New Years day saw the final demise of the original 1987 38HP Thorneycroft diesel engine in my 43 foot Bruce Roberts ketch. In frustration, I contacted James Mobberley of Marine Transmissions NZ; we discussed the various options available to me, but concluded with James’s recommendation i.e. to fit a new 54HP Yanmar motor and a new propeller etc to match the increase in horsepower this new engine would give.
The installation was done on time, within budget and with proper tidy-up.
There were, however, persistent vibration problems with the prop shaft and the new propeller itself. James confirmed that all the stated specifications had been met and sought second opinions from other Yanmar specialists with the same result. Nevertheless, he accepted, without question, that something was amiss and worked consistently and cheerfully to put it right.
It took numerous sea trials, several lift outs and many consultations before it was concluded that the new prop was cavitating. The keel on this ketch is hollow around the stern gland; it was flexing with the power of the new Yanmar, thus the vibration. James finally solved the problem primarily by re-fitting my old propeller (re-pitched) which, according to all calculations and specifications underpowered the Yanmar but which, in practice, solved the problems to my entire satisfaction. We lost ½ knot in speed.
While there was never any doubt that James Mobberley's installation met all the stated requirements and most of the second opinions of experts and the old hands, he worked on the problem until it was fixed, and at no extra cost.
I would be pleased to recommend him and his company for any work of a similar nature.
