Tuesday, 16 March 2010

Time to Downsize

When Starcross was fitted with a new engine in 2008, they told me at Norbury Wharf that my propeller size was just outside the recommended range for my engine, but suggested that I "see how it goes" before changing it to one that more nearly matched the engine size.
I quickly found that the combination of new engine and old prop. was fine for keeping the boat moving ahead - and equally fine for stopping it - but the new minimum speed (i.e. the speed achieved by engaging forward gear but not increasing the revs) was just a little too fast. Its only by about half-a-mile-an-hour or so, but that's quite significant on a canal boat that rarely exceeds 3mph.
Its inconvenient when passing moored boats, when I often feel that I haven't slowed down enough(although I get few complaints) but its more of a problem when manoeuvring, at locks, junctions or other tight spaces and particularly when coming in to tie up at my mooring at Norbury Junction.
Space is at a premium at our moorings and my 51ft boat is expected to occupy a space no longer than 52ft, giving six inches clearance at each end. The frequent presence of another line of moored boats on the visitor moorings opposite doesn't help either.
The neighbouring boat on our mooring - taken from Starcross' counter. 
There's a similar lack of space in front.
I've become quite adept at getting into the available space without coming into contact with either of the neighbouring boats and by developing a technique of moving between neutral and ahead gear to keep the approach speed under control, but I've thought for some time that I ought to at least try a smaller propeller.
What prompted me to finally bite the bullet was that on our return to Norbury Junction from Chester we found a boat on our mooring - having been placed there apparently by mistake. Fortunately there was space in front of it (this is where it should have been left) so I had to hover in mid channel - between two lines of moored boats - whilst Hil jumped ashore, untied "Land of Green Ginger", pulled it along and re-tied it. Of course, whilst all this was going on the canal, on which we had hardly seen a boat move all day, suddenly became busy - with two boats coming up behind and an understandably nervous hire-boater coming the other way - or, rather, not coming the other way and himself hovering uncertainly just where I needed to put Starcross!
It was all resolved in the end and I even managed, yet again, to shoehorn Starcross into its space without any contact, but enough was enough and I've booked her in with Norbury Wharf for a new prop as well as some other bits and pieces that need doing (not least a loose throttle lever!) 
Norbury Wharf will be doing the job next week and I'll report how I get on in due course.

3 comments:

Halfie said...

Wouldn't an easier solution be to reduce the idling engine revs slightly?

Captain Ahab said...

Jim
What size of prop are you looking for?
The reason I ask is that I has exactly the reverse problem on WB and three years ago I replaced a little used 16 x 11 prop with a 17 x 12.
The smaller, lower pitched prop is sitting my my garage and these things cost a small fortune.
Andy

Starcross said...

Halfie,
Thanks for your suggestion, but the revs are already at the minimum setting possible.

Andy,
Thanks also, but ironically its a 17 x 12 that I'm having fitted!

Jim