Originally Posted by speedoo
I think making hull speed with "no problem" is a bit optimistic. I had no problem getting a 32 foot, 10,500 pounder to hull speed with a 13 hp older Volvo
, in relatively calm conditions, but with another 1500 pounds dry weight, I don't know. I do agree with your fuel economy comment.
And most would consider that size boat with that kind of engine
underpowered (for coastal cruising anyway), which means hard to sell when that time comes.
Is that "old standard" really adequate? If you have a knot
or two of adverse current, you are making no headway.
of thumb I know of is that 1hp/1000lb will get you to hull speed. A poor hull shape, bottom condition and overhangs will affect this a bit up or a lot down.
The 'old standard' is old, as I indicated, 1950's or 60's and earlier. The circumstances of society, changes in the costs of things and general feelings about risk and safety
have changed the standard.
In the 1950's, let's say, fuel was cheaper in the absolute sense, but not in the relative sense, adjusted for inflation fuel was $2 to 6.50/gal or more, depending on how inflation is reckoned.(http://www.measuringworth.com/calcul...mpare/2009.htm
As a percentage of what people earned fuel was more costly.
My understanding is that food
was too, which meant there was less disposable income
, as a percentage of income
, for fuel to begin with. Other things like housing I believe were cheaper. I don't have the energy to track down the info on food
and housing, I am just remembering things I read long ago.
I believe engines were more expensive too skewing preferences towards smaller engines.
In the 1950's there were fewer people cruising both in absolute numbers and as a percentage of the population. I believe the people that did so tended to be more skilled as the barriers to entry were higher weeding out many of those who weren't as committed to the sport.
Today boat companies have 2 incentives to have the standard be higher, increased profits from selling larger engines and decreased liability from 'design defect' law suits where somebody has a need to motor into a hurricane
at hull speed and can't.
Part of it too is that people think that faster motoring ability in adverse winds is safer.
To sum up, good marketing
, increased disposable income, the general American tendancy to think bigger is better and cheaper recent energy prices and perhaps hardware
prices have changed the standard.
Personally I like the old standard. I think the art of motor sailing is rather neglected these days, I consistently see people motoring in moderate air with no sails
up. Ok they need to make tracks to get back to work the next day, but they could motor sail at hull speed for the fuel consumption
of considerably less. In heavy air motor sailing is just about as fast but a lot more comfortable than motoring straight up wind. In most situations I can think of motor sailing with a smaller engine will be as effective as just motoring with a larger one.
There is a benefit of going with a smaller engine, for the same weight you can install a larger fuel tank
. In calm conditions motoring, you can go slower without taking the motor out of its comfort zone, this increases fuel economy and therefore range even more.
I inclined to think there are more situations that I would get into where increased range would be important than situations where more power and marginally more speed would be important.