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JoeT
08-26-2003, 11:53 PM
I'm planning for my 20' mast to pivot (like a flagpole) about 14" up from the cabin top in the tabernackle so I can go under local bridges. Would it help with the balance/weight if I plugged the bottom of the mast below the pivot pin with lead?
Thank you.

Carl Applebaum
08-27-2003, 12:58 AM
Well, sure it would help balance the weight of the long part of the mast when putting it back up, but do you really want to add a slug of lead to the boat up at cabintop level? It would have to be pretty heavy (with a lever arm of only 14") to make any difference for your purpose. It won't do your sailing stability any good. Besides, if you rig it properly--it's only 20 ft. anyway--you should be able to raise it without too much trouble. I assume that with that length of mast, the boat itself isn't huge, and the mast shouldn't be all that heavy.

Tom Lathrop
08-27-2003, 09:20 AM
Ditto. Bad idea.

Ian McColgin
08-27-2003, 10:11 AM
Since you're planning to do it alot, make a system that's really simple to use.

Firstly, the upper shrouds should be on a chainplate such that they pivot at the same height as the tabernacle pivot is. Like you could run a line from the hole in one chain plate through the tabenacle pivot and out to the other chainplate and the line is straight.

To keep it from wiggling too much, brace it with sort of auxilary chain plates like /I of /I\, if you see what I mean.

Have a way for the jib hallyard to be long enough that you can lead the hoiste to the jib tack shackle and the fall through the shackle or something and back to the cockpit.

Have a crutch top, like a U, that you can fit on any longish pole you carry anyway - oar or spinnaker pole or whatnot.

With the mast in the tabernacle and laying over the stern, uppers moderatly tight and aft lowers or back stay fixed to whatever length they turn out to be at, just push the mast up, get the pole in place normal to the mast somewhere below the spreaders and keep pushing. When it's as high as you can get that way, hold the pole with one hand while you take in the jib hallyard slack with the other and finsh getting her up with the hallyard.

G'luck

ahp
08-27-2003, 10:51 AM
Your idea does have some merit. There was a sailing barge that was used in the marshlands and estuaries of East Anglia which was called an Essex Wherry. I hope my memory serves.

Essentially it was a gaff cat rig with no boom. The mast was balanced on a tabernacle with a weight and was normally held upright with a running forestay. On approaching a bridge the forestay was eased off and the mast given a little pat and the wherry slid through the bridge.

At least that is the way Knight described it in "Small Boat Sailing". He goes on to say that the Essex Wherrys were not very seaworthy and confined themselves to sheltered water.

Ian McColgin
08-27-2003, 01:01 PM
Those barges had a slot in the deck allowing the mast, when swung up, to actually be stepped on deck.

Thus the weight was about 8'+ from the fulcrum and would do some good. Also nice and low so would do no harm.

In a deck stepped rig, the weight cannot be gotten far enough from the pivot to matter in how hard it is to raise the mast.

Paul Scheuer
08-27-2003, 01:13 PM
With the right linkage, you could counterbalance the mast with the centerboard - A natural two-fer.

JoeT
08-27-2003, 09:30 PM
Well, thank you everyone. It's always nice to correct a mistake before it's made.

htom
08-27-2003, 10:22 PM
The problem is that you don't have a good action arm, and end up with the weight where you don't want it.

So put the weight on a long L-shaped arm (one foot long base along mast, protruding arm four feet?) that you can mount temporarily, when you're raising or lowering the mast. Mount the arm, then hang the weight(s) off that long end, move the mast, remove the weight(s) and the arm, stow them below.

[ 08-27-2003, 11:24 PM: Message edited by: htom ]

NormMessinger
08-28-2003, 08:08 AM
Several hundred pounds of lead on a 14" arm should bring that mast right up. tongue.gif

A long lost forum friend from Holland, Hedzer, described a method they use there from rapid raising and lowering masts nessitated by the number of bridges across waterways. I adapted my understanding of his method combined with that described in the Grey Seal articles in WoodenBoat to come up with what I use for Prairie Islander as illustrated here. (http://www.imagestation.com/album/?id=4291389835) I can rig and launch in about 40 minutes if I have help, 30 if I do it by myself. No kidding.

Conard
08-28-2003, 08:41 AM
My system is similar to Norm's (I got the idea from a drawing in Chappelle's Boatbuilding). I made a wishbone, with legs that equal the distance from forward chainplates to tip of bowsprit. Mast sits in a crutch, lower (aft) shrouds get attached to chainplates to provide sideways stability of mast, and to prevent me from pulling it over forward. Then, pull it up just like Norm does. My boat is a L.F. Herreshoff "Prudence" with a mast that's almost 30' tall from the tabernacle, and too heavy to push up with a stick as in Ian's method.