T.A.P.

Thanks all, of course a second option is to stick with hydraulic (the hull and superstructure design mean we'd have a hump like a car's transmission tunnel if we had a standard prop shaft) and have a huge alternator with an equally huge leisure battery bank. Obviously that would usually require a bigger engine and likely reduce fuel economy, the energy having to come from somewhere after all. There's lots of discussion on the various hybrid threads about how you can have a smaller engine than a traditional set up. Surely you can do similar if you "remove" the alternator from the system when maximum engine power is needed to the prop? Drop it back in when cruising and use some of the diesel's "spare" energy production capacity. So the question is, could such a big alternator have some form of clutch or other mechanism to disengage it from the drive system? Is that what's hinted at above with a hydraulically driven alternator? If that's feasible it would suit our increased energy demands but mean we could use cheaper leisure batteries instead of traction batteries and of course we could look to add photo-voltaic to top up the battery bank when the sun's out.

I think that's at least part of the theory, yes, a bit like the totally incomprehensible KERS that Formula 1 cars use. I'm guessing that the diesel engine generates maybe 50% of max power when running so that some of the electricity generated is banked either for domestic use, or for propulsion the following day. I can see why boatbuilders don't offer this though, it's almost impossible to find one company who can put together a simple system that they can install.

I realise, having read the other posts on diesel-electric, that this could be opening a big fat can of worms, but I thought I'd ask anyway. There's been plenty of discussion on the merits of d/e and traditional shaft drive, but no one seems to have touched on the idea of using it as an alternative method of transmission than hydraulic. It strikes me that maybe better the cost/benefits are more balanced. Why am I interested? We're looking at a semi-Dutch barge/widebeam boat design. Like a Dutch barge it'll have a collapsible wheelhouse and rear cabin, like a wide-beam it'll be lower. Why do we want this? We're contrary, we like the look and we want the two decent size cabins and the two distinct living areas this will give us. The downside, of course, is transmitting the power from the engine under the wheelhouse floor, too the prop under the stern. Our builder has suggested hydraulic drive, but the more I read about it the more concerned I get, it sounds very complicated, what with cooling tanks and high pressures and extra anodes. It also sounds high-maintenance especially given that for much of the time we'll be sitting at our mooring, running shore power with occasional trips of a couple of hundred yards to the pump-out and back. Yes, wee want to get out and about, but with a teenage daughter that's going to be restricted to holidays and long weekends. So I was wondering about diesel/electric as an alternative. I'm not talking about solar recharging, nor hours and hours of silent running although that would be good. We're happy to cruise with an engine running most the time. BUT my wife is disabled and with that brings a greater desire for some home comforts, like a microwave, fridge-freezer etc as well as a greater demand to operate her disability equipment like her reclining bed, the onboard wheelchair lift and charging wheelchair all of which prefer a decent 240v AC supply. In this specific case, I think diesel/electric might be viable for the following reasons: A large battery bank gives plenty domestic power when we cruise and it can kept in condition from the mooring's shore supply when we don't. We won't find ourselves draining our batteries overnight from all the extra domestic equipment. Less day to day checking. Or rather, more automated checking, less dipstick waving, oily hand making. An electric motor doesn't mind not doing anything for most the time, hydraulic systems always seem gunge up. Maintenance could be little more than checking the brushes and hoovering out the spiders. Electricity doesn't leak and leave an oily puddle on the floor. If something goes wrong, an electrician should be easier to find than a hydraulic engineer. Components can be replaced without heavy engineering, wires can run in trunking and be pulled through, circuit boards and brushes can be put in the post. Hydraulic pipework will need access hatches and possible destruction of built in furniture and inevitably mess. Cost of installation could be comparable, it might even be cheaper than hydraulic. And if battery technology advances and solar panels continue to get cheaper, we might be able to add a little free energy even it's just to run the fridge. Who wants to talk me out of it?

I figured better to resurrect than start afresh as there's a lot of useful stuff here. There's a couple of added benefits we could add. There's the ability to run on battery only for "silent running", the fact we could put the gen-set anywhere we wanted and the possibility of putting the drive in an external pod so no chance of a leaky gland (although it could look a bit odd).

I'm intrigued by this, not necessarily to use solar panels but as an alternative to hydraulic drive. If you think about it a parallel hybrid with a decent battery bank could be a good alternative. Let's assume that we have an NB that needs 60hp to run at top speed and 10hp to run at normal cruising speed. For a diesel boat we'd need a 60hp engine but for a diesel/electric we could have a smaller engine, say 40hp, running at optimum economical speed, generating electricity which is then stored in our battery bank. When we need top speed we can draw on that stored energy, and of course if we have some left over we can run all our 240v appliances. We could of course always add solar panels for extra generating capacity, but that is purely top up not primary drive. There's probably an optimum motor size, engine size, battery size, solar panel size, etc. which I can't for the life of me work out. Maybe someone will come in and work it out?

To be honest the list of requirements caused by my wife's disability and the fact that we'd seen an almost right equipped boat and spoken to her owners did mean we ended up with a very short shortlist of builders, who have so far been great. And moorings? Having read endless horror stories of London's overcrowding I got on Google Earth and tracked my way along the Paddington Arm noting down collections of boats. Then it was off on the motorbike for a game of ask the owners, and we've turned up a perfect mooring. Now we just need a boat to float on it.

Hi, We thought we'd better introduce ourselves and have a good read round before we start asking all the traditional newbie questions so here goes. We're Alex and Stef, both in our forties and having a bit of a mid-life crisis, and Kez who's 16 going on 25 and Jazzie the dog and Biz-biz the cat. Both Stef and I have longed for a boat since we were teenagers, she did something about it and spent some time on boats in her 20's, I just dreamed. Suddenly we're in the position to fulfil those dreams so we're going for it, totally the wrong way but what the heck, the deposit's paid and the plans are being drawn up. She'll be a 66'x12' boat with a wheelhouse and an aft cabin (but not a Dutch barge) and a lift (did we mention Stef uses a wheelchair?). Have we spent time on boats recently? No. Did we spend weeks visiting different boat-builders? No. Do we want to stay in London? Yes, we've no choice (see teenager). Will we make mistakes? Almost certainly. So hello all.