Best Bulkhead Compass?

[mika]

Shopping for a bulkhead compass. Any suggestions? I'd like one of the ones that have a built-in clinometer - need that too. Ritchie makes a nice one, at the right price. Requires a 4 and 1/2" hole and goes 3" deep into bulkhead. But I don't think I have 3" of space between the two layers of fiberglass there on my M. Thoughts?

[Paul S]

I like the Ritchie on our 26m

[mastreb]

I've got the Ritchie of which you speak. I have not yet but will be mounting it on the starboard side of the companionway, as in the photo above. There's an existing opening behind a round plastic mirror that the factory puts in to mount the winches, so it's easy to get to and plenty of room for it.

I've seen others put it below the cockpit center seat below the companionway, where its very visible as well. You can get their opinion of the difficulty of installing there.

[yukonbob]

I have one mounted in the same spot built in light but no clinometer, and it's removable. The mounting base requires a screw or three and the compass clips and locks into place so I don't have to leave out when i'm gone and no 4" hole, but that is a awesome looking setup

[mastreb]

Mine Ritchie came with a separate clinometer that happens to match the radius of my tachometer on the helm, so that's where its installed. Although to be quite frank, I can kind of tell the difference between "too flat, just right, and too heeled over" without a clinometer.

[yukonbob]

Silva 70 UN is what I have, but can't find a north american dealer.

[Tomfoolery]

I found a Saturn somewhere for cheap (was an Aquameter product, then became Danforth, now out of production), and it's, well, cheap. The gimbal system, especially the clinometer (roll) portion, but I don't really care, as I know how much the boat is heeled anyway. There's also a ubiquitous bb-in-a-window clinometer that the PO put on the sliding companionway top for my convenience, though to be honest, I don't think I've ever actually looked at it while sailing.

I mounted the compass in the hole left by a wind instrument that didn't work right, and again, I don't care since I know how hard the wind is blowing, and from where, and with my trusty Windex, I'm all sorts of informed. The compass works well enough. I couldn't find an online picture of it, but I came across some closeouts on similar units (including a Saturn), and a Ritchie for a low price. In case anyone was looking for a low price.



http://www.vikingcompass.com/149.html

[BOAT]

I assume that spot on the MAC M is perfectly lined up with the direction of the boat?? If it's not, the conpass will be off course. I assume the factory designed that bulkhead for mounting a compass, right?

[yukonbob]

Hmmm. Should always point north, unless mounted close to large metal or magnetic objects. Shouldn't matter which side or if its in the middle? Not sure what you're getting at with that boat?

[Tomfoolery]

I think he means that if the bulkhead isn't perpendicular (in plan) to the longitudinal axis of the boat, the lubber lines will be off. While the card will point north (or whatever), the lines will indicate something else. I didn't check mine with a straightedge, but my impessioin was that it was flat enough side-to-side and one side to the other to essentially be perpendicular to the long axis, though tilted forward a little.

[BOAT]

The bulkhead you mount to must be perfectly aligned with the direction of the boat - a perfect line from the tip of the bow to dead center of the transom. That would be the line of direction that the boat is pointed and extending out to infinity in front of the boat is the line that shows (theoretically) where you will be.

If the bulkhead is 90 degrees off this line everything is perfect.

If the bulkhead is NOT 90 degrees off this line it's a problem. The course indicator lines in the compass are part of the HOUSING, NOT the magnetic rotating dial. The housing is part of your boat, the dial is the compass, thus the indicator lines are part of the BOAT.

If you mount the compass at an angle that is 2 degrees off that 90 degree perfect angle, your indicator lines are also off by 2 degrees because the indicator lines are part of the fixed HOUSING, not part of the rotating dial.

I'm assuming the factory already has that bulkhead preped for that? Right? I have not had the time yet to take a laser shot of that part of the boat yet. (I have no compass yet).

[yukonbob]

Ya i finished my morning coffee and now I see what he's getting at. I read it as too far off center of the boat.

[BOAT]

Since I need a compass can you guys send me the catalog number of that compass? I will look it up and see if it has any deviation adjustments. If it does this should be an easy issue to solve. (Compass is all I used since my day was pre-gps so I have run into this before - it's not a huge problem if the compass has adjustments. Otherwise a shim thing needs to go behind the compass.

(Like as if anyone will care noawadays - the GPS has pretty much done in the compass). I guess if your out in the ocean an lose all electric you might want an accureate compass so it's worth the reserch. I'll get a laser and shoot the bulkhead today.

[Tomfoolery]

I'm assuming the factory already has that bulkhead preped for that? Right? I have not had the time yet to take a laser shot of that part of the boat yet. (I have no compass yet).

Just stick a straightedge across the companionway opening, spanning the area you want to mount the compass in. If the two sides are in-plane, it's a good bet that plane is perpendicular to the centerline of the boat, too. I can't imagine the or (or any common boat, for that matter) having both sides in-plane but not perpendicular to the centerline. Sailboats, as a general rule, are symmetrical about the long axis, or at least the outer shell is.

[JohnCFI]

Don't forget to check what's on the other side of the bulkhead, or nearby, a VHF or other electronics can have a considerable effect on the Compass accuracy.