Hi Jerry,

What is the weight of the mast ?

Many thanks for the responses.

Brian, I found that buying a single aluminium tapered tube direct from Nedal or Valmont (as mentioned in the links) would be uneconomical due to the enormous delivery costs involved so I concentrated instead on contacting UK suppliers who sourced their products from these two manufacturers. Unfortunately none of them replied to my emails with the sole exception of ALC in Port Talbot. I can't really blame them. Their primary business is bulk orders of lamp posts from local authorities etc and single orders of non-standard products are probably more trouble than they're worth.

David, I had another look at the PDF drawing of Roger Taylor's lighting column to see if I'd misread the alloy temper, but it definitely says T6.

I'm no metallurgist but I know that higher tensile steels, although stronger, can be more brittle. Does this apply to aluminium alloys, eg, is the softer T5 less prone to fatigue than the harder T6?

Jerry Stebbing wrote:The drawing of Roger Taylor's lighting column specifies 6005A T6 as the aluminium grade used, but the drawing for the 9.2 metre x 222mm x 90mm x 5mm column shows 6063 T5. I'm not sure yet whether I can specify a particular alloy for my special order pole but which would be the preferred grade if I'm offered the choice?

Jerry, 6063 T6 would be the preferred grade. 6005A T6 is acceptable. I would not even contemplate a T5 grade aluminum, it is just to soft.

I'm about to buy an aluminium conical pole from ALC for my Rustler 31's new mast but just wanted to seek advice on a few details before I place a firm order.

ALC sent me a technical drawing of the lighting column supplied to Roger Taylor for Mingming 2. It measures 13.7 metres overall but is actually listed as a 12 metre pole, with an additional 1.7 metre section that's normally buried in the ground. The lowest part of the column has large cutouts for cable entry and a service door so Roger had to discard a sizable chunk of his column to end up with a useable mast.

When I mentioned this to ALC they told me I could have a pole made to order by Nedal with almost any combination of dimensions, and with no fittings or cutouts for hatches etc. The only catch being a wait of up to 3 months for it to be made and delivered.

I've basically gone with similar dimensions to Tystie, ie 222mm diameter with 5mm wall thickness. According to the online junk rig calculator this has a breaking strength of 4975 kpm, and my boat (2.743 metres beam, 5250 kg disp) is shown as having a righting moment of 3200 kpm. I think Tystie is quite a bit heavier and with more sail area than my Rustler so I'm hoping I should have a decent safety margin. Any thoughts?

ALC have sent me an example drawing of a stock 5mm wall thickness lighting pole 9.2 metres overall with 222mm base dia and 90mm top dia. My pole will be 11.7 metres overall. Is 90mm a good choice for the top diameter?

The drawing of Roger Taylor's lighting column specifies 6005A T6 as the aluminium grade used, but the drawing for the 9.2 metre x 222mm x 90mm x 5mm column shows 6063 T5. I'm not sure yet whether I can specify a particular alloy for my special order pole but which would be the preferred grade if I'm offered the choice?

The price I've been quoted is about £900 + £300 delivery + vat which seems pretty reasonable. I haven't asked yet about anodizing but I imagine it would add considerably to the cost. I'll probably just buy the pole with a raw finish and add my own etch primer and 2 pack gloss.

In my search for a mast I also considered steel conical poles as an alternative, however the quote I received from Fabrikat in Nottingham for a 3mm wall thickness pole was only slightly lower than ALC's aluminium pole. And Mallatite (Fabrikat's main competitor) were less than helpful with their 'technical expert' telling me it would be almost impossible to calculate the loadings a sail would impose, and hence he couldn't sanction the use of one of his company's columns for use as a yacht mast. I tried reassuring him that Fabrikat poles had been successfully used on yachts (eg Paul Fay) but all to no avail, so I gave up on them.

Sourcing a suitable tapered pole for a junk rig mast  in the UK has proven to be more difficult than I envisaged but it looks like ALC could be the answer. I'll let you know how I get on.


Jerry

Stavanger, Sunday

 

Hi Phil,

That Com-pac 16 seems to be a fine little pocket cruiser. I guess you are to put the mast through the fore hatch, or?

Anyway, you are right about the partners of Frøken Sørensen: I made the mast hole as an almost tight fit and then just secured the mast with two wedges in slots. These are being held in place with a hose clamp below deck. This hose clamp also holds two more strips of wood. They are set up against the deckhead and their purpose is to hold the mast from jumping out of the step. Frøken Sørensen is not meant for OSTAR, so I find this simple method safe enough for my use. It was just a little step up from the way I stepped the second mast for Broremann ( ..see the file “20110630 Getting Broremann....”). In that boat, I made the hole in the deck a bit roomy. Then I just bandaged the mast with webbing, using carpet tape, and topped it with sports tape. That worked as well, with no noise and hardly any movement.

 

Good luck!

Arne

 

PS: On FS, the mast step was made  (intended) to be a tight fit. Still, after I while it started to move a bit here. Tapping in a couple of small, thin wedges sorted it out.