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22-11-2010, 02:17
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#1
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Registered User
Join Date: Oct 2010
Location: canberra australia
Boat: forna 37 van de stadt still building name maybe kokomajo
Posts: 19
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Mast Step
HI,
I am going to mount my mast step on my cabin top and wondering how many bolts, what pattern and size of bolts? The mast is 200mm wide and will be mounted on a 37ft yacht. Worried about movement over time, thinking about 2 12mm bolts in line. Any ideas would be great.
Thanks Mark
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22-11-2010, 02:20
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#2
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Registered User
Join Date: Dec 2008
Location: St. Georges, Bda
Boat: Rhodes Reliant 41ft
Posts: 4,131
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Quote:
Originally Posted by markkoby
HI,
I am going to mount my mast step on my cabin top and wondering how many bolts, what pattern and size of bolts? The mast is 200mm wide and will be mounted on a 37ft yacht. Worried about movement over time, thinking about 2 12mm bolts in line. Any ideas would be great.
Thanks Mark |
What boat, what mast, what support structure below deck, what does designer spec.
__________________
so many projects--so little time !! 
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22-11-2010, 02:27
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#3
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Registered User
Join Date: Oct 2010
Location: canberra australia
Boat: forna 37 van de stadt still building name maybe kokomajo
Posts: 19
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It is a 37 ft Van de stadt, the plans dont show and it has a aluminium post in the cabin. The mast is 15 metres tall. The plans only show how to build the cabin top and what needs to be under the mast step. I spoke to mast builder and they say 2 or 3 bolts but not convincing. If I just put two bolts it may move over time and just wondering what others have done.
Thanks
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22-11-2010, 02:48
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#4
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Senior Cruiser
Join Date: Oct 2007
Location: 29° 49.16’ N 82° 25.82’ W
Boat: Pearson 422
Posts: 16,306
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The load on the mast will be mostly compression, very little sheer. On the last boat I had with a deck stepped mast (32' with 42' mast) the step had 4 bolts through the deck into a backing plate in the cabin top.
__________________
The water is always bluer on the other side of the ocean.
Sometimes it's necessary to state the obvious for the benefit of the oblivious.
Rust is the poor man's Loctite.
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22-11-2010, 04:11
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#5
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Registered User
Join Date: May 2008
Location: We're technically refugees from our home in Yemen now living in Lebenon
Boat: 1978 CT48
Posts: 5,964
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That sounds like a big mast section (200mm) for that size boat.
Got any pictures of the step?
Seems like you would have 4 bolts in any case.
Does the compression post have a plate on top that can act as a backing plate?
I'm not real familiar with deck stepped masts.
__________________
James
S/V Arctic Lady
I love my boat, I can't afford not to!
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22-11-2010, 05:06
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#6
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Registered User
Join Date: Nov 2005
Location: Ohio
Posts: 2,933
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Just make sure the material you use between the mast butt and the compression post can't compress.
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22-11-2010, 05:10
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#7
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Registered User
Join Date: May 2008
Location: We're technically refugees from our home in Yemen now living in Lebenon
Boat: 1978 CT48
Posts: 5,964
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Quote:
Originally Posted by Joli
Just make sure the material you use between the mast butt and the compression post can't compress.
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Absolutely 
__________________
James
S/V Arctic Lady
I love my boat, I can't afford not to!
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22-11-2010, 06:33
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#8
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Senior Cruiser
Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 49,339
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Most of the commercial pre-drilled mast steps I’ve seen, have 4 bolt holes.
➥ http://www.charleston-spar.com/us/te...steps_perf.pdf
Rig-Rite, Inc. Should be able to offer expert advice.
Phone: (001) 401-739-1140
Fax: (001) 401-739-1149
Web ➥ Rig-Rite Inc. - Masts, Booms, Spars, Rigging, and Hardware for Sailboats.
And ➥ Mast Steps
__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"
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22-11-2010, 07:44
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#9
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Registered User
Join Date: Dec 2008
Location: ontario canada
Boat: grampian 26
Posts: 1,743
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What Gord says, four bolts. Don't cheap out and err on the side of caution.
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22-11-2010, 11:34
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#10
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Registered User
Join Date: Aug 2008
Posts: 39
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When I had my deck stepped mast (35ft) I had a stainless steel step fabricated as a plate with four bolt holes and a circular "hoop" to take the mast section welded on, this was through bolted to the compression post. I had drain holes at the sides to keep the salt water out.
It worked well.
__________________
 Sailbadoften
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22-11-2010, 13:07
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#11
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Registered User
Join Date: Dec 2008
Location: ontario canada
Boat: grampian 26
Posts: 1,743
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mast step
Another question. Where is the best place to put the hole for the mast wiring?
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22-11-2010, 15:00
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#13
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Registered User
Join Date: Feb 2009
Location: A real life Zombie from FL
Boat: Gulfstar 53 - Osiris
Posts: 5,416
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Quote:
Originally Posted by perchance
Another question. Where is the best place to put the hole for the mast wiring? |
That depends upon how big a hole is needed. If it is small then anywhere several inches above the mast step so that the wires do not sit in trapped water inside the mast tube. If the hole is larger then in the side - assuming an oval mast shape - so that the hole is a small fraction of the side area. It is also a good idea to be sure to offset a series of holes so that they are not in a straight line - i.e., stagger them forward and aft, up and down so that they cannot form a "perforation" line around the mast.
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24-11-2010, 01:47
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#14
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Registered User
Join Date: Oct 2010
Location: canberra australia
Boat: forna 37 van de stadt still building name maybe kokomajo
Posts: 19
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 Thanks for all the replys
Regards Mark
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