Timely topic for me and minim! Thanks!

She's a 21' Coromandel with a hinged and sleeved alloy mast, such as many Coromandels and other small junks have.

I first raised the mast only a few days ago. No problem handling the 21' tapered mast, hinge-pin and sleeve solo, afloat in mild conditions. Tape to retain the sleeve, vigilance to not lose the pin...

When the River Deben got choppy later, noises from within the loose (gap of 3mm all around) sleeve told me this thing will grind and knock itself to bits eventually, and sailing will be stressful.

The former owner used little wooden wedges at the sleeve-top. I put a set in, but the hinge itelf kept knocking and grinding, gyrating in the gap at mid-sleeve. Then the wedges started blowing away. A plastic half-pipe (house gutter) filled the gap better, and spread the point-of-contact load, somewhat. I'm going to pursue this approach.

I'll try to fit a pair of half-pipes, to fill the radial gap the whole length of the sleeve, which I must ensure remains able to slide. 

There's a conical alloy fairing-piece to help battens & parrels pass the unfortunate step. The fit of the sleeve on the collar at its lower end is pretty good.

The glass-epoxy bulking-up method seems another good option. Maybe later.

If absolutely no wobble, slight possibility no slide...

(photos: experiment at top of sleeve; bottom of sleeve at collar; mast stub & style of hinge)

Cheers, Kurt

Hi Graham,

the fiberglass looks good. I think that short sections of a PVC drain pipe epoxied to the mast may work on 100mm and 150mm OD aluminium mast sections. The sliding section sizes I have come across seem to give about 10 to 12mm clearance on the mast sections so the 3 to 5 mm wall thickness of the PVC pipe would leave 1 to 2 mm clearance to allow it to slide. PVC has a certain amount of natural lubricity so should help the parts to slide.

 David, I suggested a couple of tangs on the bottom of the sliding section that the topping lifts could be attached to in order to lift the sliding sleeve, this would also hold the sleeve in place while the mast was raised and lowered. Do you think that would solve the problem you talked about in your last post? Also one advantage of the sliding sleeve is that it allows the rig to be lowered below the hinge. This means that nothing has to be loosened or changed on the parrels etc in order to lower the mast. This is particularly useful with an Aerojunk rig and I am thinking of using this kind of arrangement on Little Gypsy Girl (if she does not sell first!)

Anonymous, thanks for rotating my sketch upright.

Mark Thomasson wrote:

One thing I have no experience of is how easy it is to slide down the sleeve - I take it that it has to have sufficient slack so that it will not bind, yet not too much that there is a wobble.

This is the thing that I've found difficult with it, when helping Robin, and I can confirm your conjecture, Mark. The outer sleeve and the mast, both being aluminium, are not the best of pairings for sliding, and so there has to be some slack - but not too much. Also, the sleeve is heavy enough that it would be difficult to raise the mast single-handed, keeping the sleeve up above the hinge while pushing the mast up. Maybe the sleeve can be taped in the raised position, otherwise it always seemed to me to be a two person job. Once the sleeve is lowered over the hinge, the upper end has to be taped, so that the parrels don't stick on the step on the way down, so that the reel of duct tape is to hand anyway.

This hinge + sleeve arrangement is neater than a tabernacle, for sure, but I prefer the tabernacle in the form that I've mentioned, with the pin at the lower end and the opening of the 'U' facing aft, for greater ease of operation. I have it on my 12ft dinghy, I had it on an 18ft dayboat, and I think it scales up to larger boats quite readily, as it was the method used in the Yorkshire and Northumberland Cobles, in sizes up to at least 30ft.

Thanks David,

I knew someone would help out and put it in its correct location!! One day when I am not quite as busy as I am now I will have to try and figure out how to do this sort of thing correctly!!

Any comments? I have not actually built one but went through the whole design exercise before finally deciding to use a wooden mast and tabernacle on Gypsy Rose.

Thanks, David.

PS. I note that the sketch did not get copied over so posted it again