It's quite a simple, logical water system on Honey Ryder, but logic evaded my helpful, well meaning little hobbit friend as he tried to do a job we have performed several times together like clockwork, but, alas, working alone he forgot when to do what and why and it all went a bit tits-up.
what happens every four months or so is that our accumulator needs a bit of air adding to it to keep the water pump churning away at a nice leisurely Brrrrrrrrrr Brrrrrrrrrrrr, rather than a staccato sounding Brr Brr Brr Brr Brr
its an easy job; switch off the water; switch off the pump; find a bicycle pump; open a tap; attach the pump to the valve on the accumulator and pump two or three times to remove a little bit of water; switch off the tap; resume pumping with the bicycle pump until it goes firm. switch on the water, switch on the pump. Open a tap and see if you have the pressure right by listening to the pump, hopefully purring away like a happy cat.
It is best to avoid this sequence: switch off the water, go and open a tap, switch off the tap, go and switch off the pump, come back and open a tap, pump the accumulator continuously until you get confused why it wont go firm, go and close the tap, come back and resume pumping, get bored of that, switch the pump on, water on and then panic and switch it all off again when the pump makes a very bad B B B B B B B B B B noise. try pumping the accumulator some more, try as many different combinations of the above possible. give up and go out for a meal with partner, look sheepish on arrival home and then wait until midnight just before going to bed to spring the good news to the unsuspecting.
after a few choice cross words, I knelt on my knees with my head pointing into the water pump hole, praying to the boat-maintenance-god that we hadn't actually permanently fucked anything and hoping that my weekend wouldn't be spent visiting chandleries for replacement parts. several minutes more of sitting on the bed looking at the stricken pump, accumulator and dismantled panels with head to one side like a dog that just heard a funny sound, I resolved to go to bed and have a little think about it.
32 hours later the answer came to me, let the bloody air out of the accumulator. Eureka.