Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 04-02-2016, 23:15   #16
Senior Cruiser
 
44'cruisingcat's Avatar

Cruisers Forum Supporter

Join Date: Sep 2006
Posts: 7,454
Images: 69
Re: Best way to fasten something to a Sailboat Mast

When I put my rig together I used monel rivets on anything with serious load on it. Except the gooseneck, which has 8 drilled and tapped screws.


A pneumatic rivet gun makes life much easier.
__________________

__________________
"You CANNOT be serious!"


John McEnroe
44'cruisingcat is offline   Reply With Quote
Old 04-02-2016, 23:30   #17
Registered User
 
four winds's Avatar

Join Date: Oct 2010
Location: Wandering the US Gulf Coast
Boat: 78 Pearson323 Four Winds
Posts: 2,138
Re: Best way to fasten something to a Sailboat Mast

Here's what the blind side of a sealed high strength aluminum rivet looks like after installation. Not a typical rivet. To me this would be the best material and design to be smashed up against the inside of an aluminum mast.

Edit to add,...... 44, this post wasn't in response to your mention of monel. Love that material in my 40 year old trouble free fuel tank.

Probably look at my gooseneck tomorrow. Recall it's bolted and curious how thick is the mast. I've been assuming this thread was about mast steps only for some reason.
Attached Thumbnails
Click image for larger version

Name:	tmp_27571-tvd-520-1046879268.jpg
Views:	124
Size:	56.9 KB
ID:	118365  
__________________

__________________
Life begins at the waters edge.
four winds is online now   Reply With Quote
Old 04-02-2016, 23:32   #18
Registered User
 
Terra Nova's Avatar

Join Date: Apr 2007
Location: Marina del Rey, California
Boat: Freya 39 cutter- Terra Nova
Posts: 3,645
Re: Best way to fasten something to a Sailboat Mast

What do think would shear quicker, a stainless machine screw or an aluminum rivet?
__________________
1st rule of yachting: When a collision is unavoidable, aim for something cheap.
"whatever spare parts you bring, you'll never need"--goboatingnow
"Id rather drown than have computers take over my life."--d design
Terra Nova is offline   Reply With Quote
Old 04-02-2016, 23:50   #19
Registered User
 
four winds's Avatar

Join Date: Oct 2010
Location: Wandering the US Gulf Coast
Boat: 78 Pearson323 Four Winds
Posts: 2,138
Re: Best way to fasten something to a Sailboat Mast

Quote:
Originally Posted by Terra Nova View Post
What do think would shear quicker, a stainless machine screw or an aluminum rivet?
Depends on how long it takes crevice corrosion and dissimilar metals to weaken the bolt.
__________________
Life begins at the waters edge.
four winds is online now   Reply With Quote
Old 05-02-2016, 00:22   #20
Registered User
 
leftbrainstuff's Avatar

Join Date: May 2011
Location: San Francisco and Australia
Boat: Liberty 458
Posts: 1,978
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
Monel rivets. You also need to isolate using tefgel or mylar.

Always use coarse threads on non ferrous material. You need a minimum of one diameter thread depth. Anyrhing less use rivets.

Sent from my SM-N900T using Cruisers Sailing Forum mobile app
__________________
leftbrainstuff is offline   Reply With Quote
Old 05-02-2016, 00:42   #21
Senior Cruiser
 
delmarrey's Avatar

Cruisers Forum Supporter

Join Date: Mar 2003
Location: Now in Blaine, WA
Boat: Modified Choate 40
Posts: 10,702
Images: 122
Re: Best way to fasten something to a Sailboat Mast

Quote:
Originally Posted by four winds View Post
Depends on how long it takes crevice corrosion and dissimilar metals to weaken the bolt.
Agreed! I've seen masts with rivets and screws both, pulled out.
What's really bad is when a rivet is pulled out and leaves an ******* and cracks. At least if a screw pulls out it can be replaced with a rivet.

Being a Machinest for 45 years I've learned there are options. Screws, usually being SS, I recommend using if you know you're going to be removing on occasion, and that you use a sealer (Tef-Gel). Fine thread or course, it doesn't matter. The fine thread one can just get tighter but will also strip out easier when tightening.

But for any fitting that is going to have a lot of vibration like an eyelet or track I'd recommend rivets. They will not work loose with stress, if installed properly. The nice thing about rivets is that they crimp themselves to the mating metals much like a wire crimp but with more tightness then a screw.

So, it really comes down to the application. As well, be sure to use the Tef-gel behind SS fittings.

What would be ideal would be self-clinching nuts but getting them inside the mast is a big ordeal.
__________________
Faithful are the Wounds of a Friend, but the Kisses of the Enemy are Deceitful! ........
A nation of sheep breeds a government of wolves!

Unprepared boaters, end up as floatsum!.......
delmarrey is offline   Reply With Quote
Old 05-02-2016, 02:06   #22
Zai
Registered User

Join Date: Mar 2011
Location: Athens
Boat: 2011 Bavaria 36 Cruiser
Posts: 144
Re: Best way to fasten something to a Sailboat Mast

I've used these rivet nuts with good results in aluminum.

__________________
Zai is offline   Reply With Quote
Old 05-02-2016, 08:31   #23
Registered User

Join Date: Dec 2014
Location: Australia
Boat: Pearson 365
Posts: 312
Re: Best way to fasten something to a Sailboat Mast

Quote:
Originally Posted by Terra Nova View Post
What do think would shear quicker, a stainless machine screw or an aluminum rivet?
Obviously the aluminium rivet. Less obviously it goes to the number of fasteners you use.

What do think would shear quicker, a stainless machine screw or 20 aluminium rivets?
__________________
'give what you get, then get gone'
ZULU40 is online now   Reply With Quote
Old 05-02-2016, 08:47   #24
Registered User

Join Date: Apr 2011
Location: Florida
Boat: Nonsuch U30
Posts: 78
Re: Best way to fasten something to a Sailboat Mast

I have a Nonsuch 30 with a free-standing mast. You do not drill into a Nonsuch mast. The preferred method is to use stainless steel bands with rubber or plastic under the band. This is the strongest way to attach to any mast.
__________________
Sdwcheney is offline   Reply With Quote
Old 05-02-2016, 09:23   #25
Registered User
 
Terra Nova's Avatar

Join Date: Apr 2007
Location: Marina del Rey, California
Boat: Freya 39 cutter- Terra Nova
Posts: 3,645
Re: Best way to fasten something to a Sailboat Mast

I once had to haul someone up the mast on a Tayana 55, using the main halyard winch. On the way down he used the winch as a final step before then stepping onto the deck. Once his weight came off the halyard, and onto the winch, the winch fell on the deck. Corroded pop rivets had barely held the winch base bracket to the mast.
__________________
1st rule of yachting: When a collision is unavoidable, aim for something cheap.
"whatever spare parts you bring, you'll never need"--goboatingnow
"Id rather drown than have computers take over my life."--d design
Terra Nova is offline   Reply With Quote
Old 05-02-2016, 09:31   #26
Registered User

Join Date: Feb 2014
Location: Deltaville, VA
Boat: Moody M46 46
Posts: 263
Re: Best way to fasten something to a Sailboat Mast

A lot of somewhat conflicting advice here. I did see the first posting which advocated in priority some things with rivets first. But then came conflicting opinions, but the trend seems to be monel rivets or big aluminum, heavy duty rivets with some sort of sealer against galvanic corrosion.

The fellow with the Nonsuch has an interesting idea, but I'm looking to install an eye for a whisker pole and the location will be above the gooseneck. A steel band would wreak havoc with in-mast furling--or hanks for that matter.

But all good stuff. Thanks all.
__________________
Moody46CC is offline   Reply With Quote
Old 05-02-2016, 11:24   #27
Registered User

Join Date: Feb 2016
Location: Lansdale, PA
Boat: Chrysler 22
Posts: 5
Re: Best way to fasten something to a Sailboat Mast

Hi, new member here. I just wanted to add that threads are evaluated for strength in the shear capability at the bottom of the loaded portion of the thread, either inside or outside thread. That said, the engagement surface area of the other threaded component's threads determines this shear surface. Explained: if a thread is engaged to the bottom of its root, then the shear surface is the width of the root of the thread (or the distance from one revolution root to the next root, which would equal the pitch of the thread). For example, 1/4-20 threads have a pitch of 20 threads per inch, so the shear surface width would be 1/20" or .050", and the shear area is .050" x the number of threads engaged x pi x diameter of the hole or bolt at the root of the thread. And to find shear strength, the shear area is then multiplied by 1/2 the tensile strength of the base material.
But, threads are never fully engaged with each other. Therefore, the looser the fit, the less thread engagement surface, the smaller the thread base in width, the smaller the shear area, and the weaker the threaded connection. You have to measure each part to determine thread engagement. Make sense? You can extract fine and coarse thread maximum shear areas from the Machinery's Handbook, and it may be on line somewhere.
I really wanted to point out that there is another way of attaching stuff to your mast. I don't know, but I'm guessing that the mast material is not really strong for threading since it needs to be soft so it is easy to extrude into a mast. A great alternative attachment method is the threaded rivet nuts sold by, for example, McMaster-Carr. Aluminum rivet nuts size 1/4-20 for 1/8" thickness are shown here: McMaster-Carr . You need the correct drill bit and a rivet set tool to install, but the threads are probably much stronger and hardened, and would require anti-corrosives anyway, inside and out. There are no SS rivet nuts listed, but they may be available somewhere else. Have a look. CW
__________________
chasmains is offline   Reply With Quote
Old 05-02-2016, 12:47   #28
Senior Cruiser
 
Rockyscience's Avatar

Cruisers Forum Supporter

Join Date: Jul 2015
Location: IN./TX.
Boat: Custom Roberts 65' Ketch (Sold it)
Posts: 73
Re: Best way to fasten something to a Sailboat Mast

Hi All, I have been using one of these for years to pop threads into thin metals.
It works great and the blind nuts can be aluminum, just put any size you wish in like a rivet.
Attached Thumbnails
Click image for larger version

Name:	nutter.jpg
Views:	112
Size:	30.3 KB
ID:	118387  
__________________
Rockyscience is offline   Reply With Quote
Old 05-02-2016, 12:57   #29
Registered User

Join Date: Dec 2015
Location: Panama City, FL
Boat: 1974 Pearson 39 Yawl
Posts: 29
Re: Best way to fasten something to a Sailboat Mast

When I stumbled onto this forum, I was thrilled with the amount of knowledge shared and the lack of opinions stated as facts argued ad nausea. I do have to pipe up on this particular thread however. I would first agree with all preferring the rivet solution vs. threads of any sort. I do, however, have to point out the error in the fine/course thread argument going on. Assuming sufficient length of engagement, proper tap drill size, lubrication on taps, etc. etc., the fine thread is stronger than the course thread for the following reasons:
1) In tension (pulling against the threads) the stress area of the fine thread is larger, and in shear (pulling the fastened object along the adjacent surface) the minor diameter is also larger.
2) Fine threads have less tendency to loosen since the side of the thread incline is smaller and hence so is the off torque.
Other advantages include finer adjustment when needed (irrelevant in this ap), more easily tapped in hard materials and thin walls, and lesser torque required for equivalent bolt preloads.
On the other hand:
1) Fine threads are more susceptible to galling
2) Generally require longer thread engagements
3) Are more susceptible to damage and fouling
4) Metric versions are generally more difficult to obtain.
On the neg
__________________
Capt_Flrp is offline   Reply With Quote
Old 05-02-2016, 13:27   #30
Senior Cruiser

Cruisers Forum Supporter

Join Date: Dec 2010
Location: Cruising Indian Ocean / Red Sea - home is Zimbabwe
Boat: V45
Posts: 1,282
Re: Best way to fasten something to a Sailboat Mast

When I attached mast steps Spar Craft advised me to use Monel rivets. I didnt even realise there were high strength rivets available, so thanks. That also means ordering some now!!


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
__________________

__________________
Bulawayo is offline   Reply With Quote
Reply

Tags
mast, sail, sailboat

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Best way to safely climb my mast cburger Deck hardware: Rigging, Sails & Hoisting 35 07-01-2015 09:41
Best way to re-attach cam cleat to mast? OldFrog75 Deck hardware: Rigging, Sails & Hoisting 15 04-08-2013 21:49
Something to Play with for Beach Potlucks that Leaves Something Good Behind knothead General Sailing Forum 1 04-05-2010 14:06
Best Way to Clean an Old Mast? Azura Solana Construction, Maintenance & Refit 2 13-08-2009 08:46



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 20:22.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.