Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 17-11-2010, 23:04   #1
Marine Service Provider
 
Ben M-P's Avatar

Join Date: Oct 2010
Location: Southern California
Boat: Fareast, Mariner 40'
Posts: 177
Converting Keel-Stepped to Deck-Stepped Mast

Anyone heard of it being done?
How difficult would it be?
I'm asking mostly out of curiosity.
__________________

__________________
Godspeed, as you travel the wave-road.
http://goingafloat.blogspot.com/
Ben M-P is offline   Reply With Quote
Old 17-11-2010, 23:59   #2
Registered User
 
ozskipper's Avatar

Join Date: Aug 2010
Location: NSW Australia
Boat: Traditional 30
Posts: 1,981
Cant be too hard. Cut the mast at deck height. Seal the deck and add a mast step. Insert a compression post. Re do electric cables through the deck and thats about it. Sounds like a five minute job lol. Ok it isnt. But it certainly isnt a hard one

Cheers
Oz
__________________

__________________
ozskipper is offline   Reply With Quote
Old 18-11-2010, 00:21   #3
Senior Cruiser
 
Minggat's Avatar

Cruisers Forum Supporter

Join Date: Apr 2008
Location: Hawaii, South Pacific bound
Boat: Islander 36
Posts: 1,221
Quote:
Originally Posted by ozskipper View Post

....... Cut the mast at deck height. ..... Insert a compression post.....
Use the section of the mast that you just cut for the compression post..?
__________________
Minggat
Minggat is offline   Reply With Quote
Old 18-11-2010, 10:17   #4
cruiser

Join Date: Nov 2008
Posts: 506
No, No, No!
A deck stepped mast requires a stronger section than a kel stepped mast. Anyone who has ever desifgned boats knows that. Unless maybe your keel stppped section is oversized ansd that is posible. But there is some engineering involved in making this change.
__________________
bob perry is offline   Reply With Quote
Old 18-11-2010, 12:31   #5
Senior Cruiser
 
Jim Cate's Avatar

Cruisers Forum Supporter

Join Date: May 2008
Location: cruising SW Pacific
Boat: Jon Sayer 1-off 46 ft fract rig sloop strip plank in W Red Cedar
Posts: 11,455
So, yes, I too think it could be done given enough money and talent, but why in the world would anyone even consider such a move. Madness...

Jim
__________________
Jim and Ann s/v Insatiable II , lying Port Cygnet, Tasmania once again
Jim Cate is offline   Reply With Quote
Old 18-11-2010, 16:04   #6
Registered User
 
ozskipper's Avatar

Join Date: Aug 2010
Location: NSW Australia
Boat: Traditional 30
Posts: 1,981
Quote:
Originally Posted by bob perry View Post
No, No, No!
A deck stepped mast requires a stronger section than a kel stepped mast. Anyone who has ever desifgned boats knows that. Unless maybe your keel stppped section is oversized ansd that is posible. But there is some engineering involved in making this change.
Bob, please bare with me here.. If I get a piece of 1in diam pipe and try to bend it with my hands 2 inches apart its much harder than if I try to bend it at 2ft apart. Leverage.

Why wouldnt a shorter mast be stronger than a longer mast? Assuming the compression post was taking the loads the previous section used to take I am confused how shorter is weaker.

Cheers
Oz
__________________
ozskipper is offline   Reply With Quote
Old 18-11-2010, 20:12   #7
Registered User
 
Unicorn Dreams's Avatar

Join Date: Aug 2007
Location: Clear Lake Marine Services - Seabrook, Texas
Boat: Gulfstar, Mark II Ketch, 43'
Posts: 2,359
Just like Bob said.
A keel stepped mast is made out of thinner walled material as it h support part way up..
My ketch has both a deck and keel stepped mast. The main has a thinner wall thickness than the mizzen which is deck stepped.
Main mast is 63' from keel to mast head.
Mizzen is 35' from deck to mast head..
I believe I would listen to Bob Perry as this is his line of work and has designed many a beautiful yacht....
__________________
Formerly Santana
The winds blow true,The skies stay blue,
Everyday is a good day for SAILING!!!!
Unicorn Dreams is offline   Reply With Quote
Old 19-11-2010, 07:50   #8
cruiser

Join Date: Nov 2008
Posts: 506
Oz:
Your analogy is incorrect.
If you hold the mast at the keel step and then at the partners you effectively stiffen the lower part of the section. This is called "one fixed end and one pin end". If you just have the mast sitting on the top of the deck or coachroof you have "two pin ends" an you need higher moments of intertia to achieve the same stiffness.

Find a copy of Skene's Elements of Yacht Design. It's all in there.
__________________
bob perry is offline   Reply With Quote
Old 19-11-2010, 07:57   #9
Registered User

Join Date: Jul 2009
Boat: Nassau 42 SV Ceol Mor
Posts: 789
This isn't meant to sound rude but I am afraid it might come across as such. Here goes anyway- why? Why would you want to convert your mast at all? If you want a deck stepped mast, buy a boat with that feature. If you prefer keel stepped, then go with that from the beginning.

I just remember looking at so many boats prior to purchase that had owner modifications that really left me scratching my head. If you are buying a boat, I would hope you've done some research into the design and designer. If you like a boat enough to buy it, you should trust that the designer used his/her best judgement as to the best type of structure for that particular design. If you don't trust the designers judgement, buy a different boat!
__________________

__________________
S/V Ceol Mor
42 Nassau Undergoing refit in Kemah, Tx
Our little blog has moved: www.theceolmors.blogspot.com
Mimsy 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
Keel-Stepped vs Deck-Stepped . . . jdeatsch Deck hardware: Rigging, Sails & Hoisting 54 19-11-2010 17:20
Aluminum Keel-Stepped Mast to Iron Keel - Grounded ? endoftheroad Construction, Maintenance & Refit 11 30-09-2010 15:47
Deck-Stepped Mast sandycohen Deck hardware: Rigging, Sails & Hoisting 14 24-12-2009 18:13
Water in a deck stepped Mast... drh1965 Construction, Maintenance & Refit 15 14-09-2007 22:05
What is the Advantage of a Keel Stepped Mast? 44'cruisingcat Monohull Sailboats 44 01-12-2006 19:18



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 07:15.


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.