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downeast450 01-31-2012 12:06 PM

Mast tabernacle project
 
Anybody tried this? Are there reasons I shouldn't?

Rapidly rising costs of a boom truck, scheduling issues involved and the accumulation of my exploratory designs and models have brought me to the "jump off" point for my mast tabernacle project.

I would like to be able to raise and lower the mast on Tundra Down, our Islander 28, myself. The Norsea 27 DVD makes it look straightforward. I have built a mast base mockup and located the point of rotation on the mast section. I have a cardboard tabernacle mockup. It has been test fitted to the deck. It seems to work as expected. I will add an aluminum tube through the mast with an id of 1" for the ss bolt and cheek plates to each side of the mast base where the bolt will swivel. The tabernacle will be built to the width of the cheek plates. I will shorten the mast to accommodate the added thickness of the tabernacle base.

I am trying to decide how to route mast wiring and am thinking, having it exit the mast rather than be involved in the action of the pivoting base is prudent. I will eliminate the current access plate, it will be in the way of the pivot bolt, and replace it with one that provides an exit for the mast wiring. I would appreciate any ideas about this. Exiting the mast, where? The base of the mast is a busy place.

Shortening the uppers looks like a simple thing thanks to STA-LOK. Adding longer turnbuckles to the chain plates and a couple of shackles isn't rocket science either. I will add two eye pads to give me the purchases I need aft and figure out how to "capture" the base with the mast resting on the pulpit rail. I may need to strengthen the pulpit or build a crutch and brace it to the pulpit. The video of the Norsea 27 shows a nylon trailer roller mounted on the pulpit and that looks like a good solution. Keeping the down, resting, mast from rolling on its side will require some thought. I want this to be a solo operation if possible.

I also need a plan for storing the mast above the deck. We hope to travel the Erie Canal on TD. It will be nice to carry the mast overhead. I also want to use the mast as our winter cover's ridge pole.

Aluminum or ss for the tabernacle? I am thinking 5/8 tempered aluminum?

I am going to spend a day on this this week. Winter is wasting.

It should pay for itself in two storage cycles and free me from the boom truck! Ha!

All suggestions are welcome.

Thanks Down

GaryHLucas 02-26-2012 07:04 PM

Down,
My boat, an Etap 26 has mast tabernacle that also contains the mechanism for the retractable keel, and the mast sits on a pivot pin, so it can be easily dropped. I took it down by myself using a simple A frame made from two 8 foot long two by fours simply lashed at the bottom to the toerails. Then a guy to the bow, and the mainsheet with a sling over the spreaders did the lowering. My mainsheet is only four part and a little too short. I got small handheld worm gear puller to put it back up.

I'll note that my mast has a second hole in up much higher, and I realized once it was down that the hole was to to attach it to the tabernacle when in the down position.

Gary H. Lucas

downeast450 02-27-2012 08:34 AM

Gary,

How does your mast wiring exit your mast?

Down

GaryHLucas 02-29-2012 12:07 AM

Quote:

Originally Posted by downeast450 (Post 837301)
Gary,

How does your mast wiring exit your mast?

Down

The pin through my mast is about 1-1/4" diameter and the mast is reinforced by cheek plates where the pin passes through. So the pin carries the entire load and the bottom of the mast is completely open for wiring and the halyards.

Gary H. Lucas

downeast450 02-29-2012 04:08 AM

Gary,

I am surprised to learn that the mast rides on the pin. In the only video I have seen of an operating tabernacle (NordSea 27) the pin seemed to function as a pivot and the mast base came to rest directly on the tabernacle's base plate, on the deck. The pin is still in place and I am sure helps secure the base of the mast, fore and aft, but the pin rides in a slot in the tabernacle so it can move up as the leading edge of the base of the mast (partially cut away to reduce this radius) rotates through the 90 degree sweep as it rises. I did not understand that in the vertical position the load was entirely on the pin.

Could you share a photograph of your mast's base?

Down

GaryHLucas 03-01-2012 12:51 AM

Quote:

Originally Posted by downeast450 (Post 838136)
Gary,

I am surprised to learn that the mast rides on the pin. In the only video I have seen of an operating tabernacle (NordSea 27) the pin seemed to function as a pivot and the mast base came to rest directly on the tabernacle's base plate, on the deck. The pin is still in place and I am sure helps secure the base of the mast, fore and aft, but the pin rides in a slot in the tabernacle so it can move up as the leading edge of the base of the mast (partially cut away to reduce this radius) rotates through the 90 degree sweep as it rises. I did not understand that in the vertical position the load was entirely on the pin.

Could you share a photograph of your mast's base?

Down

Down,
As I said the pin is very hefty, it would easily support the entire boat without bending!

I don't currently have a photo of the tabernacle, and I've been in California for most of the past month. However as soon as I make it home I'll get a picture. Might be a couple of weeks yet.

Gary H. Lucas

downeast450 03-01-2012 07:23 AM

Gary,

Thanks,

Down

downeast450 03-07-2012 07:38 AM

Re: Mast tabernacle project
 
Progress!

The starting point for this project was and is an excellent DVD produced by Ed and Ellen Zacko titled, "How to Raise Your Mast Yourself". Ellen and Ed Zacko Sail around the world in the Lyle Hess designed NorSea 27 Entr'acte. Their sailing adventures are an inspiration. I have contacted them directly and they have answered all my questions more thoroughly than I could have hoped.

Here are "details" they have shared in response to my questions:

1/4" aluminum plate for the tabernacle
1/2" ss pin
Their mast does not ride on pin but sits on its base on the tabernacle. A Pin supported mast would be better if maintaining sailing tension while lowering was important. It is not one of my requirements
Wiring exits mast about a foot off the deck
Wiring couplers are Bulgin Buccaneer Connectors

Ed elaborated on many other considerations, too. He does a very through job of explaining how it works in the DVD.

Buy iinformative and entertaining Zacko DVDs - read below to learn more

Thanks to Ellen and Ed and all my friends at Sailnet I have run out of excuses to delay making the necessary hardware and adding cheek plates and a pin location to the mast. Learning a CAD program would be helpful I suppose so I could just send a file to my fabricator! It never ends!

If we get the mast and the tabernacle ready and installed changing the rigging will happen after stepping. That means the first test of the system will be taking the mast down before haul out. That will be a little anxious!

Down

skygazer 03-10-2012 03:19 AM

Re: Mast tabernacle project
 
O.K., I've not done a mast that size but just thinking about it, I wonder if you should measure from the mast hinge location to the transom (assuming you will lower to the stern, i. e., hinge is towards the rear), and compare that measurement to the half way point on the mast.

In other words, how far beyond the end of the boat will the balance point of the mast be. If the balance point is beyond the end of the boat, you must push down at the hinge end hard enough to counterbalance the mast and relieve the pressure on the hinge pin. That downward pressure will be added to the weight of the mast at the rear support point. Try to make sure that your support point is strong enough and that you are able to put enough downward force to balance the short end of the mast at the hinge. In other words, have help the first time.

I'm not being discouraging, I think it's a great idea. I just want it to work, and want you to be prepared. How will you support the mast when it comes down, will you be on land or water? Let us know how it goes!

downeast450 03-10-2012 03:45 AM

Re: Mast tabernacle project
 
Sky,

I appreciate your observation. I will be lowering the mast forward, using the boom as a "lever". It will overhang the bow rail and will be top heavy requiring a support at the bow rail and a "capture" device at the mast step to hold the base down as it gets moved ( rolled I hope ) aft. I have a Rhodes 22, also, which gives me a little experience with a small tabernacle. This one will be a bigger challenge. I will share the design if it all works and I have high expectations.

Down


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