mjf
Well-Known Member
After a brief discussion on here last year I have finally got around to fitting this new bow thruster propeller.
A report on the antifouling performance on the hull follows separately.
The ‘kit’ consists of a new five bladed shaped prop (old type was 4 blades – pitched, not shaped) which looks not unlike the shape used on an HMS nuke submarine although these have many more blades. A new adaptor that fits the shaft, new locator/locking pin, new locking nut with nylon thread + washer , plus a replacement anode.
I got this at SIBS with the intention of fitting same over at the Cowes sealift during the winter. Anyway this was not to be so when I lifted out for a ‘shampoo, shave and haircut ’ in my home marina last Friday; whilst the boat was in the slings this job was done.
Typically as the holding time in the slings was limited things went wrong at the start.
Previously when ‘on the hard’ during antifouling etc I have changed the thruster anode – simple enough just remove the Allen key screw and the anode falls off the prop nut that holds its position. This time I could not get the Allen key in – some marine hardish growth had rudely taken up home in the key hole! High pressure water blast sorted that family out and I tried again. This time key fitted but I could not turn it – too tight. Sod it! After a struggle it moved, time was becoming short now. Removed the bolt but the normally loose anode was stuck fast on the nut. Incidentally it was only 5% eroded after 13 months in the water. Again HP blast and much banging and teasing still no movement, bear in mind this is actually quite a tight place to be banging about as any sideways action has to be contained in the narrow confines of the tunnel. Anyway, finally removed the anode by a double claw pincer movement using a couple of paint tin openers……
Removing the prop nut was yet another test of resolve as SWMBO will attest with bruised hands from holding the wood wedges that had to be deployed holding the prop against its vertical drive housing.
Fitting the new prop was a doddle after this – except I managed to cut SWMBO finger quite badly when I said “ hold the prop whilst I tighten the nut with this large socket ratchet with extension” I had not checked she was using the wooden wedges but her hands directly on the blades!.......
Once refloated – time to try. This was actually quite difficult as during the operation the wind was blowing exactly side on as I approached the hoist 15 knots with gusts to 30. The thruster is now certainly much much quieter so I assume less cavitation.
It certainly seems to ‘grip’ better – before, you would operate it and only after a couple of seconds did you notice any action. Now it’s almost immediate – this is excellent for arresting a swing without overdoing it.
What I need to test now is improved power. Frankly I have always taken the view that in F3 or below it was not needed and in anything stronger it was underpowered.
The wind during my brief test was too gusty to gauge but I think there is an improvement as there does appear to be more grunt – it certainly sounds more effective.
I would be interested if others have fitted this and their findings????
A report on the antifouling performance on the hull follows separately.
The ‘kit’ consists of a new five bladed shaped prop (old type was 4 blades – pitched, not shaped) which looks not unlike the shape used on an HMS nuke submarine although these have many more blades. A new adaptor that fits the shaft, new locator/locking pin, new locking nut with nylon thread + washer , plus a replacement anode.
I got this at SIBS with the intention of fitting same over at the Cowes sealift during the winter. Anyway this was not to be so when I lifted out for a ‘shampoo, shave and haircut ’ in my home marina last Friday; whilst the boat was in the slings this job was done.
Typically as the holding time in the slings was limited things went wrong at the start.
Previously when ‘on the hard’ during antifouling etc I have changed the thruster anode – simple enough just remove the Allen key screw and the anode falls off the prop nut that holds its position. This time I could not get the Allen key in – some marine hardish growth had rudely taken up home in the key hole! High pressure water blast sorted that family out and I tried again. This time key fitted but I could not turn it – too tight. Sod it! After a struggle it moved, time was becoming short now. Removed the bolt but the normally loose anode was stuck fast on the nut. Incidentally it was only 5% eroded after 13 months in the water. Again HP blast and much banging and teasing still no movement, bear in mind this is actually quite a tight place to be banging about as any sideways action has to be contained in the narrow confines of the tunnel. Anyway, finally removed the anode by a double claw pincer movement using a couple of paint tin openers……
Removing the prop nut was yet another test of resolve as SWMBO will attest with bruised hands from holding the wood wedges that had to be deployed holding the prop against its vertical drive housing.
Fitting the new prop was a doddle after this – except I managed to cut SWMBO finger quite badly when I said “ hold the prop whilst I tighten the nut with this large socket ratchet with extension” I had not checked she was using the wooden wedges but her hands directly on the blades!.......
Once refloated – time to try. This was actually quite difficult as during the operation the wind was blowing exactly side on as I approached the hoist 15 knots with gusts to 30. The thruster is now certainly much much quieter so I assume less cavitation.
It certainly seems to ‘grip’ better – before, you would operate it and only after a couple of seconds did you notice any action. Now it’s almost immediate – this is excellent for arresting a swing without overdoing it.
What I need to test now is improved power. Frankly I have always taken the view that in F3 or below it was not needed and in anything stronger it was underpowered.
The wind during my brief test was too gusty to gauge but I think there is an improvement as there does appear to be more grunt – it certainly sounds more effective.
I would be interested if others have fitted this and their findings????
