Picking up where I left off in the opening ‘CLARA’s LOG’, the beginning of testing FARADAY (the first Electric CLARA) happened way back on the 10th October. You might wonder what took us so long to open the Log-book again and start reporting back on how the boat performs…
The truth is that ever since then the ground has been moving under our feet as we tested all kinds of different ways to get the best out of our chosen ePropulsion Navy Evo 6.0 (6kw). Some ideas offered immediate improvements and others turned out to be blind alleys.
In case you’re wondering, I can say right away that this little outboard has certainly turned out to be a great match for FARADAY.
The main difficulty in the early days was that the propeller couldn’t help drawing air downwards – resulting in a lot of unwelcome (and noisy) surface suction, and it was obvious that the prop just couldn’t get much serious traction from the unwanted air/water mix.
We added an off-the-shelf eProplusion cavitation plate, which improved things intermittently but was clearly not going to offer the ‘Eureka’ moment we were looking for. Tried lowering the outboard by 20mm or so….better, but still no break-through. The next move was to take the saw to the transom and lower the outboard by a further 80 mm.
Inevitably the down-side is that the leg of the outboard is further immersed – which is not great news as it’s rather ‘fat’ cross-section doesn’t have the look of something that’s going to pass through the water with ease.
The obvious solution was to turn the outboard’s leg into a ‘proper’ rudder – that would not only improve the way the boat handles – but also reduce the drag of the ‘fat’ leg when running straight under way.
We went ahead with the plan and were happy to find that the results were far more rewarding that we could have hoped for:
- No more noisy ‘swirling’ water from behind the transom.
- The ability to cut the power with no warning, and still have useful steerage way from the rudder – especially when approaching a landing stage (for example…).
While turning the boat had been driven only by a change of direction of the propeller thrust (35%), the lateral force offered by the new rudder blade tightened the turning radius while reducing forward speed at the same time during the manoeuvre.
The idyllic shot of Fraday at the head of this Log doesn’t look so good when you begin to see the chaos around the prop as the boat moves upstream from right to left.
We had been reticent to go ahead with lowering the outboard to that extent for some time because it does mean that the transom freeboard risks becoming too low to meet to the freeboard requirements of the RCD (the EU’s ‘Recreational Craft Directive’ which we have adopted as the benchmark for all safety aspects of CLARA’s design).
If this issue results in the need to add more freeboard, we will need to fit a ‘splash well’ that restores the required freeboard by adding a ‘dish’ that raises the freeboard just ahead of the outboard.
The improved handling of the boat (together with the amazingly low sound levels) was the main objective in carrying out the above and these objectives have been achieved.
We have not yet had time to re-run the performance tests since the modifications were made, but informal observations seem to indicate that the results will not be very different to those produced in October/November. This is because the big improvements in handling the boat by adding a decent steering system can only be achieved at the expense of a slight drag penalty.
The Black boat* shows how little disturbance there is from the transom after the outboard had been lowered and the rudder added.’
*You may have noticed that the Black boat and the Red boat are one and the same….it was the owner himself, Richard Stilgoe, who wanted it the same…..but different.
Steering system:
Throughout the summer it became obvious that the standard ‘Push-pull’ steering system fitted to our boats was just not up to the job. These inexpensive products are in widespread use, but in CLARA’s case it was never possible to get rid of the sloppy ‘lost motion’ those devices all suffer from. (you might see that ‘wandering’ course in the CLARA video).
The result was that we upgraded both CLARA and FARADAY to hydraulic steering systems – which immediately made life easier. Unlike the Deep-V aft sections of a planing hull, CLARA’s hull is unusually wide and flat aft – for a number of good reasons, but the downside is that the aft hull sections offer almost no resistance to lateral movement of the transom.
The result is that with a ‘sloppy’ Push-Pull steering system the helmsman is condemned to taking up the slack from side to side every 5-10 seconds in flat water.
Having now fitted hydraulic systems to all the boats built so far, life has definitely become much more pleasant for the helmsman.
Building CLARA elsewhere in the world:
In the ‘Looking Ahead’ section of our website you’ll find discussion about the idea of inviting people to build a CLARA pretty much anywhere in the World.
While we are still confident in the theory of this concept, we have come to accept that we, who have successfully built 3-4 boats ourselves, have quite a lot more work to do on the organisational side of the whole operation, and are therefore not yet in a position to be able to equipe builders elsewhere with everything they need to make the build an assured success – wherever they might be.
The learning curve has been a steep one for us so far – but we are beginning to see over the horizon how important it is (even for our own survival) to develop a building protocol that covers every possible item that goes into the mix.
It is possible that we will be able to declare ourselves fit to offer one or two trial overseas builds before the end of 2023.
As mentioned elsewhere CLARA boats are intended to be built by small and medium sized professional boatbuilding companies – rather than self-build individuals. While the learning curve is in no way difficult, it is different enough to make the first build quite challenging. Now that we’re finishing the 4th boat we’ve found that the build-time per boat keeps reducing quite dramatically – which is why we recommend that the build method is best suited to those intending to build a sequence of boats rather than just one.
The objective is that the more we refine the build techniques the less hurdles there are going to be along the way – for both ourselves, other commercial builders and, perhaps, eventually making the building process more accessible to amateurs who just fancy the idea of building themselves boat. Time will tell !
Caveat: I’m sure there are a lot of boat-nuts out there who might be reading this and who, like me, have always been fascinated by the work and philosophy of R.D.Culler – the great boatbuilder and designer from Hyannis, Mass. In his book ‘Skiffs and Schooners’ (first published in 1974) he encourages people to get on and build a boat. To spur them on he quotes another boatbuilder friend who he quotes as saying “It’s only a boat; go ahead and build it. If the first effort is a bit lumpy, so what ? There will be another much less lumpy later on”.
Inspired though I was as a young guy by what R.D.Culler (also known as Pete Culler) and his friend had to say I have to tell you now that this noble way of getting started does not apply to the build of a CLARA !
The reason is that if you start out bonding together the 700 + components of plywood that make up a CLARA then any of the ‘lumpy bits’ along the road will start to multiply in no time – until nothing fits anything anymore…. And the boat will likely never make it to the sea…
In reality the precision of the CNC cut parts is so perfectly exact that we tend to assemble anything like this steering console dry. It has tabs that fit together, so if after the dry run there are no bits left over…. You’re good to go with the Epoxy bond !
To summarise this Log, all I can say is that at this end things are evolving fast so we’ll keep publishing the way the tide flows and report back to those interested right here on CLARA’s LOG….
NIGEL IRENS
02 February 2023