On Sun, Feb 24, 2008 at 11:07 AM, Captain Beeky <[EMAIL PROTECTED]> wrote: > > On 24 Feb 2008, at 10:47, Michael Askin wrote: > > > Running a propeller when free running is much lighter work than when > > moored or towing > > I have a problem with this concept. How does the engine know what is > going on "out back" ? <snip> > I suppose when underway in forward gear the water being pushed > backwards by the prop already has some relative backward motion > relative to the prop . . . . > > Beeky >
You've answered your own question! :-) Saves me from having to do it, but I will anyway! You may notice that an engine accelerating a boat has to work harder. Also for the same power engine, a larger boat will require more revs to get it going the same speed. It's also a log relationship, i.e. to get a boat moving slowly is easy, the faster you go the more power you need exponentially. That's why going tickover produces much less loading than going faster. Now if someone can explain why pushing a tide seems to make the engine sound like its working harder? I still think it's a psychological thing, but my Dad thinks otherwise! Cheers, Mike -- Michael Askin http://shoestring_DOT_zapto_DOT_org/
