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Lowering the mast while underway

Posted:
Tue Jun 09, 2009 6:28 am
by jcalvinmarks
I have a vague notion of a procedure for lowering the mast while underway so we can go under bridges which are too low to clear otherwise, and I was hoping to solicit some input on whether or not this is a good idea.
I attach a block to the bow chainplate, run line from the forestay turnbuckle, through the block and back into the cockpit. That way I can be in the cockpit to pay out line to ease the mast down and also catch it. Then use a boom crutch to keep the mast out of the water, and motor under the bridge. Then simply raise it back up with the line in the block, reattach the forestay to the front chainplate, and off we go.
My questions are:
-Will the forestay, front chainplate, and turnbuckle handle that sort of load?
-Would a single bullet block be enough, or would a pair of doubles with a becket be better?
-Does this all just seem like way too much of a hassle, and I should just be content to stay in one section of the lake?
-Is there something I've missed that makes this whole concept not work?

Posted:
Tue Jun 09, 2009 7:57 am
by Peterw11
That's exactly the method I use to raise the mast on my DS1, when rigging the boat on the trailer. Considering the stress the forestay is under with sails hoisted, I see no reason why it can't take the stress of supporting the mast alone, especially if you have someone walk the mast up into position.
I use a single, $7, hardware store block to raise the mast, then cleat the line off on the cuddy when the mast is in position.
The only real stress on the forestay is when you have to yank on it to refasten it to the stem plate, and that's the same no matter what condition your under. The only disadvantage to doing it while underway is it has to be done from the deck. Trying to do it singlehanded would be awkward, but with help, I don't see a problem.
Rigging the mast is a PITA, even with a tabernacle, no matter where you are. Considering you have to lower your sails, derig the mast, then rig it and hoist sail again, only you can determine whether it's really worth it to get under that bridge.

Posted:
Tue Jun 09, 2009 8:29 am
by jcalvinmarks
Regarding the de-rigging of the mast, I had considered using the roller reefing function to totally wrap the sail around the boom, then use the topping lift to raise the boom enough so it isn't hitting the deck. The side stays should be able to remain attached. So maybe it doesn't need to be totally derigged? The boat only has to clear about 20 feet for the bridges that I have in mind, so it doesn't need to come down a whole lot, and only for long enough to clear the bridge.
A couple of thoughts

Posted:
Tue Jun 09, 2009 12:13 pm
by GreenLake
Let's see: you need to clear 20ft. Your mast top is approx 25ft above the water, and the movable part of your mast should be about 20ft. To lower your mast so its hight is 14ft above the deck (19ft above the water), you would need to lower it 45 degrees, more, if you need/want a higher safety margin. That's probably a bit more than you had pictured.
However, I don't think your stay, and its hardware are the limiting factors.
Question: Where's your topping lift attached to that it can hold up the boom while you lower your mast?
You could always roll up your sail and unhook the boom and place it on some cushions for the duration. That would reduce the pull on the mast and reduce the need for extra pulleys.
I'd definitely encourage you to do a dry-run of this - preferably on land. You'll quickly see whether you can hold the mast with this setup or whether you need more blocks.
Definitely figure out a way to not be limited to one part of the lake!
Good luck!

Posted:
Tue Jun 09, 2009 12:49 pm
by jcalvinmarks
The topping lift runs from the after end of the boom to the top of the mast through a block, then back down to a cleat on the mast above the tabernacle. So if the sail is rolled on the boom completely, I can raise the boom with the topping life so it's basically parallel with the mast, then lower that entire assembly. But I do see what you're saying about adding weight to the mast coming down. Maybe better to unfasten it and set it down during this operation.
And I hadn't even done the trigonometry to figure how low I'd need to go, so it would probably be just as well to lower it to horizontal and prop it up with a crutch.
So yeah, maybe this is something to experiment with. The section of lake I want to get to has no boat ramps on it, so I like the idea of it being less crowded. And it's less than half a mile from the boat ramp to the bridge I need to clear, so maybe just as well to motor out with the mast lowered, raise it once we're clear, and then lower it again on the way home and leave it there until we get to the dock. That way I only have to complete the raising/lowering operating one full time.

Posted:
Tue Jun 09, 2009 1:07 pm
by seandwyer
I just had to post this. No - it isn't a day sailer, but wouldn't it be nice if it were this easy?
http://www.youtube.com/watch?v=YbzbWScm3NM

Posted:
Tue Jun 09, 2009 1:38 pm
by GreenLake
In the video, the boom is shown supported in the mast stump below the tabernacle. There must be some boom crutch in the stern (not seen).
With a similar support for the boom at the stern, you could lower your mast, even if the boom is above the tabernacle - it should be low enough so that there's not that much leverage, and only half the weight, compared to having all the weight act five feet up the mast (if the boom is raised vertically and lashed to the mast).
Just make sure that the boom can slide on the crutch as you raise the mast.
The only difference is then that the DS mast is a bit heavier than what he has in the video...

Posted:
Tue Jun 09, 2009 5:21 pm
by seandwyer
Hey - I know this is not the same boat - but here are some good pictures to help with the idea.
http://www.com-pacyachts.com/mastendr-mastraising.html
As you can see, they have quite a crutch going on here, with rests for both the boom and mast. Also - he has a quick release mechanism for the forestay, which I saw on the DR Marine site for the Day Sailer.
http://www.drmarine.com/proddetail.asp?prod=DS803
Seems to me that the idea could be simply taken care of by using a block and line system (as previously described being fastened to the forestay) on the mast. Lower your mast into the boom crutch - the boom held to the mast with the gooseneck and topping lift. Get one of these handy quick connects for the forestay and you'll look like a pro! The ONLY advantage these boats have that I can see is that the mast step is so much higher up, making the weight of the mast more manageable. With a little dry practice I bet you could easily do this on your DS!