ricka

Does salt on and in the fabric make any difference to it being for marine or motorcycle?

Bio Magic additive from Burnsco

You wouldn't need one.

I would prefer the boat next to mine has, like mine, a gas certificate as well as EWOF

Thanks Fish - good pics and explanation. Counts me out though as I don't have a strut.

Ah huh - brilliant then that's the problem! and I will replace the cutless bearing. Last time I removed it with a slide hammer cutting a slot in it first with hand held hacksaw blade. The boat has the prop in an aperture which is a bit of a bugger cos to get the shaft forward enough to remove the bearing the engine has to be lifted and moved forward or possibly get away with removing the gearbox (uncharted territory). Thanks for the offer of the puller might take up you up on that - the size is right. Would you be able to send a pic and I can quickly see if it will be of use due to the sm

Yes but all those are isolated eg there are no mixed metals in contact with each other under the water. Fastners are isolated, bronze though hulls are isolated, s/s rudder shaft is isolated from bronze bearing at the lower end. There is an electrical path with resistance from the prop shaft to the stuffing box and cutless bearing - not sure why except perhaps because they are close to each other and the salt water is conducting. The only thing that isn't isolated is the prop and shaft which are dissimilar metals and the prop degrades over time but will last for 10 years or more

Getting bit off topic here because what I would like to know is and my original question is .....has anyone seen scale/calcification build up on the prop shaft inside the cutless bearing? But re the anodes rule - number one is don't mix metals under water - lots of info at Waitemata Woodys https://waitematawoodys.com/2015/05/15/electrochemical-damage-to-wood-the-marine-version-of-leaky-homes/

Wooden carvel boat. Anode = even more trouble - its cheaper to buy a new prop every now and than fix the stern timber area from degradation

The only other thing is that researching this I realised the cutless bearing has a brass shell part number which will be in contact with the copper stern tube and if it really is brass it will be breaking down. (5 yrs old) No anode fitted anywhere. So will replace with a phenolic one and have a good look at everything at that time (now soon)

Prop is fixed 3 blade. Prop speed in good condition. Recent water blast. As the noise goes away with use there is a variable. The only one I can think of is hard growth on the shaft bearing surface.

Thanks for input..Checked alignment, deadwood cutless bearing= bronze tube with rubber bush. The noise goes away with motoring use.... Is hard growth on the shaft possible?

Is it possible to have scale/calcification build up on the prop shaft inside the cutless bearing that causes a vibrating/chattering noise from that area in forward and reverse that goes away with use? Ok at low revs worse at moderate to high revs. Prolonged low speed use makes the noise go away. Boat = 36’ timber yacht, 5 yr old / 150 running hour rubber bushed kind of cutless bearing with normal play and 2205 s/s shaft also 5 yr old, bronze prop, no anode, run in fwd and rev gear 2 x month minimum for 30 minutes

Not all 12M berths measure 12M some can take a longer boat and not overhang which is what you need

I had Ashbygas check and certify my system-recommended