How to install and set up a navigational marine compass in your sea kayak
“Skill’d in the globe and sphere, he gravely stands
And, with his compass, measures seas and lands.”
Unless you typically paddle small inland lakes and rivers, or stay close to shore and can easily rely on visual landmarks, a compass—and the skill to use it—is an invaluable navigation tool, and installing one in your kayak is easy. These instructions are for mounting the popular Silva Marine Compass; if using another model, refer to the compass’ manual as you go along.
Project Parts & Materials List
- Silva 100P deck compass or similar
- Drill with various bits
- Silicone, AquaSeal, or epoxy putty
- Phillips head screwdriver
- 6-10 feet of fishing line or kite string
- (4) 6-32 x 1/2″ Phillips head, stainless-steel machine screws
- (4) 6-32 stainless-steel nuts (nylock: with internal locking nylon inserts)
- (4) #6 stainless-steel flat washers
- (4) #6 rubber flat washers
- Nut driver, wrench, or socket wrench to fit nuts
- Pocket hiking or orienteering compass
The compass recess in nearly all modern sea kayaks is designed to accept flush-mount marine compasses such as those made by Silva, Brunton, Ritchie, Suunto, and others. Although nearly all such flush-mount compasses made for use on sea kayaks will fit the standard recess found on most boats, confirm that the one you’re considering will indeed fit. In addition, there are also surface-mount compasses for kayaks lacking a molded recess; some such models simply bolt onto a flat area on the foredeck, while others are quickly attached and detached with bungee cords.
In installing my own flush-mount compass, I opted to use machine bolts and nuts instead of the supplied self-tapping screws, for what I believe is a more solid installation, and to avoid the sharp protruding screw tips from snagging drybags and hands inside the bow compartment. Some paddlers simply apply a protective dab of silicone or epoxy putty to the screw tips after installation.
NOTE: It’s imperative that any hardware used on or near a compass be non-magnetic, or you won’t know your nuts from north. Use stainless steel, brass, aluminum, or plastic hardware for mounting your compass, to avoid confusing magnetic disturbances to your navigation device. If you carry on your foredeck a spare paddle which uses an older-style, spring-loaded, metal push-button ferrule mechanism, it too may create magnetic interference. My trusty old Werner Camano throws my compass off by a whopping 30 degrees, so check yours.
I used 6-32 stainless-steel (SS) Phillips head screws with matching SS washers and nylock nuts. I also used rubber washers against the underside of the deck to prevent water intrusion. The bolts for my particular installation were 1/2-inch long, as this was just enough length to go through the compass mounting plates, the boat deck, and still accommodate a rubber washer, a flat washer, and a nylock nut on the back side, with no extra length to snag drybags. Your deck thickness may vary, so purchase bolts a bit longer and then cut them down to length or apply dabs of putty.
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Remove the compass from its package and dry fit the entire assembly into your deck recess to ensure compatibility. The Silva 100P compass included a nice little self-adhesive drilling template, which I briefly paused to admire before casting aside. After years of messing around on various projects with misshapen, homemade cardboard patterns, I’ve learned that the best template for a part is often the part itself. So lay the black plastic fascia plate in the compass recess as straight as possible and drill through one of the corner holes with a bit large enough to accommodate the bolts you intend to use (9/64″, in my case), and right through the deck. (If using the included self-tapping screws, employ the same method but instead drill a pilot hole of the size specified in the instructions, to accommodate the screw threads.)
Immediately slip a bolt through this first hole to hold the fascia plate in alignment while you drill the next hole. Slip another bolt in this second hole and repeat for the remaining holes. Remove the fascia plate and bolts, and set aside.
The brass mounting plate has undersized holes made to accommodate the included self-tapping screws, so it must be drilled a bit larger if using 6-32 bolts. Gently remove the brass plate from the compass globe and use a pliers to flatten the protruding tabs on the four corner holes in the plate, then enlarge those holes using the same 9/64″ bit.
Return the brass plate to the compass globe, drop the assembly into the deck recess, and lay the black plastic fascia plate atop the whole works. Slip all four bolts through the fascia plate, the brass plate, and the kayak deck; you should have about 1/4 inch of bolt protruding into the cargo compartment. Slip a rubber washer, followed by a flat stainless washer, onto a bolt and hand-tighten a nylock nut to hold it all in place. Repeat for all four bolts (or loosely install the self-tapping screws, but do not yet tighten).
It’s irrelevant at this point that the compass does not read “0” (zero) or “N” (north), as it’s unlikely that your kayak happens to be lying on your lawn at precisely due north. But it’s imperative that the compass’s lubber line(s) be oriented precisely along the kayak’s longitudinal axis or keel line. (Lubber lines are the 1-2 stationary markings on the globe body itself, NOT the floating dial). So tautly stretch a section of heavy string along the centerline of the foredeck, from one known centerpoint near the bow to another centerpoint well behind the compass, and tape the ends in place. Most kayaks have some sort of deck fittings or other features which can be assumed to be situated on the deck’s centerline, so use these. The longer this string is, the more accurate your alignment will be.
Because you have only hand-tightened the compass, the globe can still be rotated in its housing and properly aligned before locking it down. Peering down from directly above the compass, move your head until the alignment string bisects the center pivot bearing of the compass card with the numbered graduations, then gently rotate the globe until the lubber line(s) essentially disappears behind the string, or are perfectly aligned with it.
The compass should now be properly aligned with your kayak, and you can tighten down the four mounting bolts or screws. After doing so, confirm that the lubber lines are still properly aligned.
A new, quality deck compass can be assumed to be accurate out of the box, but you never know how it may have been manufactured or mishandled during shipping, so it’s a good idea to compare it against a known good compass.
Lay your kayak on the ground, oriented roughly due north. Using the same or longer centerline string as before, lay a pocket orienteering compass or similar on the rear deck and align this compass body with your centerline string. Check the needle of this compass to see what bearing it indicates, then gently pivot the entire kayak and pocket compass until it indeed reads “0” or “N”. Your kayak is now aligned with the planet. Or, at least, with the planet’s magnetic poles, which is all we’re concerned with here. Without jostling anything, go up to the foredeck and check that the deck compass indeed reads “0” or “N”. If so, congratulations, you are ready to venture out upon the high seas.
If not, and if your deck-compass lubber lines are indeed aligned with the kayak, then your deck compass may need correcting. Contact the manufacturer or retailer for more information.
Keep your expensive and vital compass clean, protect it from hard impacts, and store it away from electric motors, stereo speakers, and other strong magnetic fields. When tripping, be sure to avoid packing magnetic objects such as campstoves, flashlights, radios, etc. near the compass. Keeping it out of direct sunlight during storage will prevent hazing and crazing of the transparent plastic of the globe.
The orientation of the compass globe and lubber lines should be casually checked at least annually and before any big trips, as rescue practice and other rough handling can knock a compass loose in its mount. You can easily realign your compass as outlined above, or occasionally check it against those of your paddling partners while on the water. Carefully point your bow at a distant landmark, such as a lighthouse, radio tower, or distinct mountain peak or lonely tree, and see what bearing your compass indicates. Ask your paddling partner to do the same and compare bearings; if they do not agree, one of you has a whacky navigation device, and we cannot have that. Someone needs to go home and re-align his lubber lines or calibrate his compass.
Periodically check the deflection of the compass; lay the boat on the ground or in work cradles and observe whatever graduation mark the lubber line indicates on the rotating card, say, “270”, or due west. Move a magnet or a large screwdriver close to the compass to gently make the card rotate off that mark by 30 degrees or so, and hold it there a moment until the card stops moving. Quickly move the magnet away several feet and observe the card; it should gently and smoothly swing back to settle on the original mark. If, instead, the card pauses or ‘hangs up’ somewhere along the way, or settles on a mark several degrees off the original mark, this is an indication of inconsistent deflection, and it is unreliable for navigation. Contact the manufacturer for repair or replace it with a new unit.
“… Measures Seas and Lands”
A quality deck compass, properly installed and well cared for, will provide many years of safe and happy kayaking. On open-water trips, it’s a crucial and necessary piece of navigation equipment and, combined with your own knowledge and skill, it will keep you and your little boat on a true heading.
Paddling.com’s “Compass Basics for Kayaking”
Paddling.com’s “The Marine Compass”
“Fundamentals of Kayak Navigation”, by David Burch
Get the Silva 100P Marine Compass here
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Dear, I am in China, i have two SeaBird Victory HV kayaks. was i have find out that you have Kayak Deck Compass. Could this size be use on SeaBird Victory HV kayaks?
If yes, please let me know how much? with deliver to China GuangZhou?
Thank you and looking fory our reply!
with best regards,
Molly, it appears that such a deck compass can indeed be used on the SeaBird Victory HV, and should fit with no problem, following the instructions in my article.
Such compasses may be purchased here.
Or, you could use a removable compass which attaches via strap or cord:
I don’t know whether any of those vendors will ship to China, nor the costs for shipping. You may also try Amazon China.
Stainless hardware attracts magnetism, try your refrigerator magnets on it and see. I got all brass hardware at Lowe’s.
A Sidebar About Stainless Steel
The Encyclopedia Metallurgica will tell you that stainless steel is non-magnetic, but a visit to the local hardware store with a strong magnet in your pocket may convince you otherwise. Although stainless steel contains iron, its magnetic properties are ostensibly nulled when nickel is added to the alloy. But poor distribution throughout the part, or even the cold-forming of the material into nuts, bolts, and especially washers, can indeed lend some level of magnetism to it. Not an admirable quality for hardware intended to mount, you know, a navigation compass!
In the course of my extensive field research and empirical scientific sampling of off-the-shelf SS hardware (ahem), I found that about 80% of the contents of the little bin of bolts at my neighborhood True-Value had a discernible measure of magnetism, and I was able to drag them around on a flat plastic surface with my alnico magnet. These I returned to the bin while carefully setting aside the non-magnetic examples. I was able to apply the same methodical process to the nylock nuts and washers before staff threatened to call security.
Certain grades of SS such as those found at marine suppliers may have lower magnetic qualities, but check them before using. I also learned that a metal part can be de-magnetised by laying it on a block of wood, oriented in an east-to-west fashion, and striking it with a hammer 50 times. Considering that I needed four bolts, four nuts, and four washers (plus a few spares), I determined that my time was better spent working on my offside roll, so I just bought the non-magnetic hardware.
Super helpful instructions, Jeff. I originally was going to write to ask about those little metal tabs. I drilled the holes in the brass plate without straightening them, as suggested, though it would have made the job a little easier to have done so. I bolted (I used the same hardware you did) the whole thing together with the tabs still in their original factory condition. Was that a mistake? Everything seems to be holding together ok, though I haven’t been out bashing around yet in my boat. Will my boat blow up or sink?
Also, I wish I’d read all the comments before finalizing my hardware selection. I did do a quick check of the hardware with a magnet, but then had to replace the original screws (I got flatheads rather than pan heads), and forgot to test the new batch. However, when I checked the installed Brunton compass with a handheld compass at N, S, E, and W, the readings between the two were the same, so I’m thinking I’m OK. But those tabs…..
Geoffrey, you should be OK with the tabs undrilled. As I recall, the reason I drilled the holes larger was to prevent the metal plate from buckling when running the larger bolts thru them. As long as this didn’t happen to you, you’re probably just fine.
As for the hardware, it would depend on how strongly magnetized it is. As long as your deck compass closely matches your accurate handheld compass, you’re safe to go paddling!
Hi Jeffrey, thanks for your instructions! I will put this in my Wilderness Tempest 165. I assume the tabs help keep the compass in place. Why do you suggest to flatten them?
I have just like you a set of 6×32 stainless machine screws with vinyl nuts & rubber washers. They do attach to my (strong) magnet and the magnet affects the compass at about 2ft away. But holding the screws up near the compass doesn’t do anything at all. Should that not mean it’s totally safe to use these to mount the compass? And even if there’s a slight magnetism, I thought that one on each corner should balance it out anyway…
Lianne, sorry for the late reply but I’ve been away …
I don’t recall exactly what purpose the brass plate with tabs serves, and it may even be unnecessary when using your own mounting hardware. If you decide to flatten the tabs, simply squeeze them flat with a large pliers, or flatten them with a hammer on a block of wood …
Yes, sounds like the SS hardware bits are so slightly magnetic as to not be a concern; I’d use them, and simply double-check your compass’ accuracy before each season.