My insurance renewal , almost due, went up 20% compared to last year but when I shopped around I only found one cheaper. And that , with Saga, was only by a couple of quid so I am sticking with my present insurer this time . It seems I had a good deal from my present insurer last year.
What I did find by shopping around was significant variations in prices.
I will not say what I am paying as it includes UK coastal so not fair to compare with the great majority on this forum who are inland waterways only. However it is quite clear to me the premium is calculated on the value of the boat (and not its length) with consideration also given to where the boat is usually kept and the cruising range.
I do think premiums for boat insurance have gone up greater than inflation and quite a lot more than some other insurances.