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Conference unifix::sailing

Title:SAILING
Notice:Please read Note 2.* before participating in this conference
Moderator:UNIFIX::BERENS
Created:Wed Jul 01 1992
Last Modified:Mon Jun 02 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:2299
Total number of notes:20724

421.0. "* Winter Spar Size *" by PENNSY::GREEN () Tue Oct 14 1986 14:27

    			* WINTER SPAR *
    
    I am pulling my mooring bouy next week and would value some quick
    advise on sizing a winter spar.  I intend to use a 4x4 with an
    eyebolt to shackle onto the chain.
    
    There will be 50# of 1/2" inch chain that the spar will have to
    support.  What length shuld the spar be in order to support the
    chain??
    
    thanks......
    
    Ron
T.RTitleUserPersonal
Name		DateLines
421.1GRAMPS::WCLARKWalt ClarkTue Oct 14 1986 17:407
    I dont have a mooring, but I know what RI state moorings do over
    the winter.   They attach enough nylon line to a painted 2-3'
    piece of 4x4 to hook to the chain and allow it to rest on the bottom.
    That way they dont have to support the chains weight at all.
    
    Walt
421.2how long?PULSAR::BERENSAlan BerensWed Oct 15 1986 00:0423
The density of seawater is 64 lbs per cubic foot and density of 
Douglas fir is 33 lbs per cubic foot.

Therefore one cubic foot of Douglas fir has approximately 31 lbs of 
buoyancy. To support 50 lbs requires 50/31=1.61 cubic feet of Douglas 
fir. 

The actual dimensions of a nominal 4x4 are 3.5 inches x 3.5 inches, so a
mooring stake 19 feet long will just barely float when tethered to 50
lbs of chain (neglecting the buoyancy of the chain). 

I would suggest shackling a light chain (eg 3/16) between the mooring 
stake and the bottom. 3/16 chain weighs 0.4 lbs per foot, so you would 
need 15 feet of mooring stake per 100 feet of 3/16 chain. This assumes 
dry wood, so you ought to add a couple of feet and then add maybe 4' 
more so that the mooring stake is easily visible. Actually, you want 
more stake below the surface than above so that the stake floats more or 
less vertical. I would be reluctant to use nylon (re .1) for fear of
chafe wearing through it over the winter. Nylon is certainly easier and 
less bother, and if it is good enough for the government .....

Alan
421.3SWSNOD::RPGDOCDennis the MenaceWed Oct 15 1986 14:279
    
    RE: .1  "nylon"
    
    If this mooring were anywhere near a channel, wouldn't a nylon line
    be in danger from passing powerboats?
421.4GRAMPS::WCLARKWalt ClarkWed Oct 15 1986 16:5112
    RE: .3
    
    In what way ?
    
    
    Re: .2
    
    Yeah. Chafe could be a problem. Especially in an area where the
    bottom is rocky.
    
    Walt
421.5** Winter spar - chapter 1 conclusion **LEHIGH::GREENMon Oct 20 1986 10:4118
    And the results were.....
    
    I wound up at Marine Exchange in Danvers.  Kevin confirmed the idea
    that light chain would be a grand idea - lots of chafe through
    caused by ice.  He also had a great deal on chain!  
    
    With 25 feet of chain attached to an 8' length of 4x4 (painted with
    house paint, the mooring # and my last name carved in one end and
    a 3/4" hole drilled through in the other), this winter spar rises
    about 2 feet out of the water at high tide and looks quite sharp.
    
    My speculation is that a winter on the bottom will clean off a lot
    of this summer's accumulated mussels and weed.
    
    Thanks for the advise......
    
    Ron.