Kevin,
Click on Members in toolbar on top, than technical articles in dropdown, than manuals. Choose MK1 Manual and go to page 21 that is the only thing I see about the masthead, not really a blueprint.
 

Hi, 

I'm in the same position. Just picked up our 1988 C36 and need to replace the wind instruments as they are not working. The old ones is Datamarine, so I am looking at the different options for replacement. Which one are you planning to go with? Please share your experience!

Thanks,

Daniel

I am going with a GARMIN wireless wind transponder and installing a Garmin 2000 backbone. I intend to leave Raymarine and go with a more compatible 2000 backbone.  I can use GARMIN or B&G instruments on my Pedestal. Pratical Sailor did a 2000 compatibility test with transponders and instruments and GARMIN was rated over Raymarine. 

I purchased a Raymarine ST60 Wind sensor to mount at the masthead, but before I go up there I want to be prepared. Can anyone supply the answers to the following questions?

1. Is the masthead unit mounted with screws plus washers and nuts on the underside of the plate? Or is it mounted just with screws? Are the mounting holes tapped, or will sheet metal screws be sufficient? Do I need to take a tap and die set up with me in addition to a drill? 

2. Yes, I will make sure to prevent bimetallic corrosion.

3. Any of you folks on the east coast who pull your sticks every winter, can you help me out here, perhaps with a photo and personal experience?

Any advice that you can provide that can help me make only a single trip up the mast will be much appreciated.

Are you asking about how the transducer base is mounted because you're replacing a defective one or because you're doing a new install?

A new install. Presuming the plate at the masthead will have no transducer mounting holes whatever.
 

Self tapping #8 using a 4mm or 5/32" or #24 drill bit.  That's the easy part.

An 8mm hole for the cable.  Good luck feeding this down the mast with the stick up.
 

Any photos of the top of the mast out there that might help me envision the transducer mount and cable feed strategy? Surely someone on the east coast will be pulling their stick soon? Thanks for any help you can offer.

Larry,
I've uploaded two pix of the top of the mast of #2211, so it should look the same as yours.  Note that this owner chose to have one wire come out of the top of the masthead fitting (small black wire for wind instruments?) and two wires come out of the side of the mast (white vhf coax + larger black wire for ???).  Hope this helps.

Thanks, Tom. That's helpful. 

The white wire in the photos is clearly a coax, the small black one is for a wind sensor. Not sure what the large black one is for, but I'll guess anti-lightning static dissipator?
 

See if this helps.

Thanks, Bill.

Whatever you do, make sure all your wires go down the mast through the conduit. If not, the slapping wires will drive you nuts, especially trying to sleep. Our new wind instrument cable was too big to fit, so out tech has to replace some multi wire bundles with individual wires. I've been told that you can use wire ties to hold cables off the mast sides, but never tried it!

Will do my best to route wiring via conduit, for sure. What I'd like to know before I begin drilling through the top cap to mount the wind sensor and route the wind cable is the following:

1. What does the inside of the masthead look like? That is, where are the sheaves, the halyards, the conduit, and any other critical items I need to be aware of as I drill. Anybody got a photo of the guts of the masthead?
 

Larry,
I've had the masthead off my MkI mast, and from memory, it looks exactly like the diagrams on page 24 of the pdf of the C36 MkII owner's manual, which is on this site.  Two pairs of sheaves, one forward and one aft, separated by an aluminum plate about 1/8" thick.  There isn't a ton of room between the sheaves and the top plate of the masthead, so be careful drilling into it so as not to cut a halyard.  The conduit (conduits?) is pop-riveted along the forward side of the mast, offset slightly to one side (I can't remember if it's port or stbd).  You can tell exactly where it is by looking for the heads of the pop rivets on the outside of your mast.  Getting a wire into the conduit without a messenger line, and with the masthead in place, is just about impossible. It is possible to take the masthead off with the mast in place (I've done it, and it would take a few pages to describe), but it is not easy.  It would be much easier to drill a hole in either the top plate or the side of the mast extrusion, drop a weighted messenger line, and then pull up the wire from below, with triple sets of wire ties every 3-4 feet.  I've done that for a radar cable, and the cable was quiet inside the mast, suspended between the wire tie tails.  The wire ties did not interfere with the halyards.  Hope this helps.

I went wireless . Did not want to run another wire and it works great

Thanks. That's very helpful.