Thierry, if Peter wouldn't mind you forwarding his email to me (webmaster@gmail.com) we could add his ideas to the site.

Yep, I already asked him if it's OK.

I edited my post above and replaced "gin pole" with "derrick".

Cheers

Thierry

Robert Groves wrote:The masts on Easy Go are flagpoles from Ewing. They are working well and show no signs of fatigue to this point in time, at least when I left Lunenburg in the fall. The poles came with a standard base that clamps to the pole. With a little ingenuity I think they could be adapted to some sort of tabernacle base. The forward mast is six inches and is quite noticeably more flexible than the seven inch main mast.

Good (cool) Morning Bob,

Now that business is starting again I can contact them for prices and drawings.

What sizes and series did you take for Easy Go?

Cheers

Thierry

The masts on Easy Go are flagpoles from Ewing. They are working well and show no signs of fatigue to this point in time, at least when I left Lunenburg in the fall. The poles came with a standard base that clamps to the pole. With a little ingenuity I think they could be adapted to some sort of tabernacle base. The forward mast is six inches and is quite noticeably more flexible than the seven inch main mast.

David Tyler wrote:The well-proven tabernacle type, for alloy masts, is to make a fork and tongue hinge between the mast and another piece of tube, above deck level. For a 5" tube, this might have a 1" hinge pin,  joining a 1 1/2" thick tongue and a tight fork, both machined from 5" alloy bar. Then you get another piece of tube which is a sliding fit over the 5" tube, and about 4ft long. It is this that gives you the strength, not the hinge, which only comes into play during hoisting and lowering. To lower the mast, you slide the outer tube up so as to expose the hinge.

I read a discussion of this method, never seen a drawing of it.

What I don't understand is how you slide the tube over the hinge without having a 2'-long cutout in the back of the tube.

Also how do you get a piece of tube that is tapered like the mast to get a perfect fit.

I wonder also about sliding the tube up at the end of the season, especially if it's tapered.
Regular sliding up and down? Vaseline?

If neither the pole nor the sliding piece are tapered how do you get rid of the play and have contact full length?

Cheers

Thierry

David Tyler wrote:

Thierry Msika wrote:http://www.ewingflagpole.com/specifications.php

They seem to be available in Dartmouth, NS. Would the 25' pole architectural series OK for a 25m² sail?

Metal is T6 alu.

There is also a tilting flange :
Tilt Hinge Anchor Shoebase
This mounting allows the pole to be lowered, although not with the ease of a counterbalanced tilt anchor shoebase. The anchor bolt strength is the same as for the counterbalanced and fixed anchor shoebases.

Has anyone ever used a horizontal flange system as a tabernacle?

Thanks

Thierry

I've had a look at this website. I couldn't find any drawings of the hinged bases, but I would think it most unlikely that this would be suitable for a mast. First, whatever the mast is bolted down to has to be the same strength as the mast. That means at least another piece of tube of the same size, with some extremely good design and manufacture needed to make the join. I don't think I could suggest a design that would guarantee the same fatigue life as the tube. Remember that they are only reckoning to hang a flag up, not a large sail. If you want a tabernacle, a more conventional arrangement should be used, with a hinge fitting clamped onto the tube. There must not be any holes, or welding, anywhere near deck level. This is the major cause of failure of unstayed alloy masts.

Ewing give bury of 10% for a ground set pole, so they are in agreement with PJR thinking.

A 5" tube with .156" wall, 6063T6, is enough for a boat of 1 ton displacement. I don't know whether 25ft is long enough, you might need the 30ft length.

Thanks David for taking the time to look at Ewing.

I thought of using the bottom 4 feet of another mast with the same base put upside down so as to protrude a foot above deck as a support for the mast. I'll have to talk to the company for that as the price might be prohibitive. Also I don't know if two bases can be bolted together.
I also looked for technical drawings. I guess I'll have to get them from the company.
Yes I will need a 30' mast if keel stepped and might just scrape by with a tabernacled mast.
Don't you think a large flag flapping in a windy location 12 hours a day, 12 months of the year would subject a mast to much more fatigue than a daysailer even sailing a lot during the season?

Can you suggest a proven design for a tabernacle? I am thinking of Speedwell or Oryx but I don't know where to look.

Cheers

Thierry