast

I'd use rivets unless one of the two materials is too thick, otherwise screws. Not sure I'd use aluminium for anything structural though.Plenty of stainless rivets doing long term service in aluminium masts. Some use monel to reduce risk of galvanic corrosion.
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Old 04-02-2016, 21:00   #12
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Re: Best way to fasten something to a Sailboat Mast

There are structural aluminum rivets. They can be identified by having a domed head. Have set quite a few over the years but not on a sailboat.

High-Strength (HS) Rivets | Stanley Engineered Fastening
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Old 04-02-2016, 21:25   #13
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Re: Best way to fasten something to a Sailboat Mast

Quote:
Originally Posted by ZipTie View Post
What is the best way to fasten something to a Sailboat Mast like mast steps, goose neck or cleats?

A boat mast is usually 1/8 inch thick and painted or anodized. Is very easy to drill and tap as its very soft.

Most mast makers like Z Spars, Selden and Sparcraft use Aluminum Blind Rivets because they work well.

1) All Aluminum Blind Rivets are the 1st choice
* No galvanic corrosion issues aluminum mast/ all aluminum rivets
* Very easy and fast to install
* Tool and rivets are cheap
* No real accuracy is needed
* Rivets are self-tightening and conforms to a sloppy hand drilled holes

2) Drill & Tap would be a 2nd choice as it takes more tools and skills
* Using Stainless Steel screws and bolts can have galvanic Corrosion issues
* Very detailed and slow process
* Need special and sometimes expensive tools
* Hand drills and hand taps are not very accurate and prone to angled or oval holes

3) Fine or Course threads for taped holes on a mast?
* Fine thread are preferred as they are 10% stronger and cover more surface area
* Fine threads do not tear the soft aluminum that boat masts are made of
* Fine threads give you more threads to hold onto the 1/8 inch thickness of a mast
* You will want to use Tef-Gel or Loctite Blue 242 on the threads
Just out of curiousity... what possessed you to make this post?
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Old 04-02-2016, 21:34   #14
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Re: Best way to fasten something to a Sailboat Mast

Quote:
Originally Posted by four winds View Post
There are structural aluminum rivets. They can be identified by having a domed head. Have set quite a few over the years but not on a sailboat.

High-Strength (HS) Rivets | Stanley Engineered Fastening
I doubt that they're stronger than stainless. However, if the "thing" being attached to the mast isn't itself made of stainless steel, they might be ok.

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Old 04-02-2016, 21:42   #15
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Re: Best way to fasten something to a Sailboat Mast

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Originally Posted by four winds View Post
T

Personally in the use stated here I would use those big honking aluminum rivets (high tensile aluminum) that require a 2-3 foot long tool to pop.
Only way to go if you can get the rivets.

Fine threads are usually used in high tensile materials and the tolerences and fits need to be of higher quality to retain thread effectiveness.
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