Nuts and bolts

Hopefully things don't break too often, but what sort of spares should you take with you? I always carry a box of fittings, shackles and rope - also clevis pins and rings in case I drop a pin or ring in the grass (it has happened a few times). Making sure you have these means you can  avoid missing a sailing day when something minor goes wrong.

I struggle a bit with sizes of bolts, nuts and screws. I probably have too many different sizes now, so I thought I would write down some thoughts on what is useful.

Bolts mostly come in metric sizes. On a Solo, you are most likely to use M4 (4mm thread) bolts as these fit a lot of different fittings on the boat. So get these and some "Form A" washers and a pack of Nyloc nuts to go with them. A few things on the Solo uses M5 (5mm thread) bolts, such as the pintles for the rudder. But I can't think of anything that uses a smaller size, with the possible exception of tiny bolts and screws on wind indicators or battens. Larger bolt sizes are only useful for things that go on trolleys and trailers.

Some fittings need "pan" heads and some need countersunk heads, so I try to keep a selection of both.

A note on stainless steel grades: If you can, get "A4" or "marine" stainless steel, also know as grade 316. This is the best. You can get away with A2 (grade 304), but this is more prone to rusting in a salt water environment.

Screw sizes are really confusing for me. Unlike bolts, the imperial sizes seem to persist so you are asked if you want a size 6 or 8 or 10, but those sizes are not in millimeters.

So this is my guide to screw sizes:

Name	Diameter	Useful?	Useful for...
#2	2.2mm	No
#4	2.9mm	Not really	Small mount brackets (wind indicators, burgees)
#6	3.5mm	Yes	Many fittings: cleats, shroud plates
#8	4.2mm	Yes	Larger fittings: mainsheet block mount or mast foot track
#10	4.8mm	No	Trolley/trailer?
#12	5.5mm	No	"

As for lengths of these bolts and screws, in general smaller than 12mm is not useful except for very special situations and the same for anything over 40mm. If you have 12mm, 16mm, 20mm, 25mm and 30mm you will cover most things on the boat. 

A tip for organising bolts & screws: keep them in the plastic bags they are sent to you in and make sure each bag is labelled with size and length.  Then put them in plastic ice cream boxes, one box for M4 bolt/nuts/washers, one for #6 screws and so on.

Not my most exciting blog post I know, but hope it comes in handy to some of you! ⛵