Not for the faint hearted!
In 2003 my wife Sarah and I decided we would like to buy our first
boat. I had a little sailing experience racing Dragons and doing
a little in-shore ¼ ton crewing in the dim and distant past,
Sarah had none. We wanted an older, solid, easy mannered, sea-kindly
bilge-keeler that could take the knocks and scrapes of a novice
crew, and would be competent for inshore cruises along the south
coast.
Originally I wanted a Macwester 26 or similar. However, after looking
at several boats, the internal space was not up to Sarah's expectations,
we then turned our attention to Snapdragons. The technical Officer
of the Snapdragon Association gave such a glowing account of the
boats that we were instantly sold!
We bought Windswept, a Snapdragon 890, from Canvey Island in September
2003. The boat was home finished and launched around 1980. Although
the boat has no sail number it is possibly one of the last Snapdragons
built. The hull has the trade-mark yellow gelcoat of Johnson (?)
the last boat builders to use the moulds. The boat had been clearly
well used and needed some TLC.
The survey was unremarkable - no osmosis, several scratches and
dings - nothing of significance! It recommended the replacement
of the fixed rigging, the out-of-date fire extinguishers', gas tubing
and regulator, and to renew the outboard prop shaft bearing.
Windswept was transported, uneventfully, overland to her current
location at Quayside Marina in Southampton. This is where and when
the fun started.
Before proceeding I need to explain that I am basically a frustrated
engineer. When things do not work to my expectations I try to analyse
why and, if possible, make changes. I am not a put-up and shut-up
sort of person. In addition I was blissfully unaware of most things
boaty. This meant that I sought opinions from anyone kind enough
to offer them, and I looked at problems from first principles. It
soon became clear that there are as many opinions as people. In
the end one has to weigh the advice of others and to combine this
with one's own intuition. There are few absolute rights or wrongs.
What follows is a description of the problems and solutions that
were found.
Winter 2003.
As required by the survey and the insurers, the rigging, the gas
fittings and fire extinguishers were replaced. The prop-shaft bearing
was of the white-metal type, of which two are fitted, one to each
end of the stern-tube. These bearings are lubricated from a grease
pump. I have basic workshop tools, milling machine, lathe etc. The
re-casting and machining of the new bearings went without a hitch.
All the seacocks were serviced, the VC tar repaired, where the surveyor
had removed it, and the hull Antifouled, batteries charged, engine
serviced and tested. The boat was ready for launch.
Season 2004
All systems go. The boat was launched - and floated first-time -
no leaks! Great? No! The season went down-hill from there on.
I knew about the prop-walk issue, but had never experienced it for
myself before, this made berthing-up fairly exciting. We have a
drying berth on the lower reaches of the River Itchen. Normally
we return on a falling tide. Our berth has a following tide and
river flow in addition to a prevailing wind that blows us off. Needless
to say the prop-walk was an aspect of the boat that I wanted to
address.
The sailing itself was the most disappointing part. The performance
was so poor on all points of sail, horrendous weather helm, no pointing
ability and the lack of control during gusts. Sailing should be
a pleasurable partnership between nature, the boat and the crew,
not a battle. Southampton Water and the Solent are very crowded
and subject to periodic changes in wind speed. Over a period of
approximately 20 minutes the wind can vary by one or two forces
and swing by 90 degrees. Under these conditions we regularly rounded-up
with no control from the over-powered rudder. In busy conditions
this is not just inconvenient but possibly dangerous. We found by
experimentation that the boat was reasonably balanced when the main
was double reefed on a full genoa. The choice was simple, speed
or control, not both. We chose control - the Isle of White has never
seemed so far away! This is how we sailed for the rest of the season
in winds of force 3 and above.
We had problems with the deck gear. The furling rope jumped off
the drum if the genoa flogged in the wind. The angle of the genoa
sheets from the genoa-car to the winches was such that we regularly
had riding turns - mostly when they were least convenient. The genoa
sheets got caught between the stanchions and the bottle screws on
the shrouds. The sheets also caught in the gap between the fore-hatch
and the coach roof. The main traveller was so short that it was
not possible to adjust the twist in the main; this exacerbated the
heeling and rounding-up tendencies.
The rudder had a loose and sloppy feel. The turning arc was 45degree
to port and 100 degree to starboard.
The Yanmar 2QM15 engine was very noisy and transmitted vibrations
to the hull via the rather solid engine mounts. These were necessary
due to the in-board and out-board white-metal bearings on the prop-shaft
which prevented any lateral movement. Later in the season, as the
days drew cooler, the engine became more and more difficult to start
- yes you've guessed it! After trying everything, including having
the injectors renewed and the injector pump serviced it was time
to open the engine. The starting problems were due to loss of compression.
Cracks were found on both cylinders between the inlet valves and
the pre-combustion chambers. These had been there from the time
before the boat was purchased, but the problem had been missed by
me and the survey. The engine was cleaned and reassembled. Once
warmed, it would start and run successfully all day. We used the
engine in this state for the remainder of the season.
And… the radio reception was poor using the masthead antenna
but fine with a separate antenna - obviously something amiss with
the wiring.
I wanted to sell the boat, but Sarah, - bless her, - wanted to keep
it!
Over the next three winters the above shortcomings, with the exception
of prop-walk, were addressed. The seasons of 2007 and 2008 have
been delightful, apart from the weather. I am very pleased that
Sarah advised against a premature sale. I'm quite fond of our Windswept.
I know the boat inside-out.
The Engine.
It is interesting to the note that had the engine not failed before
the purchase it would have failed in my ownership. The reason for
this was that the cooling water galleries were almost completely
blocked by consolidated Canvey Island mud and salt. The engine had
1200hrs on the clock. The mud could not be cleared from the inspection
ports alone. The only satisfactory method was to remove the cylinder
head to gain access to the galleries.
There were no second-hand or new cylinder heads in the UK or Europe.
A cylinder head would have to be ordered from Japan with several
months delay. After some investigation I came to the conclusion
that it would be cheaper, and better, to re-engine the boat.
I did not want a raw-water cooled engine again. A heat exchanger
would avoid the need to regularly strip down the engine and would
also give the option of heated domestic water - a later plan.
The options soon settled on to a new terrestrial Perkins 103-07
engine and marinisation kit. This was purchased for less than the
price of the Yanmar cylinder head and gaskets! This engine had the
same direction of rotation, the same torque characteristic and the
same SAE bell-housing connection as the Yanmar, in addition the
size was similar. All these features enabled the re-use of the original
gearbox, propeller and engine bed, all greatly reducing the cost
of the re-fit.
The electrics of the Perkins were wired into the existing Yanmar
control panel. Only the starter switch had to be replaced with one
with a pre-heat position. The gear, governor and engine kill cables
and levers were all re-used.
The Perkins comes with an electrically operated fuel-on solenoid.
There is no place for such a device on a boat! The solenoid was
disabled and the mechanical engine stop connected up instead. It
is surprising how many new marinised engines come with such a solenoid.
I believe that once started a marine diesel engine should require
no electricity to run.
During the re-fit the original raw-water strainer was replaced by
a Vetus Water Filter. This filter has about 10 times the surface
area of the original. On several occasions the original filter had
become almost blocked after just 4 hours of motoring. I did not
want to risk overheating the new engine simply due to a blocked
filter. The Vetus has a transparent screw top that allows easy viewing
and access to the filter element. The new filter was mounted slightly
above water level so that the filter could be cleaned without turning
off the seacock.
To address the engine vibration I made-up a double universal joint
for the prop-shaft. This allowed the driven end of the prop-shaft
to follow the engine as it vibrated. The flexibility of the new
coupling meant that I could use softer engine mounts. There are
many ways to achieve the same ends, e.g. Python-drive, Aqua-drive
etc. I used the UJ solution because it was the cheapest and required
no changes to the hull.
In the first season with the new engine we experienced several losses
of power. This was finally tracked down to the dreaded diesel bug.
The fuel tank had almost two pints of the gelatinous mess. As a
precaution we now use a biocide with every fill and steam clean
the tank every winter.
Weather Helm.
The sails, though tired, had a reasonable shape and thus were not
directly the cause of the problem.
The following point is quite contentious amongst many cruising folk,
but the advice from Kemp Sails and my experience bear it out, mast
bend (some call it pre-bend). There I said it! All masts should
have a small degree of mast bend. This is usually about 2 to 3 inches
half-way up. The bend has two functions:
1. The bend ensures that the mast does not bend backwards and forwards
in a seaway. This prevents stress reversal which can lead to early
metal fatigue
2. Unless specifically requested all sails are cut with about 2.5
inches of "mast-round" to accommodate the bend.
If the mast is straight the mast-round creates a baggy sail with
a centre of effort that is moved aft - hence adding to weather helm.
The appropriate amount of bend flattens the sail and moves the centre
of effort forward.
I choose to rig the mast for 2.5 inches on bend, as directed by
Kemps (the centre of the mast is bent forward). This change had
a noticeable effect, but was not the complete solution.
A rig tension gauge was purchased. The "about right" way
of setting the tension leads to very sloppy rigging. In my case
"about right" gave about 3% strain on the static rigging.
This does not compare favourably against about 20-25% for hardened
racers, or 10-15% in my case. I found no improvement in performance
as the tension was increased beyond 10% for shrouds and 15% for
forestay. Please note that due to the different angles of forestay
and backstay the backstay must be looser. The correct tension can
be calculated with a simple bit of trigonometry.
Whilst trying to set the cap shroud tension I found that I simply
could not do it. This was due to the cap shroud not being in alignment
with the mast. In fact the base of the cap shrouds were 9 inches
aft of the mast foot. Any increase in tension on the cap shrouds
simply bent the spreaders. In a blow one could see that the top
of the main was blowing off to leeward. I have an aversion to drilling
holes in boats. It was some time before I convinced myself that
all the shrouds had to move. I used the Association's library of
technical drawings to review the original plans for the 890 and
earlier 29. There was a clear difference in the positions between
the boat and the drawings, particularly that of the aft lower shrouds.
Previously the aft lower shrouds interfered with the boom when it
was 45deg off the centreline; - this had reduced the running performance
of the boat. With the rigging in the right place and with the correct
tension, the boat absolutely flew. The rigging change was the biggest
single factor in addressing the performance and weather helm - great!
At last I had a boat!!
Whilst changing the shroud positions I took the opportunity to replace
all the U bolts, in line with advice from the Club on crevice-corrosion.
Several had the tell-tale rusty pin-holes. It is better to do it
too soon rather than too late.
The Rudder.
During the first winter I had noticed that the rudder was not aligned
with the Skeg. In fact the rudder stock was about 1 inch away from
the centreline of the Skeg where the rudder-stock enters the hull.
This meant that there was a gap of about 1 inch on the port side
and 1/4inch to starboard. This asymmetry was the cause of the asymmetric
swing of the tiller. I also felt that the gap on the port side may
be adversely affecting the water flow over the Skeg and rudder blade.
It took two years before I tackled the rudder. When I did, the following
were addressed:
1. The fibreglass foot supporting the lower bearing cup had cracked.
A stainless steel foot was made to support the structure.
2. A section of the top of the rudder blade was removed to allow
access to the rudder-stock and to enable the rudder to be lifted
out from the bottom bearing. Two removable cheeks were made to fill-in
the missing section.
3. The rudder stock was cut in the area of the section 2 above.
A flange arrangement was manufactured to connect the rudder blade
stock to the stock rising up through the hull. This arrangement
allows for the easy removal of the rudder for inspection, painting
etc - without the need for a crane!
4. The rudder blade was built-up with fibreglass to form semi-circular
leading edge and asymmetrical shape about the centreline. This was
essential to ensure the rudder was a good fit with the Skeg.
5. This point is also a little contentious. Most of the advice
I received was to the effect that I would be wasting my time, however
I persevered. A skeg and rudder blade system is similar in operation
to that of an aircraft wing, - the rudder blade acts as an aileron;
the deflected water flow generates low pressure on the convex side
and high pressure on the concave side. If the rudder blade and Skeg
combination are correctly designed most of the steering forces are
generated by the "lift" on the Skeg. If this works correctly
a relatively little force on the tiller generates a large steering
force on the Skeg. This mechanical advantage is similar to that
of a balanced rudder arrangement.
There is a problem with the shape of the Skeg on the Snapdragon
890. The leading edge is sharp and triangular in section. This shape
is fine for going straight ahead with the rudder amidships. However,
if one deflects the rudder then the flow at the leading edge breaks
up, leading to turbulence over the Skeg and resulting in very little
lift. I modelled various leading edge sections on a computer to
find a shape that combined low drag with high lift over a wide range
of angles of attack. The shape of the Skeg was modified by building
up the leading edge with structural foam and sanding back to the
required section. The foam was then covered with four layers of
woven matting. At no point was the integrity of the original Skeg
compromised as no material was removed. When the boat was returned
to the water the effect was fantastic. The new arrangement has removed
the turbulence, the loose feel, the asymmetric steering and the
effort required to steer the boat. The rudder now has plenty of
bite. It has never been over-powered since the change. The boat
now sails with very little tiller movement or effort, although some
of this is now due to the ability to balance the sails.
I ran a similar analysis on the keels. These have a very short aspect
ratio and are slim for their length. The analysis suggested that
very little improvement could be made. However, as I had decided
to copper-coat the boat in winter 2007, I decide to complete all
under water changes. To be honest I cannot detect any difference
from before the change, although when heeled over the bow wave from
the keel is now much smaller.
Deck Gear.
The furling problems were resolved by making a gate for the Plastimo
Furling system. Some systems already come with such a gate. This
was mounted at the entrance to the drum. It is now no longer possible
for the rope to jump off the drum. Whilst addressing the furling
gear all the blocks guiding the rope back to the cockpit were changed
from plain bearing to ball bearing types, greatly reducing friction.
A braid-on-braid furling line was used. The inner braid was removed
on the length of line from the centre of the drum to the cockpit.
This allowed a slightly thicker line to be used, which is kinder
on the hands.
The riding-turns on the winches were solved by taking the genoa
sheets to turning blocks near the transom. This change produces
two benefits:
1. The sheets arrive at the winch well below 90degrees to the drums,
thus eliminating riding-turns.
2. The straighter pull on the genoa/jib improves the shape and sends
the centre of effort forward thereby reducing weather helm.
The main traveller on the 890 sits in a recess by the companionway.
The original traveller only had 12 inches of effective travel, not
enough to adjust the twist in the main. As an experiment I purchased
an identical but longer section of traveller from RWO. By using
stand-offs and longer bolts I was able to mount the longer traveller
above the recess using the original holes. The new traveller stretches
across the entire width on the cockpit. The extra travel gives very
good control over main twist. We can now dump power if the wind
blows and adjust the main in light weathers.
Prop Walk.
This is the task for winter 2008. From my investigations it seems
the prop-walk can be improved by reducing the prop-shaft angle.
This has two effects,
1. The angle between the water flow and the propeller is reduced
thereby reducing the adverse torque produced by the propeller. This
has benefits in both forward and astern.
2. In astern the reduced angle reduces the water directed onto the
hull, and hence the prop-walk due to this mechanism.
For some reason the original engine and shaft were installed with
an angle of 11.5degrees, although a much more shallow angle could
have been accommodated. With a few simple changes to the current
engine-bed and the reinstallation of the stern-tube, it should be
possible to reduce the shaft angle to approximately 2 degrees.
If the changes are successful I will report back in 2009, providing
I go ahead.
Conclusion.
The basic design of the Snapdragon 890 is excellent. It will never
be as fast as a modern plastic-fantastic fin keeler, but it is by
no means a slow design. It does not deserve the comments normally
reserved for Snapdragons. I made the changes not to go fast, but
because I felt that the boat was under-performing relative to the
designer's original aspirations and my own. We normally take our
time sailing around the Solent. The changes have made the boat far
more docile and capable when the weather turns nasty. It is faster
point to point and easier to sail. The feeling of safety, comfort
and control make every trip more pleasant.
I have really enjoyed the learning opportunities presented by the
boat. I would not turn the clock back to buy a different yacht.
I am not a great communicator, nor do I avidly read my emails, but
if you have any questions I would be happy to answer them.
Please contact me at; hermes@rowther.co.uk
Sarah and Bernard Hermes, 8th November 2008.
|
