Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 26-08-2008, 14:09   #1
Registered User

Join Date: Mar 2008
Location: The Sea
Boat: Coronado 30 - Lady Eliza
Posts: 241
Images: 11
Mast thickness

I want to know the thickness of the mast material so I can get the right size rivets for the steps. Will measuring the wall inside where a halyard comes out give me the right number or does the thickness vary along the mast?

Thanks,
J
__________________

__________________
"It is never too late to be who you might have been." -George Eliot
Jack Long is offline   Reply With Quote
Old 26-08-2008, 17:10   #2
Senior Cruiser
 
Cheechako's Avatar

Cruisers Forum Supporter

Join Date: Aug 2006
Location: Skagit City, WA
Posts: 19,369
the thickness may vary going around the mast. I have seen some extrusions like that. Most masts are extruded so they are similar thickness in the longitudinal direction. generally, they should be pretty close all around except near "tracks" etc
__________________

__________________
Cheechako is offline   Reply With Quote
Old 26-08-2008, 17:30   #3
Registered User
 
Squeaks's Avatar

Join Date: May 2007
Location: Oxnard / Alameda, CA
Boat: Golden Gate 30, Westerly 23
Posts: 169
Images: 3
Jack:
Others will hopefully back me up but drilling and tapping with SST (stainless steel) machine screws would be much stronger. But SST rivets, not alluminum, at a minimum.
__________________
We can't change the wind - but we can adjust our sails.
Squeaks is offline   Reply With Quote
Old 26-08-2008, 20:00   #4
Registered User

Join Date: Mar 2008
Location: The Sea
Boat: Coronado 30 - Lady Eliza
Posts: 241
Images: 11
Planning on SST rivets. 6 per step.

My instinct was to go with screws but I was really leery about trying to tap 70ish holes. Then I noticed most of the boats around mine were riveted and I rejoiced.
__________________
"It is never too late to be who you might have been." -George Eliot
Jack Long is offline   Reply With Quote
Old 26-08-2008, 21:51   #5
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
[COLOR="Red"]NOT![/COLOR]

Quote:
Originally Posted by Squeaks View Post
Jack:
Others will hopefully back me up but drilling and tapping with SST (stainless steel) machine screws would be much stronger. But SST rivets, not alluminum, at a minimum.
Most masts the wall thickness is less then 1/8" thick unless you get into the very large yachts. If one were to drill and tap for a #10-32 screw there would only be 4 threads in a 1/8" thickness and even less in smaller masts.

It's a general rule to have at least a depth of thread 1-1/2 times the diameter of the screw/bolt for true holding power, even more so in aluminum.

Rivets are stronger in this case only because they would never pull out without distorting the metal into and external *******. Where as the threads would strip out just by over tightening.

Although I did drill and tap my mast for some cheek blocks for the lazy jacks which have a side-ways pull, but everything else like the gooseneck, steps, pole track, boom-vang, spreaders and thru blocks are all riveted. I still may end up pulling the screws and installing rivets if they show signs of coming loose.

The other thing about screws is they leave a shape protrusion sticking out the inside of the mast for lines to snag on. A selection of short screws was important in my case. Whereas, rivets leave a rounded knob on the inside.



http://www.answers.com/topic/rivet
__________________
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 26-08-2008, 23:51   #6
Senior Cruiser
 
Alan Wheeler's Avatar

Cruisers Forum Supporter

Join Date: Dec 2003
Location: Marlborough Sounds. New Zealand
Boat: Hartley Tahitian 45ft. Leisure Lady
Posts: 8,038
Images: 102
If you can find, use Monel rivits. These will not cause the corrosion issues SST will. If you do use SST, then coat in lanacote before placing them in the hole. If the step is SST as well, then you need to use a urathane adhesive sealant like 3M5200 or Sikaflex or any similar, as a bedding compound. A small amount will squeez out. Just wipe clean with some turps on a rag.
If you did go for a thread, you always want to use a corse thread like UNC etc. on any threads under 8mm(5/16). From 8mm up you can use the finer metric threads. Coat threads in lanacote. For speeding up tapping the thread, you can use a battery drill on a slow speed and a good starting tapping. Just spin the tap all the way through. It's quick and works well.
Be very cautious of using Aluminium rivets. They are soft and can shear without you ever knowing they have. Monel is strong and corrosion resistant.
Most mast sections are similar in thickness all the way around. But watch for twin section extrusions. These will have a seam down the sides and the mast is twice the thickness along that seem. A rivet slightly longer than needed will still take up.
__________________
Wheels

For God so loved the world..........He didn't send a committee.
Alan Wheeler is offline   Reply With Quote
Old 27-08-2008, 09:20   #7
Senior Cruiser
 
Cheechako's Avatar

Cruisers Forum Supporter

Join Date: Aug 2006
Location: Skagit City, WA
Posts: 19,369
+1 on Lanocote at any SS alum interface. I used a jar of anhydrous lanolin for year for everything from the threads on anchor clevis' to screws in the mast, to tapered seacock lubricant and even on my turnbuckles etc. It's the only thing that will keep those ss screws from becoming a permanent part of the mast! I believe Lanocote is mostly just Anhydrous lanolin.
__________________
Cheechako is offline   Reply With Quote
Old 27-08-2008, 09:46   #8
Registered User

Join Date: Aug 2006
Location: Leucadia, California
Boat: Stevens 47 Komaru
Posts: 428
The thickness depends on your ali section. I have attached pics of my old and new mast section. The new section is much thicker at the side walls due to how it is constructed. If you mast is oval chances are that the thickness is consistent. I would try to talk you out of mast steps, they are such a pain and a place for your lines to get hung up on. In my opinion they also ruin the lines of the boat.

Jack
Attached Thumbnails
Click image for larger version

Name:	DSC03614.jpg
Views:	146
Size:	502.4 KB
ID:	4850   Click image for larger version

Name:	DSC03615.jpg
Views:	192
Size:	369.5 KB
ID:	4851  

__________________
Stevens 47 is offline   Reply With Quote
Old 27-08-2008, 10:00   #9
Moderator Emeritus
 
David M's Avatar

Cruisers Forum Supporter

Join Date: Sep 2007
Location: San Francisco Bay
Boat: research vessel
Posts: 10,152
If I could add a little, boatyards are going with Tefgel in place of lanolin as a way of stopping electrolysis caused by dissimilar metals. I have used both, I agree that the Tefgel is the better stuff.
__________________
David

Life begins where land ends.
David M is offline   Reply With Quote
Old 27-08-2008, 10:14   #10
Eternal Member
 
imagine2frolic's Avatar

Join Date: Feb 2008
Location: Las Brisas Panama AGAIN!
Boat: Simpson, Catamaran, 46ft. IMAGINE
Posts: 4,508
Images: 123
At the base of the mast should be a whole for the wiring to exit
__________________
imagine2frolic is offline   Reply With Quote
Old 27-08-2008, 13:57   #11
Registered User

Join Date: Mar 2008
Location: The Sea
Boat: Coronado 30 - Lady Eliza
Posts: 241
Images: 11
I don't think the steps ruin the lines. Certainly not any more than solar panels, wind gens, dinghies, and/or male crew.

I will be solo most of my time after the Ha-Ha and that makes the steps pretty compelling. There are other ways to get up by yourself but nothing that isn't a big hassle. In another post somebody made the point that with the steps he is very diligent with various maintenance, repairs, spot checks, etc...
__________________

__________________
"It is never too late to be who you might have been." -George Eliot
Jack Long is offline   Reply With Quote
Reply

Tags
mast

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
going up the mast shellback Deck hardware: Rigging, Sails & Hoisting 14 10-09-2008 17:49
Retrofitting a wood mast vs current metal mast grefark Deck hardware: Rigging, Sails & Hoisting 7 07-09-2008 22:44
Need a mast vicman Classifieds Archive 8 26-05-2008 14:34
My mast sailboat man Classifieds Archive 1 15-05-2008 14:31
Mast ksmith Construction, Maintenance & Refit 5 17-08-2007 23:05



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 11:16.


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.