My DIY Gin Pole Attempt for CP23

[NateD]

After wresting my mast up twice with brute force (and the help of 1-2 other people) I decided I wanted to make a mast raising system that would allow me to do it single handed, or at least in a safer and less strenuous way. I liked brackish's system (http://cpyoa.geekworkshosting.com/forum/index.php?topic=2609.0) which he credits back to here (http://www.tropicalboating.com/sailing/mastraising.html).

Instead of using a bracket that sat in the mast step bracket, I wanted something that would ride on the bolt that goes through the mast and step bracket. I thought that having the mast and the gin pole both pivot on that bolt would balance any force created and take the strain instead of the relatively flimsy bracket absorbing the load. I have a small MIG welder and have experience welding steel, but not aluminum, and the pole would only be used a few times a year (and not carried onboard), so I decided to make mine out of mild steel. The pole itself didn't turn out very heavy, but the winch I used was heavy and doubled the weight of the whole thing.



The overall length is a little over 6 feet, so that it will fit lengthwise in the bed of the truck without turning it at an angle (important because I have the ladder, tools, and outboard back there when trailering). The forks at the bottom are 12" long, made of 1/4" x 1.75" mild steel flat stock. I don't remember the width measurement, but the two forks are just wide enough to fit around the outside of the mast step bracket. The rest of the pole is 1.5" 14 gauge square stock. There are two eye bolts at the top, one with a line that is tied to the bow cleat, and the second eye bolt has a block attached for the winch line to run through. The winch itself is a self locking winch (http://www.fleetfarm.com/catalog/product_detail/car-truck/towing/winches-hoists/dutton-lainson-brake-winch-dlb-1200-a) that allows you to lift and lower a load and take your hand off the winch at any time without it freewheeling. Given the cost of the winch (and the fact that I'm only using it a few times a year on the boat), I'm looking for another use for it around the garage/yard, haven't found any yet.

Here is a close-up of the forks. I drilled holes through the flat stock then cut them off mid-way through the holes to create notches that rest on the bolt that goes through the bottom of the mast. I painted the steel with POR15, which should keep it from rusting and has the feel/durability of powder coating.



The clip on the winch line attaches to a bail added to the mast about 6' up. Luckily brackish kept good notes and said the Ronstan model RF 1046 2-3/4" X 4" boom bail fit the CP23 mast well. I switched out the bolt that came with it for one that was slightly shorter, but other than that, it fit the mast well. To keep the mast from swaying side-to-side while raising or lower I made the chain/wire rope stays that are mentioned in the first 2 links, but I got frustrated/distracted while raising my mast this spring and decided not to use them (a buddy kept his hand on it to limit swaying while I raised it). Now that the mast is in the air it will be easier to adjust the temporary stays to the correct length and I plan to use them when I lower the mast.



Unfortunately my thinking that having the gin pole and the mast ride on the same pivot point (the bolt) would balance any forces was incorrect and while I was raising the mast it pulled the mast step bracket screws out of the mast step. I knew that one of the aft screws was already "stripped" and didn't have any bite on the wood, and that the second aft screw only had a weak bite, both of which pulled completely out. My buddy noticed it when the mast was about half-way up, so I lowered it back down again. I ended up drilling all 4 holes through to the cabin and running stainless steel bolts all the way through. In the fall when we take the mast down I'll remove the bolts, over drill the holes, fill with epoxy, then redrill to the correct size to protect the mast step core, but for now there is a thick bead of silicone between the bracket and the mast step to keep water out. With the mast step secured by bolts, the gin pole worked like a charm and held the mast while I attached the forestay.



Overall, I give it a B- due to the mast step bracket screws pulling out. I don't know if that was due to the design of my pole, or if it was because of stress that had been put on the bracket previously. I know there have been discussions in the past about NOT through-bolting the bracket to allow the screws to sheer away in a dismasting, thereby minimizing damage to the mast step, which makes sense. But I have to SAFELY raise/lower the mast at least twice a year, which this allows me to do. I'm willing to trade off more safety in raising/lowering with the risk of more damage dismasting. The project ended up costing about $125, and took about 4 hours. The most expensive part was the winch, and I already had some POR15 on hand, the rest had to be purchased.

[hockeyfool]

I think it is very solid and will add some 2 cents , OK ?
   consider attaching the gin pole higher up  the mast - 1-3 feet up and secure the 12" arms over the mast
  by drilling holes in ward so you can attach a bolt with washer & wingnut.
that way you can stay our of the mast step screws and still get very good leverage . Infact several
gin poles posted on the various sailor's websites do show attachment of the pole to the mast higher up
than the mast step. 

[NateD]

Moving the gin pole higher up on the mast would offer more leverage, but I think it would place just as much force on the mast step bracket. As you start winching it will still try to pull the mast toward the bow in a lateral motion before the force of the winch is translated into upward motion as the mast lateral motion is stopped by the mast step bracket. In my mind that puts just as much tension on the mast step bracket. But my mind has failed out of the school of applied geometry and physics a number of times.

[SpeakEasy]

It seems to me that locating the base of the gin pole higher up on the mast would put a lot of force against the mast at that point of contact. Maybe it would even be enough to buckle or dent the mast at that point. It also seems to me that placing it at the pivot point, as NateD did, would be the most effective place to counteract the forward force that the mast is experiencing. This is my intuitive analysis, but as we all know with physics, intuition is not always reliable.

Can you give it more of a forward angle by shortening the line attaching it to the forward bow pulpit? With more of a forward angle you would have even more force counteracting the forward force of the base of the mast, wouldn't you? Of course, you would then have to remove the gin pole before the mast was fully vertical, but by then the lion's share of the work of raising the mast is finished.

-Speak

[NateD]

Can you give it more of a forward angle by shortening the line attaching it to the forward bow pulpit? With more of a forward angle you would have even more force counteracting the forward force of the base of the mast, wouldn't you? Of course, you would then have to remove the gin pole before the mast was fully vertical, but by then the lion's share of the work of raising the mast is finished.

-Speak

I think you are right. If the gin pole was more horizontal it would offset the force more, but it would also have less leverage in lifting the mast. Next time I'm going to angle toward the bow more.

[NateD]

After thinking about this some more, my temporary stays (bridals) were very tight as I started to raise the mast, which may have contributed to the stress on the mast step bracket. After repairing the bracket I was too agitated (and rain was coming), so I didn't try to lengthen the bridals, I just had my buddy steady the mast. With the mast now up I think I can get the bridals balanced/lengthened better and still plan to use the chain/wire rope bridals when lowering the mast this fall, but as Greene (http://cpyoa.geekworkshosting.com/forum/index.php?topic=5105.0) points out in his mast raising thread, rope bridals have more give and might reduce some of the stress on the mast step when raising.

[SpeakEasy]

I have also been constructing one of these gin poles for use on Meridian. Yesterday was my first trial run. The most scary part of it was that, as I began lowering the mast, I found it beginning to drop down a bit uncontrolled for a moment. Not totally uncontrolled, but not in direct control of my cranking on the winch. And only for a split second. After the second time this happened I figured out that it was because I had wound the rope onto the winch only hand-tight. The weight of the mast was tightening the windings on the winch. After I understood this I was less freaked-out.

The biggest design issue with these is the base of the gin pole and how it attaches to the mast tabernacle. My design needs a little more work, because it is a little wobbly. When I get it worked out, I'll try getting some pictures up here to show what I've done.

Everything else worked great!

Thanks, Brackish, for sharing the details of yours.

-Speak