The 70P Compass is the standard deck compass that fits most sea kayaks with a compass recess bowl (the exceptions being the "Danish Style" kayaks by Current Designs which only fit a Ritchie compass). This compass has been around for decades and has been branded as Brunton, Nexus, Comcast, Silva. Currently it comes with a Silva nameplate/bezel. The 70P Dash Mount Compass is a thing of beauty that makes your kayak look complete and expedition ready. Seriously if you are still using an orienteering style compass with a needle while kayaking, it is time to upgrade to a direct reading deck compass -- no more waiting for the needle to stop moving while your kayak spins around and faces the wrong way. Note: With an orienteering compass you can turn the outer ring of the compass card to adjust for the declination so when the needle is lined up correctly the compass reads True. With a direct reading compass like mariners use there is no needle; it's the compass card that is magnetized and pivoting. So the good news is you don't have to line up the needle to use your compass; the bad news is there is no way to make a deck compass read True. All your compass readings with this compass will be magnetic directions. There are many ways to deal with the declination (or as navigation charts call it, "Var" which is short for Variation - the angle between magnetic north and true north). We recommend converting your courses (and other bearings from from the chart) to their magnetic equivalent; that way life is simple when steering by your direct reading deck compass. To mount the Nexus 70P compass to your kayak (kayak must have a hemispherical compass recess, and not be a Current Designs kayak), you'll need to drill four small holes for the self-tapping screws. The screws and a drilling template are included with the compass, however the included screws are longer than desirable for kayaks so we recommend replacing with shorter ones (See below). The screw holes are generally tight enough to make a waterproof seal, but it is good practice to cover the inside tips of the screws with caulking or Aquaseal adhesive anyway (which in addition to making a secondary seal will also protect you and your gear from getting cut by the tips of the screws inside the kayak). When the mounting screws are loose the compass ball can be turned. As a final step in installing the 70P Compass, turn the compass ball until the gold lubber line is lined up with the center of the compass logo on it's bezel (the "L" of SILVA) then tighten the screws to hold it in place. Recommended Accessory: Install Kit for 70P Compass (sold separately). This Kit includes a 1/8" thick foam rubber gasket that fills gaps between the deck and the bezel helping prevent things from catching on the bezel and breaking it off. Also includes screws of the proper length to replace the extra long ones that come the the compass. Otherwise you'll need to find a good hardware store to buy: stainless steel #4 self tapping pan head screws that are 3/8" long. Or file each of the original screws to this length. For composite (fiberglass etc.) and thermo-formed kayaks use a 5/64" drill bit and run it in and out a few times to slightly oversize the holes and wiggle it to make the holes a bit funnel shaped; for roto-molded PE kayaks use a 3/32" drill bit.
