As said mine is 2.5 kg and in salt, but not the depths that some have been talking about.
Love the idea of casting a toy plane, guess where I am going tomorrow; TOY WORLD !!!
Thanks for the comment, on the downrigger, have to say I am pretty happy with how it turned out. I have made a few changes since the photo's were taken that have made it a lot better. First I have removed the clamps that were holding the reel on and replaced them with hex key bolts, nylex nuts and backing washers making it a lot stronger.
Second, where (for the want of a better description) the reel to the T that the "fishing rod" section passed through was only a few inches long and the rest sticking out was 2' long, I have now reversed it with the reel section now several feet and the rod only a few inches. By doing that I reduced the amount of leverage on the kayaks stability and that of the downrigger itself but also brought the reel forward so it is almost right next to me when seated and a lot easier to use, specially with my stuffed neck and back.
Another little trick I was playing with was creating a mixed bubble stream & tuna oil slick by creating a venturi siphon. It was a little awkward to play around with due to the 6 meters of tubing to the surface but once setup and going worked quite good, mind you there is a lot of drag on the tube.
All I did was, drilled a hole through an old cupboard door knob then stuck some 6mm plastic tube (6 meters long) into it with silicone, I then attached that to the weight so the tube end and knob was facing the rear. The pressure drop as the water passes over and past the knob creates a vacuum and pulls air from the surface as well as the tuna oil that I just squirt into the tube, I clip only a very short leader into the downrigger release so the lure hangs of the end of the bubble/oil trail.
A lot smaller tube with small funnel on the end or better still a special hole in the weight would have even better results but depth will be greatly restricted due to the drag on the tube. You would also need a really large reel so you can actually wind the tube and line on together and hope the tube does not squash closed when rolled on.