Originally Posted by Andy
The easy answer is, to take the wheel off, clean and re-grease once a season along with your regular maintanence stuff. So that it comes off lots easier ....
If it works, there is a fault. This is a morse taper. It's purpose is to jam solid! However, in practise, I agree because marine streering wheel bosses, in general, are crap quality. This might also explain how water can enter the taper.
If you want to do it without damage and especially if you feel you may need to do it at sea, a bit of preparation at the outset will help, although it can be done later. Drill and tap the boss each side of the centre hole. Make a wee strap, with two clearance holes using the same pitch as the tapped ones, which can be put across the top of the shaft. Tighten a couple of screws into the tapped holes to draw off the wheel. It should be done in manufacture in the first instance.