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Subject: [worldcruising] Re-engine
From: John Easteal (jeasteal@XXX.XXX)
Date: Wed Aug 16 2000 - 06:52:22 EDT
I'm looking for views on engine selection.
My Westerly Corsair (36ft) has a 15 year old well used Volvo 2003 which
needs a new gearbox in the short-medium future. Given the costs of the
gearbox (repair or renew) and a variety of concerns about the present engine
I'm seriously considering replacement. I guess that I'm really getting the
boat ready for my retirement (not yet infortuneately).
Volvo and Yanmar both work to a formula of 4HP per ton. A Corsair is around
7 tons(empty) which leads to 28HP. I know two owners with replacement
engines, one has a Volvo 2030, the other a 2040, both now have 3 blade
props. These are about 28 and 38 HP respectively. both appear to be happy
with their choice.
Calculations (See WOA Software page, I use Excel 2000) show an expected top
speed of 7 knots for my present engine with a 3 blade prop combination. With
my 2 blade 17 x11 I can actually achieve 6.5 knots down hill with a
following wind in a flat calm, 4.5 - 5.5 knots in any sort of lumpy sea.
Maximum revs 2600 rpm for an engine with 3200 quoted top speed.
I am more concerned with maintaining a reasonable speed in real sea
conditions and feel that the present performance could usefully be improved
on.
I do sail most of the time but when time is short and the wind is dead
ahead, I want a little more stick.
I could install a new 28 HP and change to a 3 bladed prop, or go up to the
38 HP, also with a 3 blade prop. The difference is about £800 but I want to
be sure that I have made a sensible choice for performance. In the scheme
of things (installed) the difference is probably only about 10% in price.
I am looking for experience with engine change / boat size / performance. I
want a sea boat not a river boat.
Any comments?
john
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