[C320-list] Bolt size specification needed, please

[Graeme Clark]

Hi everyone - someone once said of Britain and the USA that we are two nations divided by a common language! I need help  because my boat was built in the US (obviously!) presumably using US nuts and bolts but over here in Britain we have been metricated for some years so I am having trouble finding equivalent bolts to replace my engine mount mounting bolts (ie the ones that hold the mounts to the bearers that are glassed into the boat)

I found that I can use a 14mm spanner to undo them - its not a perfect fit, I guess the actual size across flats is a little bit less than 14mm. They are coachscrews that look roughly like this http://img.auctiva.com/imgdata/1/8/2/9/8/6/7/webimg/732578281_o.jpg

Because I am replacing my engine mounts with a different mount that has a thicker base, I need a slightly longer screw to penetrate the bearer to the same depth. I assume the bearer is wood  and i want to obtain screws with the same thread pitch and diameter so that I dont end up cutting a new thread over the old, which will greatly weaken the attachment.

I am guessing that catalina will have used a stainless version of a standard off-the-shelf coachscrew available in pretty much any US hardware store -  can anyone tell me what the specification is?

Thanks

Graeme
‘Jaskar’, #366, Falmouth, Britain