Fitting A Wind Generator To The Mizzen Mast

closereach <no_reply@...>

Having lived on board my Super Maramu 2000 (299) the past 22 months,
mostly on the hook, and sailed 21,000+ nms, I decided to investigate
putting a wind generator on the top of my mizzen mast. There are not
ANY wind generators that will supply all the SM's electrical needs,
and research showed that the only two makes that would make any
significant contribution were the Air Marine 403 and the Kiss.
However, weight is a factor, and I chose the Air Marine 403 which is
half the weight of the Kiss.

Because I did not wish to get the mizzen staysail halyard tangled in
the blades, I decided to mount it on the very top of the mizzen mast,
where it would be out of the way. Amel kindly supplied me with a copy
of the mast top blueprint, and I had a stainless plate made up that
matches the mast top plate, and welded the support post to it with
suitable bracing. Note that if you wish to replace your mizzen
halyard with the wind generator in place, you will have to cut a slot
in the plate to allow access to the sheaves.

The 403 worked well up there, even down wind, but the vibration from
the unit caused an unbearable resonance in the mast, which made the
generators use at night, and even at certain RPM's during the day,
impossible to live with. However, after some 6 months of trying
various cures, I have come up with a solution that works well.

I discovered a company in England called AVA Limited that specialize
in anti vibration mounts. Yes there are many on the market that
consist of a rubber block with a stud bonded to each end, but these
would not be suitable in case of failure. The AVA mounts are fail
safe as they have a bolt through the entire assembly. They are made
of die cast aluminium, so they do need spraying with zinc chromate
primer then a good quality marine paint before use. Also they have a
two bolt flange bottom fitting which would make them difficult to fit
to the area of the mast top flange that protrudes outside the profile
of the mast.

I got around this by making up 4 aluminium pieces of 1/4" bar that
were tapped with three holes. Two holes take the short fixing bolts
from the bottom flange of each vibration mount, and into the centre
tapped hole I screwed down a bolt that would attach the whole unit to
the mizzen mast flange. To make matters even better, I put a strip of
1/4" rubber under each bar before bolting the vibration dampers down,
sleeved the 10mm bolts with fuel tubing where they pass through the
bottom plate, and put a further piece of rubber under the washes of
the 4 bolts that attach the dampers. All bolts were locked with
Locktite 270 locking compound.

The wind generator is now never switched off, and is hardly
noticeable under sail at all, and makes but a faint singing noise in
the aft cabin at night. I would point out though that Air Marine are
again testing their Air-X model which will be considerably smoother
and quieter in operation. After much dialogue with Air Marine, they
have asked me to test an Air-X on my mizzen top. From what I have
seen so far, the new model will be worth waiting for. There are some
RFI problems to be sorted out before I get the test model, but it
should not be long now. They have gone away from using blade flexing
to limit the turbine's speed, and are now using more rigid and
quieter blades.

Of course, one wind generator will not solve the Super Maramu's
thirst for electrons! I have also fitted 2 Solarex 120W 24V solar
panels to the side rails just aft of the genoa car adjusters. The
combination of all three works well. Under sail in sunlight, I need
an apparent wind of 15 knots to equal the electrical demand, and at
night 24 knots (radar on). In the tropics, I now only need to run the
generator once a day, usually in the evening. My only regret now is
that having such reduced generator time, I should have bought a
bigger capacity water maker!

I did leave Crusader in the Bahamas for 2 weeks on the anchor with
the freezer running but the fridge switched off, and returned to find
the batteries fully charged. It's this freedom to leave the boat for
sight seeing and visits home that got me interested in an alternative
power supply.

AVA Ltd can be found at:

Unit 1, Monkton Park, Farnham Trading Estate, Farnham, Surrey, GU9
9PA, England
Tel: 01252-733040 Fax: 01252-722958

What you need are 4 x AL30 Specials-25NAT M10 Core Price 9.56 GB
Pounds each.

They are specials in that the top fixing bolt size is increased to
10mm as the original bolts on the AL30 units were a bit on the light
side for the application.

Modifications to the bow thruster, hot water system, anchor wash and
speaker systems will follow when I get a moment!

Good sailing

Ian Shepherd

Amel Super Maramu 2000 # 299 "Crusader"

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