Hey Jerry,
I've had two boats recently that were rigged for mast raising, a Rhodes 19 and an O'Day Mariner. Same hull, similar rig, but different deck configuration necessitating slightly different approaches.
I modified the Rhodes to have a deck level hinged mast plate rather than the stock keel stepped set up. Because of the cabin, the mast would lay forward and was pulled aft to an upright position. We used a 2x4 with a keel roller (like you have) mounted to the winch post. We added a set of "ears" on either side of the roller to keep the mast from rolling sideways. As you have pointed out, you want to keep the roller above the spreaders when the mast is attached to the hinge plate. We were not able to do this on the Rhodes and as a result when we pushed/rolled the mast into position to attach it to the hinge plate we had to lift it as we pushed so the spreaders would clear the roller. The actual raising was accomplished by attaching a long (100') line to the jib halyard shackle and with my wife pulling I could fairly easily walk aft on the foredeck and push the mast upright.
On the Mariner however, due to cabin configurations, we had the mast extending out over the cockpit and stern. We used a strut attached to the rudder gudgeons to steady it prior to lifting. The lift was done the same way, the long line giving some mechanical advantage, but it was much more difficult to walk forward as the open cockpit and companionway afforded little footing.
We have done both boats many times over the years. So, what could go wrong? Glad you asked. Once on the Rhodes the line wasn't long enough (no mechanical advantage) and we dropped the mast. Bent one turnbuckle and tore out the mast step. Luckily no damage to the mast. We always worried, for good reason, of the shrouds, stays, and various lines catching on bits of hardware, passing pedestrians etc.
It seemed that our biggest fear was the lack of lateral stability during the operation. We usually had the main shroud loosely attached but it still seemed a bit precarious.
Just a couple thoughts. Be sure that you can run a straight line, string perhaps, from your mast step up and over your roller. On the Mariner we had a problem at first in that the mast when attached in the down position and on the stern support would interfere with the top on the companionway hatch. We had to greatly increase the height of the stern support to get a straight line to the mast step. We quickly found that only the upper shrouds could be loosely attached to provide lateral support. The two lower shrouds due to their chain plate location in relation to the mast step caused them to bind when raising or lowering.
I think my biggest fear with the telephone pole of a mast on my Dolphin would be establishing good lateral support during the entire 90* arc when raising the mast. How about that monstrous mast on the Corsair? Yowzer!! Webmaster Note Mike is referring to an online Utube demo https://www.youtube.com/watch?v=eqsbJn475_g. The Corsair uses the temporary lines attached to the folding deck loops as the shrouds are not an option. A solid sliding A frame support would in my mind be ideal. Since I have a mast with an external track some type of modified sail slide MIGHT work, but I'd be afraid of tearing the track off. One set up I've seen uses a short piece of spinnaker pole track with a car and an A frame that hinges on deck. Rides on the forward aspect of the mast, is easily removed, and gives what appears to be good support.
Well I'm sure you're bored to tears and as I am a hunt and peck typist, this took three hours to type, I'll say goodnight. Keep me posted as to your thoughts on the subject.
Mike
ps Here's some interesting pictures/article I found on the web. The imbedded link to the Tanzer site has some nice detailed drawings. More than one way to skin a cat, or so it seems. http://www.boicey.com/sailboats/mastraising.html
pps Here is an interesting thread posted in an Australian forum.http://www.trailersailerplace.com.au/phpBB3/viewtopic.php?f=2&t=11370
I like the idea of the rope bridle as described. Since it's too darn cold up here to do any serious work, I'm left with searching the internet for ideas. I may actually make a half or quarter scale rig with 4x4s and try the described rope bridal idea. As my wife will attest, our biggest concern in past mast raising/lowering events was the relative lack of lateral stability.
I dug out the set of Farrier trimaran plans I have and while Ian Farrier did a masterful engineering job, as can be seen on that Corsair 31 video, you really have to get all the pieces lined up perfectly. Might be tough to do given the deck layout of the Dolphin.
