I had a Suunto compass which fitted on a bracket on the front Kayaksport hatch cover of my previous Taran 16 (photo below). I know some people had concerns whether in rough conditions the capture mechanism might cause you to lose it - but over five years that never happened to me. I found the front hatch position for the compass perfect for me, as although it is a fair way off (especially in the Taran 18) it is in your line of sight when paddling, so no refocusing or looking down. It was also easy to take on and off to avoid some scally nicking it off the boat when it was on the van etc. One of the downsides of that compass, as with most others fitted on kayaks is the lack of a light for use at night. I had some small glow sticks that could be put underneath the Suunto compass above the bracket, but have to be honest that they were awkward and I never ended up using them. When I sold my previous Taran 16 the new owner wanted to keep the compass so I needed to find a new solution for my two new Tarans (16 & 18 - lucky boy that I am...).
I went for an Autonautica C3 as the Suunto was no longer available. Its a bit larger than the Suunto & initial impressions are that the display is a little finer & may be more difficult to read & follow. In addition the Autonautica compass seems lightly damped, so we'll see how that affects things due to the regular motion of the boat & bounce in harder conditions.
This compass has a 12v inbuilt light, but experimentation indicated that it was satisfactory at 9v which gave better battery options. You can see I've fitted a switched battery holder which is secured to the hatch cover using velcro.
One thing that I investigated was the magnetic interference from the battery, and this is not negligible, & is position, orientation & battery type dependent (NiCads I tested having a much smaller effect than Lithium - maybe due to the metal casing around the NiCads - although battery life should be better with the latter - will report back later). I think I eliminated the magnetic effect of the wiring by using a twisted pair, as well as the fact that the current draw for the light is very low.
Although I have moved the battery as far away as possible on the bottom of the hatch cover, and oriented it for least effect, in practice when I use the compass I plan to velcro the battery pack down on the front of the front bulkhead as far away from the compass as possible. I'll also investigate using a piece of shielding material.
Disadvantage of this approach is the need to switch the light on in advance, or have a buddy do it. This also shows how careful you need to be with what you put underneath your compass in the hatch..... Anything electronic (e.g. GPS, phone) regardless of whether it is switched on or not can have an effect. As with storing your compass - keep it away from any electronic devices, especially those with magnetic speakers, even when you aren't using it to avoid the risk of repolarisation. Looking at sailing advice they suggest keeping anything that may cause magnetic interference at least a metre away from the compass.
Will report back on real life use, battery life & shielding in due course.
Anyone got any special insights or experiences of this?