(New IOM owner here). I have an old Fat Boy IOM which needed some fibreglass repairs which are now complete. I have an A rig only with a groovy mast. Sails are not special and need replacing but I am looking to get on the water with what I have at the moment before I decide on a new rig/sail. Some of the rig set up is new to me (shrouds and mast ram!) but I have some knowledge of mast rake/boom angles/twist etc so set up will not be completely unknown to me. What I am struggling with is mast rake. The foredeck is angled and thereafter is reasonably flat/level? My query is how much rake is a good start? 0 to 1 degree ish?? and without knowing if the deck is level/flat to the waterline how do I measure the rake degree? I suspect you might say I need to identify the waterline and check that against the deck, but is there another way? Many thanks for your considered help! 

Not too sure that a particular number, such as 0 or 1, matters much.  Instead, some sailing will tell you where the mast needs to sit to give you the kind of helm, neutral or weather, that you prefer.  Then you would take some kind of measurement to make that reproducible.  Some folks measure the distance from bows to masthead and mark up a stick.  Some measure the angle of the mast to the foredeck.  Some do go to some trouble to find the waterline and mark that up at the mast gate or for a given position of the ram face.

Lester, thank you for the inoculation of common sense! I will get it on the water! Stuart

Assume the waterline is from bottom of the bow to the bottom of the transom. That will get you going. 

34 minutes ago, Trevor said:

Assume the waterline is from bottom of the bow to the bottom of the transom. That will get you going. 

Great Tip Trevor, Thank You!