I have removed Flamingo's mast head and foot (Z Spars) to replace some wiring, fit new conduit and mast mount the radome. I am having considerable difficulty sourcing new pop rivets to re attach the mast head and foot. The rivets could be 6.4mm diameter but the holes are more like 7mm. Does anyone have any thoughts as to where I might get Monel rivets that big? My other thoughts are to reposition the fixings, thread the castings and use brass or bronze M6 bolts, again does anyone have any thoughts on the advisability of this plan?

Phill

http://www.rivetwise.co.uk  who may advise.
Repositioning seems a reasonable idea if the base and head casting has enough meat left.I would then go for the 6.4mm monel rivets.
An alternative might be get an aluminium welder to fill the existing holes before redrilling.I think I have heard of this method.
Since this is a problem affecting most older masts you might draw some advice on the Yachting and Boating World forums.

An option is to discuss it with ZSpars
http://www.zsparsuk.com/  (they hold most spares for pre- 2000 masts)
They use monel rivets for attaching parts to the mast. As far as I am aware the largest is 6.4.
http://tinyurl.com/pll6wsy 
- I tried a concertina one and it sheered on the fourth rivet!
For a different job I used an M6 rivnut and it worked well.

Jake

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Don't put brass anywhere near aluminium and salt water or the holes soon be a lot bigger than 7mm !

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Success,
Thanks everyone for their help. I managed to get 6.4mm Monel rivets from South Essex Fasteners at a reasonable price. No luck with Kemp and no reply from Z Spars. A DIY riveter was clearly not adequate but I had good success with a King Klik T90 (happy to loan to members if you are local to Lincoln or North Norfolk).

Phill
275/38 Flamingo