Diesel Alternatives to High Thrust Outboards
- I don't like the high thrust outboards that seem to be the optimal propulsion for many Bolger designs.
Let me rephrase that, I actually have the highest respect for modern outboards like the Yamaha 4 stroke 9.9. It is a very respectable machine. It's the GASOLINE that I don't like. I've used diesel at sea my adult life, and I don't like gasoline on the boat.
On the hull forms of AS29, AS39: what are the options to replace a 9.9 HT outboard with a suitable diesel?
The best I can think of without redesigning the entire boat is a 10 HP diesel mounted to a Sonic outdrive leg. This would require some redesign of the stern, but not a wholesale redesign. (though might screw up weight distribution)
Sonic is also not a really good option financially.. I think the Sonic drives cost about 3K alone.
Switching gears in a related manner.. what are the engine specs in the Ataraxia design? Could that be adapted to replace a 9.9 HT in the AS29, AS39?
Thanks for reading..
I just noticed this thread and hasten to throw in the fact that I have a 1960s 4-stroke outboard to dispose of. It is a Bearcat 55, same thing as the slightly earlier Homelite 55, made by mounting an upended Crosley car engine on a beefed up Scott Atwater lower unit. I remember seeing one in Monkey Wards in its day. This was running on a 16 foot Lyman until 4 years ago. Fans of these motors claim there was a comparison test done with late Nineties Mercury 4-strokes of same power. Results were virtually identical on fuel economy, noise, rpm, performance. Owner of this one apparently loved it but had to tinker: I found a timing light and spare carburetor in the boat. It’s heavy.
Look forward to seeing them over here. The earlier BMW F-800 twin was aiming for high-efficiency while maintaining higher RPM-based power-curve.
Oddly enough, because that characteristic supports the 'relaxed' driving-style - not for 500-miles day though - some of the 'old-timey-flavor' American-Cruisers knock-offs such as HONDA's VT 1100 V-twin have had long-stroke torquey liquid-cooled engines for several decades, with around 2500rpm for peak torque on some sub-models. But mileage has always been middling with perhaps high 40s (US), which can be matched by a PRIUS or turbo-diesel VW POLO...
Susanne Altenburger, PB&F
----- Original Message -----
Sent: Saturday, September 15, 2012 7:45 AM
Subject: [bolger] Re: Diesel Alternatives to High Thrust Outboards
Honda are now setting a bike trend in this with their new mid-sized Integra bikes that borrow heavily from slow revving low friction car engine technology - and some other tricks. Torque curve is flat from around only 2000rpm. The parallel twin 700cc engines are essentially that of a Honda Jazz cut in half, and have fuel consumption comparable to much smaller bikes, claimed around 28km/L. They have invested quite a bit of time in developing the engine design aimed to give good performance/economy in the speed ranges bikes are actually ridden at ninety percent of the time by ninety percent of riders.
--- In email@example.com, <philbolger@...> wrote:
> HONDA's first INSIGHT - alu-body - was indeed powered by an under-square/long-stroke gasoline non-turbo engine, with the second engine-version dropping peak torque further from 2000 to 1500, with corresponding adjustments in the gearing, which gained another 10+% in its unprecedented mileage or some such...