Recent content by jonr

> I don't know if it would be a very profitable business, but maybe break even ... It depends what you use it to smuggle :-)

Here is a link that suggests it is hard to beat an outboard engine if you need something suitable for predictable shallow water. http://www.boatingmag.com/boats/boat-engine-comparison-outboard-vs-sterndrive-vs-jet-drive

Like a car without a differential, I think a wide propeller would slightly resist turning. But more critical would be if one propeller creates more velocity over the rudder (perhaps you excluded that).

A someone mentioned, an outboard drive powered by an inboard diesel and a hydraulic pump/motor may make sense for a boat that needs to run up on the beach. Careful attention to hydraulic pump/motor efficiency should mean that they are a net efficiency gain over gas engines. People run jet...

IMO, the best way to start designing a boat is to look at the existing ones that come closest to your specs. If you expect yours to go twice as fast with the same power, you have a problem.

I understand that outboard HP is measured at the prop and an inboard engine is measured before the gearbox. So at the prop shaft, an OB has the advantage. Energy per gallon doesn't matter if it's burned in an inefficient engine and you get less HP-hours per gallon.

I'm curious how much efficiency one gains from using a 16" 900 rpm prop over something like a 11" 1800 rpm on a high-thrust Yamaha T9.9. 10%? It would also be interesting to compare BSFC numbers. I suspect about the same (old diesel vs new 4 stroke gas).

Probably the LR2 here: http://www.bluemoment.com/manuals/lister_man.pdf

I think that lanolin or grease mixed with waste oil would stick better.

I agree, people seem to get quite good efficiency and total hours from Honda inverter generators. Eventually we will see more people using lithium batteries - they are a better match for quick and/or partial charges from a generator.

A full, sealed can of beer is pretty strong.

I've suggested this too. It works well for inflatables. Fiberglass and aluminum compartments could have a plastic bladder inside to make them airtight. And while load capacity would be reduced if a bladder leaked, the boat wouldn't sink.

I would have guessed that if you know the forces will be say downward, then the bottom should be strong in tension and the top strong in compression. Mixing fibers with different tensile moduli in the same layer/direction seems like a way to get the advantages of neither.

You can Google "wire arc spray" or "thermal spray". It's been done on fiberglass and metal boats. My understanding is that with fiberglass, they sprayed on epoxy with micro-ballons and then sanded it a little. This gave it some tooth to adhere well. It's not popular, so perhaps it wasn't...

But a metal arc spray machine and apply zinc/aluminum or perhaps some copper mix. It cools fast enough that it doesn't harm fiberglass.