I think we can all understand your wish to avoid the noise, vibration, smell and even sporadic unreliability of petrol outboards. However, if you sail your BC23 in tidal areas, standard “3hp equivalent” electric outboards from the likes of ePropulsion and Torqeedo are unlikely to be adequate. Even on the smaller BR’s their use requires a different mindset because they lack the power and range compared to the small stinkpots to which they are allegedly equivalent (eg the Suzuki DF2.5). And they are truly feeble compared to your 6hp Yamaha.
So what are your options? There are “6hp equivalent” electric outboards that would be more suitable for a BC23 but the batteries are seriously expensive. For example, the eProp Navy 3.0 without batteries costs around £2,300. You could then add an E80 lithium battery weighing 48kg without a huge range (probably about 15nm at 5 knots on a BC23, depending on conditions) for another £1,900. Or lead acid batteries of about the same capacity but with at least three times the weight and volume for around £500. Imagine trying to take any of those home to recharge! By contrast, your Yamaha with a 12 litre fuel tank (which when full weighs just over 10kg) costs about £1,400 new and gives you a range of at least 30nm at 5 knots. Plus the ability to open up the throttle to blast your way out of trouble.
As you say, there’s not much on the forum about electricity on BC23’s and I think the above cost, weight and range comparisons explain this. I vaguely remember the very first BC23 having an electric inboard but that aspect of it didn’t get much publicity and I’m not sure that the experiment was repeated.
You won’t be able to do much about smell with your Yamaha. With care over what fuel you use, you should be able to avoid sporadic unreliability. And the noise and vibration? A while back there was a discussion about how reverberation in the BC23 outboard well magnified this and what might be done to reduce it - see
https://www.swallowyachtsassociation.org/smf/index.php/topic,1393.0.html.
There may be two other options. You could get a bigger petrol outboard - an 8 or 9.9hp with two cylinders is reputed to be much more refined but weighs around 50% more and is twice the price of a 6hp. See
https://www.swallowyachtsassociation.org/smf/index.php/topic,1742.0.html. Or you could ease up a bit - Rob J reckoned at the end of that thread that by reducing the throttle to half on his 6hp outboard, his BC23’s speed was only a little less and it made a big difference to noise, vibration and fuel consumption.
Or use noise-reducing earphones? AirPod Pro’s are claimed to reduce noise by more than 20dB.
