quickly. For Blackstar-I we chose to use a custom PTFE face seal at the base of the drum. The relationship between seal effectiveness versus friction on the drum would emerge as our single biggest challenge. The critical lubricating film these seals rely upon for their performance was also clearly being compromised – the sheer volume of water in direct contact with the winches causing localised emulsification. Suspecting some degree of
capillary action delivering water ingress, we experimented with different types and grades of oil, alternative versions of lip design and seal pressures. It wasn’t quite 100 per cent but we raced every day and helped our teams deliver good results on the Great Sound. The television coverage of
AC35 from Bermuda was widely acknowledged as spectacular and the commentary team certainly had a host of innovations to discuss during the event. Thanks to the keen eyes of Ken Read, it also provided Stayinphase with its first exposure to a wider audience. Some of the performance gains
were significant enough for us to want to keep going and fortunately it wasn’t long before we received other enquiries about new winches. The Alegre TP52 sailing team were the first to commit and support us on our first multi-ratio version…
BLACKSTAR-II For our next effort we shifted away from using a face seal to explore rotary shaft seals, as this winch would require more protection due to the need for both self-tailing and top-handle input capability. And with more components to protect than the single-speed version, our constant lubrication system now required further development. A higher-capacity pump was
designed in plastic, with an indented area of the winch base working as the sump; from the pressure port the pump lubricant is distributed via internal oil galleries to the critical areas of the winch. However, during an early proof
test of the new winch drum design we encountered our first significant
Clockwise from above left: the first pair of Blackstar-II winches was installed on the TP52 Alegre; pressure-fed lubrication is delivered to the centre bearing sets via the small stainless steel inlet pipe that can be seen to the right; a lubrication check is carried out on the bench on the original Blackstar-I prototype; a cutaway section through the Blackstar-I; the radial displacement (exaggerated for clarity) of a Blackstar II drum is modelled using Finite Element Analysis
problem. We had underestimated the cylinder stress and related wall thickness required to prevent distortion under load. In this case, deformation of the drum side wall. A detail FEA analysis was
undertaken with Mark Evans at Coupland Bell, which gave us the understanding we needed to get past this hurdle. FEA remains a very powerful tool in the right hands… Senior engineers describe it as a validating tool, a proven means of confirming ‘manual’ calculations. With such serious consequences related to a drum failure at sea this was an early wake-up call for us. In the Blackstar-I the drum anti-
backwind defence was a ratchet set between the drum and main housing. This presented a relatively safe defence against back-winding, the downside being it was a little noisy and, as it was further away from the central axis, it produced a higher level of friction than we had hoped for. Despite our desire to find a better concept it was with some reluctance that we incorporated this ratchet into Blackstar-II. Into the heart of things… The
second and third speed ratios are configured in a unique way in this winch and it wasn’t until we had begun testing that we began to fully comprehend what we had created. Following dynamic tests of the prototype at a 2,200kg line-load, we were alarmed to find deformation on the third speed gear set that should not (in theory) have seen the sort of load required to cause that damage. So something clearly wasn’t
functioning as anticipated. Patrick Hopson and I pored over the device for a couple of days, slowly tracing how the loads were passed through
the gear sets. Stunned! Mapping out the load paths in the epicyclic 2nd/3rd gear hub unit, it appeared that we had accidentally produced an innovation in self-locking capability which, if true, would allow us to totally remove our front-line drum ratchet. Confirmation of this was obtained from an independent external engineer and we set about uprating the gears and removing all unnecessary ratchet components. Subsequent tests at 2,500kg
confirmed we had what we were searching for all along… a safe anti- backwind that is also super-quiet. A ‘Phoenix from the Ashes’ moment. Full-power runs on our test rig
delivered smooth performance from a four-man input, with Futek data acquisition and logging equipment suggesting efficiency gains that were ranging between 12% and 22%. The subsequent 2018 season
was a huge learning period for us. Not without moments of soul searching, but also some amazing moments including seeing Team Alegre take third place and top owner-driver in Cascais at the TP52 World Championship. We can stand back now and say it
has been successful, for sure, but I don’t suppose I made it easy for myself. We had attempted to achieve a tremendous amount in only 18 months and we took some solid knocks along the way. So, as always, my thanks go out to those who helped us, with special mention to Paul Nichol here at Stayinphase and of course Team Alegre. We are excited about our next
design sessions, taking all we have learnt so far towards E-Blackstar-III. Beyond normal limits!
Jon Williams, Stayinphase q SEAHORSE 75
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