[Public-List] Design of derrick to raise Alberg 30 mast

[Don Campbell]

Michael;
    The cheapest (and safest) way may be to join a club that has a jib 
crane that is either a nominal cost or free to members. That was so for 
my case with the closest YC and  annual dues of $160 a year, $5.75 per 
use of the crane,  and then reciprocals thrown in for good measure.
    Prior to that, I was dismayed at the cost I was charged and so 
purchased the components of a similar A frame to the Chesapeake system. 
(1 1/2"  Aluminum or steel scaffolding, 2 joins, one swivel and a piece 
of 3/8 cable with connector clamps to hold the lifting blocks, block 
system from vang and 160 feet of 7/16" braid dedicated solely for mast 
lifting and stored at home in a place not subject to dust,  light or 
humidity). However,  I think they have two 12 foot long sections in 
their system for the legs and I have one 12 and one 14 foot section per 
side which raises the block a bit higher than the spreaders and is easy 
to work with. There are safety issues with this system this long in the 
leg,  from the initial raising past the first 20 degrees to the 
stability of the legs once up and lifting. To get around this I made two 
wooden brackets for the feet that bolt to the chainplates. I also made a 
horse to hold the A frame at the aft end of the cockpit because the 
leverage of the 26 foot frame is not in your favour. At this stage you 
want the mast on the centerline of the boat, top of the mast forward, 
track on top steaming light to the deck. Then I put the boat in a dock 
that was a 3 sided slip so that I could take dock lines and tether the 
legs at the join of the two pieces  both fore and aft to the wharves on 
both sides,  taking away any forward and aft play in the legs and some 
of the inward strain once they start to bear the weight of the mast. 
This is crucial in the procedure because if the legs get out of column, 
they will possibly let the frame and mast down at any stage of the 
raising or lowering, timing unknown! If they hold and are out of column, 
it is quite scary and unsafe for all concerned. I think the mast with 2 
winches and standing rigging is about 200 pounds.
    I also built a mast carrier to move the mast on the ground from the 
boat in the lifting dock to my trailer. It is about 6 feet long and 26" 
inches wide with just 2 wheels with air inflated tires - 8.5 x 4,  I 
think they are from TSC and put a pair of boards on one end so that the 
mast cannot lie flat on the rack but must lie with the track either up 
or down. If the spreaders are about the center of the carrier, it is 
balanced. The materials used to build the cart were all white oak 
because that was the strongest wood I had in the shed and all pieces are 
bolted with 1/4" carriage bolts of appropriate length.
    A very simple design with 2 x 3 corners about 30" long (and the top 
corners are higher than the top 1 x3 sides, bottom flush with bottom 
sides), and 1 x 3 top and bottom for the circumference with one 1 x 3 
cross brace per side and end. There is a piece of 1 x 10 on the bottom 
across the width to hold the wheels, neither of which swivel. The 
carrier could be longer than 6 feet if you wish but that was the length 
of what I had and it works fine for one person to manage but is perhaps 
slightly tippy if the ground is uneven. Two people are good for 
stability there or make it slightly wider.
    WRT  raising the mast , I have never done this alone, for 2 
reasons,  both safety conscious: the first is that one pair of eyes is 
not enough to see pitfalls and the second is that one body, if injured, 
cannot go for help. That said, the second person does not have to do 
much in the process.
    My wife and I have put the mast up with the A frame system in 6 
hours with just the 2 of us. Basically only one of us knew the system 
and so the second person does mostly watch. It took about 2 hours to 
assemble the A frame pieces, lay things out and fasten the foot blocks 
to the chainplates, make sure the stays for the A frame were correctly 
led for the spreaders, attach a 4:1 block and tackle system without that 
system being fouled, raise the A frame, secure the stays, affix the dock 
lines at the 14' height and to the wharf and thoroughly check each 
position to see that there had been no weakness in the lifting system. ( 
3 checks at each place). Some time in that 2 hours was taken to make 
sure the mast was dressed, halyards in place, spin blocks and lines were 
in place, spreaders in place, things so far  not fouled, lifting choker 
in place with a retrieval line in that system, and that all standing 
rigging was aligned and not fouled. (Check 3 times again). Lunch then 
took 45 minutes. Lifting then began with a winch and took about 25 - 30 
minutes with no hurry, to make sure the legs stayed in column and the 
mast was safe at every level and that the spreaders stayed on the 
correct side of the frame at all times (difficult to do with the slight 
angle on the A frame and the ever shrinking distance between the legs as 
the spreaders go up with the C of G moving forward of the lifting 
point!). This meant that the centre of gravity of the mast had to be 
directly below the lifting block for the whole lift, so some adjustment 
of the base of the mast all the way through the lift was necessary. Then 
the mast was lowered onto the deck fitting. It took one person about 30 
minutes to make sure the 4 uppers were affixed to chainplates or the 
head. Rocking the boat is not an option here since the legs are secured 
to the wharf on both sides, so slow movements and careful work is 
required. Then the lowers were attached and it took about an hour and a 
half to attach these, measure and tighten the rig and another 15 -20 
minutes to lift the A frame and lower it, stow it and clean up. I know 6 
hours sounds a lot but that is what it takes if you are with only 2 
people, including lunch,  and complete the rigging in a safe manner so 
that everyone walks away in one piece. Lowering is much easier I think, 
although keeping the legs in column is equally important. The difficult 
chore with restricted labour is to get  the mast into position in the 
first place. It can be done if the strong person only lifts only the top 
end of the mast from the cart and the second person slides the cart to 
the top end as the mast base rests on a plank across the push pit and 
has been secured there so it will not slide into the dock. The mast is 
then lifted onto the boat and laid in the centre of the boat before the 
A frame assembly is even contemplated.
    Lifting the A frame down is easy with a loop in the main halyard or 
using the choker retrieved from the mast lift on the main halyard. The 
only care needed is to be sure that the lower part of each leg is secure 
in its coupler so that they don't let go and come crashing down on the 
deck as a vertical projectile with only the end surface area hitting and 
piercing the deck.
    To lower the mast,the biggest trick is to get the A frame stay over 
the spreader. Lowering the A frame is then the last big chore and there 
is a point at about 40 degrees where the leverage is well against you, 
so extra help is a benefit to either catch a leg or keep the base of the 
legs down.
    As for figuring a better way, this is the method of the British and 
American  navies when it came to raising wooden masts. Somehow I have a 
feeling they had all the time in the world to think this one through and 
if it worked for them with big wooden sticks, then it will work for you, 
manpower differences considered.
     Jib cranes are much safer, provided the cable is good, if manpower 
is limited. It really still takes two people with a jib crane too, to 
both lift and control the mast base since these are usually manual 
winches on these cranes and the winch is ashore while the mast is over 
the hull.
    There, my winter thinking is done and your winter project has just 
begun! Whatever you do be safe. This is not a job to do on windy days or 
on floating pontoon wharves I would say. If anything gives on this 
project, chances are good that a person will be injured and for sure 
there will be damage to the boat and or mast. In that case $150 a time 
is sure not expensive.
Don
#528

Michael Connolly wrote:
> Hello all,
>    
>   I am thinking about how I can beat the high cost of mast removal and re-stepping at haul out and splash times.  $150.00 each way over twenty years is 6K.  I am in the process of designing a cart to move the mast around easily on shore and down or to the dock. I would like to design something that one person can set up and operate.
>    
>   I know that Mike Lehman stores the derrick owned by the CBAA.  I understand that it is mfg of steel and is quite heavy and a bit unwieldy to set up. This might be a logical spring board to begin the new design process.  What works well and not so well about the current rig?
>    
>   Any one know the average mast weight with a head sail furler system?.............350 pounds?
>    
>   Collectively the Alberg 30 owners have more than enough brain power to come up with a light weight design for a derrick.  Then George can post on the website and we can all benefit.
>    
>   I could design a hinged mast Tabernacle and use a gin pole, but I still need to get the mast in position by myself. So if I need a derrick (or some such device) to position the mast from the dock or next to the boat to the deck, why not design said derrick to raise the mast as well?  Besides I am not sold on the hinged Tabernacle idea for this large a mast.
>    
>   OK, time to hear from all you Engineer types out there.  Seems like a good winter project to get this thing designed. Thanks in advance for your input.
>    
>   Michael Connolly
>   #133 Lorrie Rose
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